Resorbable polymer matrices: chitosan-substituted collagen-based biomaterials

CHAPTER

Resorbable polymer matrices: chitosansubstituted collagen-based biomaterials

9

Ganesan Krishnamoorthy1, Gopal Pugazhenthi2 and Danaboyina Ramaiah1 1

Natural Product Chemistry Groups, Chemical Science & Technology Division, CSIR-North East Institute of Science & Technology, Jorhat, India 2 Department of Chemical Engineering, Indian Institute of Technology, Guwahati, India

9.1 Introduction The advent of material manufacturing and processing technologies through multidisciplinary efforts has yielded novel biomaterials for applications in tissue engineering and drug delivery. The most commonly used biomaterials are derived from natural and modified natural polymers, synthetic polymers, and composites, and also are based on metals/ceramics (Maitz, 2015). Recently resorbable biomaterials have gained much attention because of their effectiveness in biomedical applications (Meinig, 2010; Kim and Jung, 2013). These are the most versatile and promising materials because they can be engineered to fulfill specific requirements such as mechanical strength and rate of biodegradation. Ideal biomaterials for implantations, for example, should have desirable properties like biocompatibility, biostability, bioresorbability, and mechanical strength, and they should be replaceable by mature extracellular matrix (ECM). Also, these materials must undergo degradation/dissolving of their ingredient molecules and be entirely reabsorbable by the host system. The most important advantage for using resorbable biomaterials is that no subsequent surgical intervention is required to remove them from the host after implantation. Such effective resorbable biomaterials play a major role as scaffolds in tissue engineering and regenerative medicine, and as drug delivery systems. The origins of these materials are diverse, including natural, synthetic, or semisynthetic polymers, as summarized in Table 9.1 (Bohner, 2010; Mogosanu and Grumezescu, 2014; Zhang et al., 2015a,b). Natural polymers include collagen, chitosan, alginate, fibrins, albumin, gluten, elastin, fibroin, hyaluronic acid, cellulose, starch, pectin (pectinic acid), dextran, pullulan, heparin, and silk, among others. Major interest in these natural polymers stems from their biocompatibility, relative abundance, commercial availability, and ease of processing. In general, natural polymers have good biocompatibility, Materials for Biomedical Engineering: Absorbable Polymers. DOI: https://doi.org/10.1016/B978-0-12-818415-8.00009-7 © 2019 Elsevier Inc. All rights reserved.

245

246

CHAPTER 9 Resorbable polymer matrices

Table 9.1 Resorbable polymers from natural and synthetic sources. Classifications

Sources Animal derived

Natural polymers

Plant derived

Microbial derived

Synthetic polymers

Semisynthetic polymers

Types of polymers Collagen Keratin Fibrin Albumin Glycosaminoglycans Elastin Gelatin Chitosan Dextran Silk fibroin Gluten Hyaluronic acid Cellulose Starch Pectin (pectinic acid) Pullulan Xanthan Alginate Bacterial cellulose Poly(γ-glutamic acid) Microbial hyaluronic acid Exopolysaccharides Polyhydroxyalkanoates Poly(hydroxy acids) Poly(glycolic acid) Poly(lactic acid) Poly(ε-caprolactone) polydioxanone Poly(ortho esters) Poly(trimethylene carbonate) Polyurethanes Polyanhydrides Poly(amino acids) Polyphosphazenes Cellulose nitrate Cellulose acetate Methyl cellulose Hydroxyethyl cellulose

9.1 Introduction

biodegradability, and bioresorbable, while synthetic polymers can be tailored to impart a wide range of predictable physicochemical, mechanical, and degradation properties (Bachinger et al., 2010; Grumezescu et al., 2012; Radulescu et al., 2016). The most commonly and clinically used synthetic resorbable polymers are poly(hydroxy acids), poly(glycolic acid), poly(lactic acid) (PLA), poly(ε-caprolactone), and polydioxanone. The synthetic resorbable polymers include poly(ortho esters), poly(trimethylene carbonate), polyurethanes, polyanhydrides, poly(amino acids), and polyphosphazenes, which are also being explored for use in biomedical fields (Nair and Laurencin, 2007; Valapa et al., 2014, 2016a,b). Among the natural biopolymers, collagens and chitosans (Fig. 9.1) are abundantly available (Hayashi et al., 2012). These biopolymers have been well exploited for the design of multifunctionalized biomaterials for tissue engineering and drug delivery, and also as temporary scaffolds with mechanical and biochemical support. Both the biopolymer-based biomaterials exhibit good biodegradability, biocompatibility, and bioresorbability, and weak antigenicity compared to other natural polymers. There were also many reports on fabrication of chitosansubstituted collagen-based biomaterials for tissue engineering and drug delivery applications (Purcel et al., 2016; Anitha et al., 2014; Radulescu et al., 2016; Mogosanu et al., 2016; Martı´nez et al., 2015). Both the biopolymers, collagens and chitosans, do not exist together as hybrids in nature, but the specific properties of each of these may be used to produce hybrids that confer unique structural and mechanical properties. These materials have shown that chitosan can modify the properties of collagen. The hybrids of collagen with chitosan have been intensively investigated for the design of polymeric biomaterials as a tissue implant and as for well-controlled

FIGURE 9.1 Molecular structures of collagen triple helix and chitosan.

247

248

CHAPTER 9 Resorbable polymer matrices

delivery of therapeutics. These materials have possessed active responsiveness to the environmental signals and may change some physicochemical properties on demand (Barroso et al., 2014; Martı´nez et al., 2015). The combination of collagen with chitosan could revolutionize the current state of the biomaterials in biomedical fields. This chapter gives a survey of chitosan-substituted collagen-based resorbable biomaterials for biomedical applications (Table 9.3). Furthermore it discusses the structure and biodegradability properties, challenges, and future perspectives including mechanical properties of these materials for applications in healing or tissue regeneration.

9.2 Collagen chitosan-based biomaterials The design of advanced multistructured biomaterials based on collagen chitosan is of tremendous interest in recent years, because of their applications in the biomedical fields. These biomaterials are more expensive due to a shortage of these polymers; in addition, they suffer from batch-to-batch variation and are vulnerable to the possibility of cross-contamination during isolation from plant and animal sources. On the contrary, the physicochemical properties and quality of the synthetic polymer-based biomaterials can be easily controlled without immunogenicity. To achieve the desired physical and mechanical properties of the tissueengineered biomaterials for various applications, their molecular structure and weight can be easily controlled during the process (Tangsadthakun et al., 2007; Chen et al., 2011; Hirano et al., 2000; Raftery et al., 2016; Martı´nez et al., 2015). Chitosan-substituted collagen-based biomaterials have been synthesized by numerous methods such as film casting, freeze-drying, and electrospinning using mild conditions as summarized in Table 9.2 (Arpornmaeklong et al., 2007; Wang et al., 2011a,b; Bai et al., 2013). These materials have also been fabricated along with naturally occurring biopolymers, synthetic polymers, and synthetic charged polymers (Sionkowska et al., 2016). The synthesis of the biomaterials in the form of films, sponge, capsules (micro/nano), and hollow capsules can also be achieved. These materials with various properties (e.g., biocompatibility, porosity, charges, mechanical strength, and hydrophobicity) can serve as tissue engineering material and for drug delivery. These properties can be easily altered by changing the constituents of monomers/polymers, by controlling assembly and blending conditions, or by introducing new functional groups: cation/anion exchanger, carboxylic/amino, cyano, groups and pH, hydrophobicity, hydrophilicity, H-bonding, and selective binding to the synthetic and natural polymers. Various research groups have reviewed the sustainability of the drugs from these biomaterials, such as thermodynamically multilayered stable particles (micro/nanoparticles) or injectable/implantable materials. The release of drugs from these materials is generally dissociation-controlled; however, the sustained release over a long time period may not be expected. It is critical to enhance the

9.2 Collagen chitosan-based biomaterials

Table 9.2 Collagen chitosan matrices for tissue engineering and drug delivery. S. no.

Matrix form

Application

Tissue engineering 1.

Membranous (films/sheets/disks)

2. 3. 4. 5. 6. 7.

Porous (sponge, felt, fibers) Gel (hydrogel/microgel/nanogel) Solution Filament Tubular (membrane, sponge) Composite Collagen chitosan/synthetic polymer Collagen chitosan/biological polymer Collagen/ceramic

Oral tissue repair, dura repair Cartilage repair, soft-tissue augmentation Soft and hard tissue augmentation Soft and hard tissue augmentation Tendon and ligament repair Nerve repair, vascular repair (blood vessels) Vascular repair, skin repair Soft tissue augmentation, skin repair Hard tissue repair (bone and dentin)

Drug delivery 1. 2. 3.

Membranous (films/sheets/disk) Porous (sponge, felt, and fibers) Gel

4. 5. 6.

Solution Tubular (membrane, sponge) Composite collagen chitosan/synthetic polymer collagen chitosan/biological polymer

Wound dressing, patches Wound dressing, drug and biological molecule delivery such as protein, gene carriers Drug carriers Depot drug carriers Wound dressing, depot drug carriers

sustainability of drug from these materials. The biodegradability of these materials is also an important factor for sustainability. These degradable biomaterials do not require surgical removal and, importantly, the release of the entrapped drugs can be regulated by the degradation behavior of these materials as well as by the simple diffusion techniques (Chen et al., 2008, 2015; Horn et al., 2009; Wang et al., 2016). The advantages of these biomaterials are the absence of hazardous substances and the use of simple procedure along with possibility to introduce high degree multifunctionality (Raftery et al., 2016). The mechanical strength (elasticity and rigidity), hydrothermal and biological stability, internal and hydration, and permeability properties of these materials are influenced by different parameters such as

249

250

CHAPTER 9 Resorbable polymer matrices

the physicochemical nature of these polymers and the interactions between collagen and chitosan. The sophisticated multiple functionalities in these systems can be simultaneously engineered by loading several types of molecules on the surface or within. The surface of these biomaterials can also be altered to partially control their functionality. Such modifications can protect drugs from proteolysis and antibody neutralization, resulting in a prolonged retention of the drug activity in vivo. These aspects have been recently described as suitable approaches for theranostics, because elements for diagnostics can be encapsulated in some subcompartments and the drugs for therapy can be encapsulated in other subcompartments in multicompartmental biomaterials. This is not only appropriate for these materials but almost any type of charged species. These include inorganic and organic molecular clusters, micro/nanoparticles, nanofibers, nanotubes, nanowires, nanoplates, dendrimers, porphyrins, polysaccharides, nucleic acids (DNA and RNA), polypeptides, proteins, and viruses (Wang et al., 2011a,b; Wan et al., 2013; Raftery et al., 2015). Furthermore, these biomaterials have been investigated to functionalize their surface for the sustained delivery of genes, growth factors, and cytokines. Such effective systems may offer the potential to concentrate the therapeutics and deliver them locally, as opposed to topical administration (Lee et al., 2004, 2006; Liu et al., 2013; Cao et al., 2012), and are also useful for the local delivery of growth factors and stem cells for tissue engineering constructs and regenerative medicines (Chiu and Radisic, 2011). These materials have acquired enormous interest in the field to render implantable material surfaces more functionalized biomimetics (Raftery et al., 2015) and to modulate protein adsorption, promote cell adhesion, and regulate the inflammatory responses (Mahmoud and Salama, 2016). In addition, these biomaterial coatings have the potential to mimic the ECM complex in vivo (Raftery et al., 2016). Studies have also been conducted to tailor the collagen chitosan biomaterial surface topography, chemical composition, mechanical properties, and degradation to recapitulate the in vivo ECM environment. Subsequently, the physicochemical and mechanical properties of these materials have been altered to impact cell and tissue adhesion, maintaining and, more importantly, directing cellular phenotypes.

9.2.1 Types of resorbable polymers Resorbable polymers can be classified on the basis of their origin, such as natural and synthetic sources (Nair and Laurencin, 2007; Kim and Jung, 2013; Mogosanu and Grumezescu, 2014; Zhang et al., 2015a,b). These polymers can be naturally broken down over time and can be eliminated from the body. The resorption of these degraded polymers can be mediated by water, enzymes, or microorganisms. In general, natural polymers are usually degraded by enzymatic degradation, while synthetic polymers are usually broken down by ester hydrolysis.

9.2 Collagen chitosan-based biomaterials

9.2.1.1 Natural resorbable polymers Natural polymers can be classified on the basis of their origin as (1) protein-based systems and (2) polysaccharide-based systems. The protein-based polymers are, namely, collagen, gelatin, silk fibroin, fibrin, and elastin. Among these, collagen obtained from animal sources has been extensively exploited to develop products for commercial applications such as tissue engineering. Polysaccharide-based polymers (e.g., chitosan, starch, alginate, hyaluronate (HA), and dextran) show interesting properties such as good hemocompatibility, good interactions with cells, nontoxicity, and lower cost with respect to other biopolymers such as collagen, thereby justifying their use as scaffold materials in tissue engineering applications (Mogosanu et al., 2016). Collagen. Collagens are coiled-coil fibrous proteins that contain both acid and basic amino acid residues and bear either a positive or negative charge depending on the pH of the medium (Purcel et al., 2016). The main applications of collagenbased biomaterials are as drug delivery systems including shields in ophthalmology, sponges for burns and wounds, mini pellets and tablets for protein delivery, and to promote cell and tissue growth. These proteins are one of the most important biopolymers and the main fibrous protein of ECM of connective tissue in multicellular animals. Collagen is the most abundant protein in mammals and probably the most abundant animal protein in nature. These proteins account for c.30% of the total human body proteins. Collagens are located in the connective tissues, and tough bundles of collagen, called fibers, are the major component of the ECM that supports most tissues (Buehler, 2006). The schematic representation of the formation of nanoscale bundles from the self-assembled collagen triple helices at physiological pH are shown in Fig. 9.2. These proteins possess great tensile strength and are the main component of cartilage, ligaments, tendons, bone, and teeth. The extraction and purification of collagen from animal source is shown in Fig. 9.3. Furthermore, cross-linking with various agents such as polyphenolics, 1-ethyl-3-(3-dimethylamino-propyl)-carbodiimide/N-hydroxysuccinimide (EDC/NHS), and D-amino acids (Ashwin and McDonnell, 2010; Madhan et al., 2007; Krishnamoorthy et al., 2008, 2011, 2012, 2013a,b,c, 2014) has been investigated to improve the stability and biological applications of collagen (Fig. 9.4). Chitosan. In the past few years, chitosan, a cationic polymer of (1 4)-β-linked D-glucosamine (GlcN) and N-acetyl-D-glucosamine (GlcNAc), has received considerable attention in biomedical applications (Jiang et al., 2014; Anitha et al., 2014). Owing to its high charge density, it adheres to the negatively charged surfaces, and chelates with metal ions. It is also used in therapeutic delivery for translation medicine because of its good biocompatibility, antimicrobial, biodegradability, and bioresorbability (Grumezescu et al., 2012, 2013). Various chitosan-based biomaterials could revolutionize the current state of the therapeutic strategies, while the cellular chitosan biomaterials are applied surgically to the targeted site. Chitosan shows potential pro-inflammatory properties through the

251

252

CHAPTER 9 Resorbable polymer matrices

FIGURE 9.2 Schematic representation of formation of the nanoscale bundles from the self-assembled collagen triple helices under physiological conditions.

release of chemical mediators. These materials stimulate the migration of the polymorphonuclear leukocytes and macrophages and promote angiogenesis, reorganization of the ECM and granulation of tissue formation. Chitosan has been used in tissue engineering, with a wide variety of applications ranging from skin, bone, cartilage, and vascular grafts.

9.2.1.2 Synthetic resorbable polymers One of the major classes of synthetic bioresorbable polymers are aliphatic polyesters or poly(α-hydroxy acids). Poly(α-hydroxy acids) such as polyglutamic acid (PGA), PLA, stereoisomers poly(L-lactic acid) and poly(D-lactic acid), and poly (lactic-co-glycolic acid) (PLGA) copolymers are the most widely used resorbable polymers, as they have been approved by Food and Drug Administration for clinical use in humans in different forms (e.g., fibers for sutures and injectable forms). These polymers are commonly used in regenerative medicine applications (Kakati et al., 2012; Sahu and Pugazhenthi, 2012; Valapa et al., 2014, 2016a,b; Chakraborty et al., 2016; Mogo¸sanu et al., 2016; Suresh et al., 2016).

9.2 Collagen chitosan-based biomaterials

FIGURE 9.3 Schematic representation of isolation of collagen from animal sources.

9.2.2 Supramolecular collagen chitosan complexes The resorbable collagen and chitosan matrices may create an appropriate environment for the regeneration of ECM, and both of these materials are hemostatic. Besides that, however, the mechanical properties and biodegradation rates of the two natural materials, especially in aqueous media, are not particularly good.

253

254

CHAPTER 9 Resorbable polymer matrices

FIGURE 9.4 Schematic representation of (A) cross-linking bridge between collagen and D-amino acids and (B) self-assembly and staggered alignment of collagen fibrils at pH 7 (Krishnamoorthy et al., 2013a,b,c).

A common approach adopted for changing the properties of these materials is by cross-linking with various agents. Both physical and chemical approaches have been adopted for cross-linking, such as thermal heating, ultraviolet (UV) irradiation, and treatment with glutaraldehyde or polyepoxy compounds. This was carried out by using cross-linking agent EDC in NHS and a 2-morpholinoethane sulfonic acid buffer system. In addition, this matrix provided many more amino groups than required for cross-linking, which led to a decrease of the relative cross-linking degree and the mechanical strength of the biopolymer (Ye et al., 2007; Chen et al., 2008; Wang et al., 2005, 2013). The molecular structure of the complex formed between collagen, chitosan, and chitosan dialdehyde is shown in Fig. 9.5.

9.2.3 Advantages of resorbable collagen chitosan polymers The polymers based on collagen and chitosan have the potential to replace existing materials used in medical devices. These resorbable polymers are inexpensive

9.3 Fabrication of 2D and 3D collagen chitosan biomaterials

FIGURE 9.5 Structure of the complex formed between collagen and chitosan and chitosan dialdehyde.

and can be tailored to degrade over a wide range of conditions to them suitable for many applications. These polymers are degraded by either hydrolysis or enzymes with their by-products being metabolized naturally. Therefore the subsequent surgical procedure is not required to remove the implanted materials. It is expected that the natural metabolism allows for tissue regrowth to replace the implant. If additional surgery is needed, it can be carried without complications. Moreover, such materials have the potential for sustained delivery of bioactives and are well proven in the biomedical sector with a wide range of benefits (Fernandes et al., 2011).

9.3 Fabrication of 2D and 3D collagen chitosan biomaterials As mentioned, a great feature of collagen chitosan biomaterials is that they can be fabricated into a number of forms. This section highlights many of these and how they are produced. Membranous matrix (films/sheets/disks). Membranous materials such as films, sheets, and disks can be produced by various methods such as film casting, airdrying, and freeze-drying, and using the collagen solution along with chitosan on nonadhesive surface as summarized in Table 9.2 (Silva et al., 2001; Sionkowska, 2006; Chirita, 2008; Uriarte-Montoya et al., 2010; Ahmad et al., 2016). The thermal, mechanical, and biodegradation properties of these films have been investigated by various research groups (Wang et al., 2003; Sionkowska et al., 2006; Chirita, 2008). These have the potential to be used in tissue engineering, including regeneration of peripheral nerves (Meyer et al., 2016), cardiovascular prostheses (Lima et al., 2006), cell/tissue adhesion (Wang et al., 2015), localized

255

256

CHAPTER 9 Resorbable polymer matrices

delivery of hydrophobic antitumor drugs (Chen et al., 2015), and wound healing materials (Ramasamy and Shanmugam, 2015). The preparation of chitosan collagen films and mechanism of the chitosan collagen-based cell-targeting drug carrier have been well studied in the literature (Wang et al., 2015). Porous matrix (sponges/felts/fibers). The porous materials such as sponge, felt, and fibers are generally obtained by freeze-drying an aqueous volume of collagen along with chitosan solution/dispersion. These materials have the potential for tissue engineering (Lin et al., 2009), dermal tissue engineering (Ding et al., 2008; Ma et al., 2014), wound healing, bone regeneration (Jung et al., 2007; Arpornmaeklong et al., 2007, 2008), and drug delivery applications. Chitosan improved the biostability of the collagen sponges and exhibited noncytotoxicity, biocompatibility, and nonhemolysis. These sponges showed a higher resistance to enzymatic degradation than the collagen-based sponges (Arpornmaeklong et al., 2008) and showed great promise as scaffolding material for tissue engineering purposes. In addition, the sponges promote the growth and differentiation of osteoblasts into the mature stage. Gel matrix (micro/nanogels). Gels such as microgel and nanogel can be formed by self-assembly and microfabrication using collagen along with chitosan solution (Ahmadi et al., 2013; Horn et al., 2015; Song et al., 2016; Deepthi et al., 2016; Li et al., 2019). These materials have attractive properties and are found to be excellent materials for tissue engineering (Moreira et al., 2016; Song et al., 2017) and drug delivery. These systems are highly advantageous for studying the effect of intercellular distance on cell cell interactions and provide a robust tool to explore the impact of both cell cell contact aspects (Song et al., 2016). The materials have potential applications in wound healing (Mahmoud and Salama, 2016), corneal surgery (Rafat et al., 2008), bone regeneration (Huang et al., 2011a,b; Wang et al., 2011a,b), cell culture (Rao et al., 2012), cardiac drug delivery (Chiu and Radisic, 2011; Reis et al., 2012), and spine fusion (Karaca and Patir, 2016). Particulate matrix (micro/nanoparticles). The particulate matrices, including micro- and nanoparticles, can be generated using collagen along with a chitosan solution (Chen et al., 2015; Anandhakumar et al., 2017; Karri et al., 2016). They have found applications in diabetic wound healing and as smart drug delivery systems. A biodegradable asymmetric chitosan membrane containing collagen nanospheres for skin tissue substitute (Chen et al., 2009) and enhanced loading and controlled release of rhBMP-2 in thin mineralized collagen coatings with the chitosan nanospheres and its biological evaluations (Kong et al., 2014) have been demonstrated. Filamentous matrix. An extrusion method is generally used to produce filamentous matrices, which can be applied in tissue regeneration and drug delivery. Novel self-assembly-induced 3D plotting for macro/nanoporous collagen scaffolds comprised of nanofibrous collagen filaments has been prepared that possessed reasonable mechanical properties and excellent biocompatibility and allowed nerve outgrowth (Wlaszczuk et al., 2016).

9.4 Design of resorbable collagen chitosan-based implants

Tubular matrix (sponge/membranous). Tubular matrices such as sponge and membranous can also be formed by the extrusion method. Different properties of the tubular membranes can be obtained by controlling the drying properties. Numerous research reports suggest that these materials can be used in tissue engineering, wound healing (Ding et al., 2008), and nerve regeneration (Wlaszczuk et al., 2016). In addition, they have a profound application potential in blood vessel repair (Albanna et al., 2012) and nerve regeneration (Huang et al., 2011a,b), and for addition applications in tissue engineering of urothelium (Feng and Chiang, 2015). Composite matrix. Composite matrix can be fabricated using different mass ratios of collagen along with chitosan that were mixed and frozen into a film and sheet. These can be used as cell matrix for smooth muscle cells, fibroblasts, and bone marrow stromal cells (Fu et al., 2017). These biodegradable composite materials have been utilized to fabricate tissue-engineered heart valves (Fu et al., 2017), vascular grafts (Wu et al., 2015), wound dressings, and bone substitutes (Chen et al., 2006). The chitosan microspheres were prepared and combined with absorbable collagen sponges to maintain the controlled release of recombinant human bone morphogenetic protein-2 (rhBMP-2) for the treatment of segmental bone defects (Hou et al., 2012). Scaffolds based on collagen, chitosan, and nanostructured phosphates (Tomoaia et al., 2013) and enhanced biomineralization in osteoblasts on a novel electrospun biocomposite nanofibrous substrate of hydroxyapatite/collagen/chitosan (Zhang et al., 2010; Munhoz et al., 2018) for potential applications in bone tissue engineering have also been reported.

9.4 Design of resorbable collagen chitosan-based implants Design of resorbable implants for tissue or organ requires a thorough understanding of the structures and functions of the tissue and organ to be repaired. The structure and properties of these biomaterials need to be evaluated for repair and the design requirements. Nonweight-bearing tissues and organs are generally replaced with these biomaterials fabricated either from natural or synthetic materials. For example, implants for blood vessels, heart valves, and most soft-tissue repair fall into this class. The resorption can reach from biodegradation or environmentally induced degradation of implants from mechanical, thermal, and metal-catalyzed oxidation behaviors and permeation of body fluids into the implants. Biodegradation is particularly manifested in applications where there is repetitive stress or strain on the implant such as artificial blood vessels and heart valves (Sionkowska et al., 2016). In this context, novel mesoporous hydroxyapatite/chitosan composite for bone repair as a new kind of bone grafting materials (Zhang et al., 2012) showed excellent properties like adhesion, proliferation, and differentiation of osteoblast cells.

257

258

CHAPTER 9 Resorbable polymer matrices

9.5 Application of resorbable collagen chitosan biomaterials In this section, various applications of resorbable collagen chitosan biomaterials are discussed. Drug delivery. The resorbable biomaterials in the form of films (thin and thick multilayers), sponges, filaments, spheres, and capsules are most promising for drug delivery applications (Table 9.3). These consist of a nanometer scale complex system in drug encapsulation and sustainability in order to improve drug efficacy and bioavailability as well as to minimize toxicity effects. Primary goals for groups researching these biomaterials in drug delivery include (1) more specific drug targeting and delivery, (2) reduction in drug and adjuvant toxicity, while maintaining therapeutic effects, and (3) greater safety and biocompatibility.

Table 9.3 Survey of research and development on collagen chitosan matrices. S. no.

Application

Comments

1.

Hemostasis

2.

Dermatology

3.

Cardiovascular surgery and cardiology

4.

Neurosurgery

5.

Periodontal and oral surgery

6.

Ophthalmology

7.

Orthopedic surgery

8.

Other applications

Sponge and felt form in cardiovascular, neurosurgical, dermatological, orthopedic, oral surgical applications Injectable collagen for soft-tissue augmentation, collagen-based artificial skins, collagen-based wound dressing Collagen-coated and gelatin-coated vascular grafts, chemically produced human vein graft, bovine arterial grafts, porcine heart valves, bovine pericardial heart valves, vascular puncture hole seal device Guiding peripheral nerve regeneration, dura replacement material Collagen membranes for periodontal ligament regeneration, resorbable oral tissue wound dressings, collagen/hydroxyapatite for augmentation of alveolar ridge Collagen corneal shield to facilitate epithelial healing Collagen shield for drug delivery to eye Collagen with hydroxyapatite and autogenous bone marrow for bone repairCollagen matrix for meniscus regeneration; collagen material for replacement and regeneration of Achilles tendon, reconstituted collagen template Drug delivery support, delivery vehicles for growth factors and bioactive macromolecules, collagenous, matrix for delivery of cells for tissue and organ regeneration

9.5 Application of resorbable collagen chitosan biomaterials

Various research groups reported the encapsulation and sustainability of therapeutics from these biomaterials (Barroso et al., 2014; Zhang et al., 2015a,b; Chen et al., 2015; Anandhakumar et al., 2017). The release of therapeutics from the resorbable biomaterials is generally dissociation-controlled. The sustained release over a long period may not be expected. It is critical to enhance sustainability of therapeutics from these biomaterials, and biodegradability of biomaterials is also an important factor. A thorough investigation about drug encapsulation and release is needed in order to maximize drug loading into these biomaterials as well as biocompatibility information. Tissue engineering. The resorbable biomaterials, chitosan-substituted collagen, have gained immense interest in the biomedical field to render implantable material surfaces due to their tunable properties (Table 9.3). These materials have a significant impact in nearly every aspect of biomaterial design and tissue engineering. They have been employed to (1) modulate protein adsorption, (2) promote cell and tissue adhesion, (3) regulate the inflammatory response, and (4) mimic the complex of ECM. The studies have also been conducted to tailor these biomaterials’ surface topography, chemical composition, mechanical properties, and the degradation to recapitulate the in vivo ECM environment (Pon-On et al., 2014; Wang et al., 2015; Raftery et al., 2016). The effects of chemical and mechanical properties of these biomaterials and their impact on cell and tissue adhesion, more importantly, directing cellular phenotype, have also been discussed. Regenerative medicines. These biomaterials are being developed for a variety of biomedical applications (Table 9.3). One of these includes the cell contacting application in the regenerative medicines, owing to its easiness of arrangement and the opportunity to tailor not only their chemical and mechanical properties but also their biofunctional ones. In the field of regenerative medicine, the ability to sequester stem cells, growth factors, and chemokines to these biomaterials has been exploited to direct the lineage of progenitor cells and to subsequently maintain a desired phenotype. Recently, PLGA/polyethylene glycol microspheres containing vascular endothelial growth factor impregnated collagen chitosan scaffolds seeded with human adipose-derived stem cells have also been developed (Zhang et al., 2015a,b). The engineered adipose tissue with a vascular pedicle could conceivably be transferred as a vascularized soft-tissue pedicle flap or free flap to a recipient site for the repair of soft-tissue defects. The sustained release of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) from heparinized collagen/chitosan scaffolds to promote the angiogenesis (Sun et al., 2012) has also attracted much attention and which include (1) biocompatibility and bioinertness, (2) ability to incorporate biological molecules, such as proteins, (3) the high degree of molecular control of the structure and thickness, and (4) providing a much simpler approach to construct complex 3D surfaces. These materials can act as a reservoir, and their properties such as permeability, thickness, and charge density can be easily changed and easily coated on implants.

259

260

CHAPTER 9 Resorbable polymer matrices

9.6 Ideal properties of biosorbable biomaterials In this section, properties of biomaterials that would make them optimal for use in biomedicine are discussed. Mechanical properties. The best resorbable biomaterials seeded with cells should exhibit appropriate mechanical responses similar to the natural tissues. They temporarily deform upon mechanical stress with little structural collapse. The engineered biomaterials require a mechanic active that can transmit mechanical signals to its adherent cells in a physiologically dynamic environment. The resorbable polymers are able to effectively deliver the mechanical signals associated with the surrounding biological environment. These properties may enhance and facilitate the tissue regeneration process. The addition of chitosan to collagen scaffolds improved the mechanical properties, compressive strength, and swelling ratio, and prolonged the degradation rate (Raftery et al., 2016). Another work, reported by Pon-On et al. (2014), demonstrated significantly enhanced mechanical, mineral deposition, and biological properties of these composites, along with controlled release. The collagen/PLA, chitosan/PLA, and collagen/chitosan/PLA hybrid scaffolds were fabricated by the freeze-drying method for cartilage tissue engineering (Haaparanta et al., 2014) and have attracted attention to overcome the associated drawbacks. Biodegradability. Resorbable biomaterials are composed of an absorbable unit linked with degradable chains. In biomaterial degradation, monomers and lowmolecular-weight species are formed by the degradation process and these compounds are absorbed by the metabolic pathways. Since the degradation processes are mediated by water or enzymes, they can be distinguished as hydrolytic or enzymatic degradation respectively. Most synthetic polymer biomaterials are degraded by hydrolytic degradation, while the natural polymers are degraded by enzymatic degradation. Hydrolytic degradation depends on the water level, which is constant in a living body, while enzymatic degradation depends on the enzyme levels, which may vary widely not only from patient to patient but also between different tissues in the same patient. Thus the degradation of synthetic polymers based biomaterials tends to be more predictable than that of natural polymerbased biomaterials. The main factors that determine the hydrolytic degradation process are the chemical structure of the degradable chain in the polymer backbone, hydrophilic/hydrophobic character, polymer morphology, molecular weight, surface area, catalysts, and additives of resorbable polymers. Moreover, the chemical structure of the degradable chain in the polymer backbone is the most important parameter. From these properties, it is possible to predict degradation of a given polymer. The hydrophilic/hydrophobic character is another important parameter in polymer degradation. The degradation rate is further influenced by the polymer morphology. Semicrystalline polymers are composed of crystalline and amorphous regions, and in general the degradation tends to occur in the amorphous regions. This phenomenon can be easily observed in

9.7 Strategies to modify the properties of biomaterials

an absorbable monofilament suture with a high degree of crystallinity. With the poor stability of the chitosan-substituted collagen, it cannot match the demand of in vitro and in vivo applications in many cases due to fast biodegradation rate (Martı´nez et al., 2015). It is well known that bacterial collagenase specifically cleaves the peptide bond on the amino side of glycine in collagen sequences, while hydrolyses metabolize the chitosan molecules, leading to the release of amino sugars.

9.7 Strategies to modify the properties of biomaterials This section discusses varies strategies that have been employed to modify properties of biomaterials. Control of mechanical strength. The mechanical properties of the biomaterials are of immense importance for their various applications such as surface coatings and drug release. The effect of mechanical properties and their impact on cell and tissue adhesion are more important for directing the cellular phenotype. The optimization of mechanical properties has become a challenge. It is important to ensure that (1) they will be stable in different physiological conditions and (2) they can sustain different stresses (like shear stress). Since the biomaterials, chitosan collagen, can be derived from a variety of biosources, these materials are expected to have different mechanical properties (Pon-On et al., 2014; Raftery et al., 2016; Deepthi et al., 2016). Control of biodegradation rate. A variety of tissue engineering materials are being utilized in various biomedical devices, and it is very critical for the physicians to understand the properties of each biomaterial and to determine the suitability of these products for specific applications. Market surveys indicate that the concept of biodegradable soft or hard tissue implants has been introduced in the clinics, but more than 40% of the biomedical devices applied today are still nondegradable. One reason for this unwillingness is the insecurity regarding the predictability of the biodegradation time interval, especially when mechanical properties like tensile strength and elasticity are at the level demanded by the specific application. These problems can be overcome through the enhanced cross-linking, surface modification, copolymerization, and nanoparticles encapsulation, thus tailoring the biomaterial to meet the tissue-specific requirements (Pon-On et al., 2014; Martı´nez et al., 2015; Raftery et al., 2016; Deepthi et al., 2016), and much attention has been paid to overcome the limitations and to prolong stability of these biomaterials in the host after implantation. To devise the biomaterials and advanced biomaterials for biomedical devices, it is necessary to understand their in vitro and in vivo enzymatic biodegradation rates. Therefore tissue engineering approaches rely on the need to present the correct signals to cells in order to guide them to maintain tissue-specific functions. Various factors such as cell

261

262

CHAPTER 9 Resorbable polymer matrices

adhesion and diffusion on biomaterials, adsorption of hydrolytic enzymes on the biomaterials, may induce the enzymatic degradation rates. The studies detailed in the following section and kinetics analysis may evaluate the enzymatic degradation rate and could evaluate the stability. The dynamics analysis of enzymatic degradation could provide the insight into the exponential decay of the biomaterials and the actual mechanism involved.

9.8 Selection of cross-linking agents Biomaterials based on chitosan-substituted collagen cannot match the demand of in vitro and in vivo applications in many cases due to their poor mechanical strength, thermal instability, and fast biodegradation rate (Martı´nez et al., 2015). These aspects have been one of the crucial factors that limit the further use of these biomaterials. In this context, various approaches such as cross-linking and molecular interactions have been proposed as effective ways to delay the biodegradation rate and to optimize their mechanical strength and thermal stabilities. Presently there are three kinds of cross-linking methods frequently employed for improving the stability: physical, chemical, and enzymatic methods for such materials. Physical cross-linking. Various physical methods are used for cross-linking such as photooxidation, including dry heat, exposure to UV, or γ-irradiation, which could avoid introducing potential cytotoxic chemical residuals and sustain the biocompatibility of collagen chitosan matrix (Ma et al., 2003; Sionkowska et al., 2004, 2006; Chen et al., 2016; Raftery et al., 2016). Both dehydrothermal treatment and exposure to UV light increase the denaturation temperature, the resistance to proteolytic degradation, and the durability under load in protease. However, these biomaterials become partially denatured by these physical treatments. To keep degradation of the triple helices to a minimum, it is crucial for dehydrothermal treatment to reduce the water content via vacuum as thoroughly as possible prior to heating. Even small amounts of residual moisture can cause breakdown of the helical structures and proteolysis. Severe dehydration itself already induces amide formation and esterification among COOH, NH2, and OH groups. Nevertheless, the effect is insignificant and typical dry heating conditions are 110 C for several hours up to a few days. The combination of degradation and cross-linking allows nonspecific enzymes to attack and solubilize fragments of the cross-linked collagen biomaterial. Formation of cross-links during UV-irradiation is thought to be initiated by free radicals formed on aromatic amino acid residues, which indicate a rather limited maximum degree of cross-linking due to the small number of tyrosine and phenylalanine residues in collagen. Exposure times can therefore be kept short since cross-linking density soon reaches its limits, thereby affecting their use.

9.9 Stimuli-responsive resorbable biomaterials

Chemical cross-linking. Several recognized chemical cross-linking methods have been used for these biomaterials (Wang et al., 2003, 2011a,b; Ma et al., 2003; Sionkowska et al., 2014; Zhang et al., 2015a,b; Kishen et al., 2016; Yan et al., 2010; Liu et al., 2012; Gallyamov et al., 2014; Sionkowska et al., 2014). In chemical treatment, inorganic and organic agents are the most convenient and traditional agents. The use of bifunctional reagents to bridge free amine groups of Lys or Hyl residues on different polypeptide chains has been used for several years. Also, aldehyde cross-linking is the most extensively studied and is frequently applied method for the stabilization of these materials. This crosslinking can also suppress the immunogenicity of the artificial implant. However, accompanying the increase in stability of the matrix, other problems arise, such as over cross-linking and potential cytotoxicity. Therefore several alternative cross-linking agents such as acyl azides and EDC/NHS have been reported (Ma et al., 2003). Among these, the EDC/NHS cross-linking system is frequently used in the treatment of collagen chitosan matrix, which has shown better biocompatibility than glutaraldehyde. The cross-linking takes place by the reaction between COOH groups of glutamic/aspartic acid residues and amine groups of Lys/Arg of collagen to form amide bonds. Biocatalytic cross-linking. Collagen chitosan-based biomaterials were prepared with microbial transglutaminases biocatalyst, which showed high efficiency, selectivity, mild reaction conditions, and environmental friendliness (Fan et al., 2014a,b; Hu et al., 2019). It catalyzes the formation of covalent linkages between γ-carboxyamide groups of peptide-bound glutamine residues and E-amino groups of lysine or primary amino groups of a chitosan. This presents better moisture absorption, moisture retention abilities, and antioxidant activity, and was found to promote cell proliferation effectively. This type of method has been used for the protein cross-linking in the food industry (Sang et al., 2010). Collagen chitosan polymer conjugates. The N-isopropyl acrylamide grafted and collagen/chitosan-immobilized polypropylene nonwoven fabrics have shown excellent antibacterial and swelling properties (Wang et al., 2011a,b, 2012) and were found to be suitable for the healing of wounded skin area. The collagen/chitosan/poly(L-lactic acid-co-ε-caprolactone) were fabricated by electrospinning to form a vascular graft with excellent mechanical and biological properties (Yin et al., 2013). The layered collagen/chitosan-polycaprolactone scaffolds are found to be partially similar to the articular cartilage ECM in composition, porous microarchitecture, water content, and compressive mechanical properties, suggesting that they have promising potential for applications in articular cartilage repair (Zhu et al., 2014).

9.9 Stimuli-responsive resorbable biomaterials The properties of stimuli-responsive protein-based biomaterials are attracting much attention and have been investigated for biomedical applications

263

264

CHAPTER 9 Resorbable polymer matrices

Table 9.4 Stimuli-responsive collagen chitosan matrices reported in the literature. S. no.

Stimuliresponsive

1.

pH

2.

Temperature

3.

Photo/light

4.

Ultrasound

Matrices form

Applications

pH/temperature-responsive scaffolds pH/temperature-responsive scaffolds Photo/light-responsive scaffolds

Tissue engineering and release of bioactive molecules Tissue engineering and release of bioactive molecules Release of bioactive molecules Regenerative medicines Tissue engineering Bone implants

Ultrasound-responsive injectable scaffolds

(Caldorera-Moore and Peppas, 2009; Cross et al., 2016). The main focus is based on smart polymeric biomaterials with respect to possible applications in tissue regeneration and drug delivery, and the external stimulus used has been temperature/pH- and photoresponsiveness (Table 9.4). Smart biomaterials may also respond to more than one special stimulus. Some biomaterials are capable of responding to two or more different stimuli, sometimes even simultaneously. Stimuli like pH, temperature, salt, light-responsive, magnetic field, redox, and biodegradation, among others, have been exploited to induce the release the material of demand from these biomaterials (Jin et al., 2011; Higuchi et al., 2014). Temperature-responsive materials. Temperature is one of the most commonly used stimuli in smart biomaterials, since temperature changes are relatively easy to realize and to control both in vitro and in vivo conditions. Considering a smart biomaterial or a swollen smart biomaterial gel, this transition point is called critical temperature or temperature of volume phase transition. The pH/temperatureresponsive chitosan collagen scaffolds for tissue engineering and release of bioactive molecules have been reported (Barroso et al., 2014; Moreira et al., 2016; Song et al., 2017), which showed controllable biodegradation rate. pH-responsive materials. Structure and solubility changes in response to pH variations are common features of the biomaterials. The conformation of peptides, for instance, mainly depends on intra- and intermolecular interactions (H-bridge bonds, charge attractions). The protonation/deprotonation processes lead to conformational changes accompanied by alteration of the reactivity. Synthetic pH-responsive biomaterials bear ionizable functional groups, capable of accepting and donating protons according to the hydronium ion concentration in the solution. Ultrasound-responsive materials. The biomaterials become ultrasoundresponsive only when they attain the ability to heat up in the presence of ultrasound field [radio frequency (RF)]. The basic principle behind RF heating is Joule heating or magnetic heating. Even though there is no optimum RF

9.10 Photoresponsive resorbable biomaterials

conditions for effective heating, most of the reported research works have different RF exposures in their experiments. It has a range of 40 800 W. The ultrasound-responsive injectable chitosan/nano-hydroxyapatite/collagen scaffold for bone scaffolds were prepared (Chen et al., 2012). This ultrasound method is a good tool to evaluate the in vivo formation of injectable bone scaffolds and which facilitates the broad use to monitor tissue development and remodeling in bone tissue engineering. Photoresponsive materials. Photoresponsive biomaterials undergo a change in their properties in response to a light stimulus for controlled drug delivery. Photoaging and photodegradation properties of the collagen chitosan scaffolds were studied by solar and γ-ray irradiation (Sionkowska et al., 2004; Sionkowska, 2006; Chen et al., 2016). It was reported that the γ-ray irradiation can more significantly reduce the biostability of such materials.

9.10 Photoresponsive resorbable biomaterials As mentioned, photoresponsive resorbable biomaterials show great promise in biomedical applications. Following is a breakdown of studies in this area. Photophysical and photochemical properties. As expected, photoresponsive biomaterials endure a change in their properties in response to a light stimulus (Cui and Del Campo, 2014; Pereira and Bartolo, 2015). Different molecular properties can be regulated by the light, including conformation, polarity, charge, optical chirality, conjugation, etc. The light-induced change is reflected in a macroscopic change of material properties like shape, wettability, solubility, optical properties, conductivity, adhesion, and so on. Light control possesses intrinsic advantages compared to temperature, pH, electric, and magnetic stimuli. In general, ideal responsive biomaterials exhibit instantaneous and drastic property variation upon light exposure. Depending on the application, a modulation of the response with the light intensity or a reversible property change may also be advantageous. To obtain photoresponsive biomaterials, a photoresponse functional group (chromophore) needs to be incorporated into the polymer chain. Depending on the type of chromophore used, the response can be reversible or irreversible. The reversible change can alternate the material properties in two photostationary states, and hence such materials are used as switches. The reversible chromophores, often named molecular switches, undergo a reversible isomerization upon light excitation at a specific wavelength. The light-induced change of a neutral to a charged system has been applied to control wettability, vesicle dissociation, molecular recognition, polymer chain solubility, and ion penetration. Irreversible chromophores, on the other hand, are mainly applied to photodegradable materials, and these systems are used for drug delivery. The photodegradation leads to effective release of drugs or to drastic decrease of the molecular weight in applications requiring degradation. Special attention is also paid to the supramolecular

265

266

CHAPTER 9 Resorbable polymer matrices

polymers, being one of most relevant developments in recent years. The main applications of these systems include controlled drug delivery and tissue engineering applications. Photobiomedical applications. The photo/light-induced changes in the biomaterials properties can be reflected on macroscopic level, which has been used in various applications such as tissue engineering and drug delivery. Photofabrication technologies are one of the most promising biofabrication strategies for engineering 3D microenvironments for tissue regeneration. The multitude of light-mediated reactions currently available permits the fabrication of highly complex matrices with micro- and nanoscale resolution, exhibiting architectural and compositional features that resemble some of the properties of natural ECM (Pereira and Bartolo, 2015). The photo-controlled techniques in targeted, controlled, and sustained drug delivery with understanding of photoirradiation concept and mechanism are discussed in detail (Shaker and Younes, 2015). In these cases, the light-triggered release system utilizes the photothermal property, which absorbs near-infrared (NIR) light and converts it into heat, thereby inducing the drug release from a thermosensitive carrier. The photothermal with strong optical absorbance in the NIR has been extensively studied for photothermal therapy. Dextran nanogels, pullulan polymer nanogels, and core-shell hybrid nanogels have been studied for the NIR-triggered drug release by incorporation into thermoresponsive materials. However, none of these nanogel delivery systems have been advanced to clinical trials yet. The biomaterials with photolabile groups in the main chain undergo chain breakage upon photo/light and can be classified as photodegradable materials (Cui and Del Campo, 2014; Pereira and Bartolo, 2015). The photolysis requires low energy as a consequence of the ionic photo intermediate instead of a radical. This property makes these systems interesting for biomaterials applications, since the exposure conditions are compatible with living cells. Using scanning lasers and two-photon excitations, micrometric resolution of the photodegradation process was possible. It represents a new generation of photodegradable biomaterials that can be widely used in biocompatible coating, culturing cells, and medical applications.

9.11 Challenges and limitations of resorbable biomaterials The interests in biomedical fields of resorbable biomaterials, particularly chitosansubstituted collagen, are growing due to their potential benefits beyond tissue engineering to enhance physiological performance, like improvements in mechanical strength and biodegradation rates (Raftery et al., 2016). These are usually based on a multiplicity of inter- and intramolecular (noncovalent), covalent interactions, and combined effects of multipoint interactions that may play the most important roles to improve the stability. While, several questions concerning the application of

9.11 Challenges and limitations of resorbable biomaterials

these biomaterials arise like (1) relate to maintain or even improve the biological functions such as biocompatibility, encapsulation, and sustainability of drug and (2) improvement of the physiological functions like cell and tissue adhesion. Several groups have reported resorbable collagen chitosan biomaterials for tissue engineering to be successful (Yin et al., 2014; Zhang et al., 2015a,b; Deepthi et al., 2016; Song et al., 2016; Benzoni et al., 2016). The interaction of collagen with a chitosan to form biomaterials has the most prominent use of building a barrier between the cell and the ECM environment. But these are relatively stiff and thus favor cell adhesion and proliferation. The success of these biomaterials in drug delivery depends mostly on encapsulation efficacy and release profile, which were studied by various research groups (Barroso et al., 2014; Chen et al., 2016; Raftery et al., 2016; Anandhakumar et al., 2017). Sustained release of the encapsulated drug depends mostly on the degradation rate of these biomaterials, giving resorbable biomaterials a remarkable advantage. These materials could offer the following potential advantages for drug delivery: (1) good biocompatibility (cell viability), (2) long-term stability of drugs, (3) protection of the drugs from inhibitors or unfavorable conditions, (4) encapsulation and delivery efficacy, and (5) scalable and robust methods. Because of these aspects, the biomaterials could have a higher degree of biocompatibility when compared to other biomaterials. However, there are still some major challenges that need to be overcome in drug delivery: (1) incorporation of toxic organic solvents, (2) inhibition of the activity of some drugs during fabrication process, (3) release profile depends mostly on degradation rate, (4) encapsulated drug could remain enmeshed within the biomaterials, (5) insufficient initial drug release at the commencement of treatment, and (6) high overdose of the drug may occur during high biomaterial degradation or dissociation. These resorbable biomaterials could be more efficient than the conventional biomaterials, since the latter displays an insufficient drug release profile. These materials maintain their structural integrity and can be used for tissue engineering and drug delivery purposes. Here we highlight new strategies for the development of multifunctionalized resorbable biomaterials to improve the biocompatibility, namely cell viability, adhesion, and proliferations. These materials could provide a gradual transition of the physical, chemical, and mechanical environment and also support the adhesion and proliferation of cells toward the corresponding cellular matrix. Overall, these materials could provide the feasibility for regeneration of hard-to-soft interface tissues. The following strategies will possibly lead to providing multifunctionalized resorbable biomaterials and could open up a new avenue for drug delivery. For example, layer-by-layer assembly of collagen with chitosan to form multifunctionalized resorbable biomaterials could be ideal for cell adhesion and cellular proliferation. The self-assembling ability of collagen on chitosan into fibrous structures permits the construction of well-characterized biomaterials for the study of cell matrix interactions and for their applications in tissue repair. Moreover, the collagen can be embedded in the architecture of chitosan and retain a

267

268

CHAPTER 9 Resorbable polymer matrices

secondary structure close to their native form as well as their bioactivity. The chitosan can interact with collagen of the ECM through integrin receptors. This receptor could involve such fundamental cell processes cell migration, cell growth, and cell differentiations. For drug delivery, (1) functionalized collagen chitosan resorbable biomaterials with stimuli such as temperature/pH, photo/light could be ideal for drug delivery efficacy and (2) photoresponsive and ultrasound resorbable biomaterials could be ideal for depot drug delivery. The above approaches provide information to construct the chitosan-assisted collagen multifunctional biomaterials in optimized conditions, which could be extended to other biomaterials. Moreover, these cover the way to the design of functional biointerfaces in mimicking the structure of the ECM and other constituents including polysaccharides, as well as growth factors or drugs. These approaches are needed to achieve a much better understanding of the basic processes of the multifunctional resorbable biomaterials such as (1) factors important for a desired enzymatic degradation behavior, (2) decisive structural differences between bulk and surface degradable units, (3) interrelations between the degradation characteristics of the biomaterials and the key functional groups, and (4) key differences between hydrolytic and enzymatic degradation. The deeper understanding of the degradation processes will enable the design of advanced resorbable biomaterials whose degradation behavior can be sustainably controlled. The availability of these biomaterials with a reliably controllable degradation rate will contribute substantially to the development of the next generation of biomaterials for tissue implants and drug delivery.

9.12 Concluding remarks and future prospects The resorbable biomaterial chitosan-substituted collagen could provide unique opportunities to mimic the composite with uniform distribution in the ECM environment. The surface, topographical, flexibility, and rigidity properties of these biomaterials can be altered to promote cellular adhesion, differentiation, and migration of virtually any type of cell. Currently the majority of conventional biomaterials are focused on rendering 2D surfaces. However, it is well known that providing a 3D environment to cells has the potential to elicit an optimal response. Modifications in the current methods used to deposit multilayers on 2D substrates will be critical to successful designing of 3D biomaterials. Though biomaterial-based tissue engineering has focused on surface coatings, but architectured biomaterials with collagen and chitosan have the potential for the construction of 3D mimics. These functionalized biomaterials must provide a mechanical support and a physical barrier, but most importantly, they must allow diffusion of signaling molecules to phenotypic maintenance of cells and facilitate cell-to-cell communication. The functionalized biomaterials alter their biological

References

activity to attach a cell, but a carefully chosen combination of the collagen with chitosan pair may result in optimal physiological function. Significant work has been reported on these functionalized resorbable biomaterials for drug delivery. These materials can be easily manipulated, and hence rational design of a new idea to enhance biocompatibility and cell viability is of a great interest. The more advanced types of resorbable biomaterials such as stimuli-responsive, namely, pH-, temperature-, and light-sensitive systems, can enhance the therapeutic efficacy. The use of these biomaterials could add strength while improving the drug release profile, even though a lot of clinical parameters are yet to be investigated. In summary, functionalized biomaterials could be the future of biomedicine, and their potential applications grow linearly with the number of depositions. Tissue regeneration and sustained release of drugs are found to be encouraging, but system improvements such as clinical studies need to be evaluated and optimized. These resorbable biomaterials are versatile, and they may be useful in the future for the management of clinical conditions. Functionalized biomaterials will rapidly expand and provide useful insights into cellular responses to different combinations of physicochemical and biological signals. In the future, these biomaterials will undoubtedly be explored for in vivo applications and clinical trials. Current research and emerging ideas on these hybrid biomaterials will help to achieve new successes in the field of multifunctionalized resorbable biomaterials that could be attractive for tissue regeneration and drug delivery applications.

Acknowledgments We thank the Council of Scientific and Industrial Research and Department of Science and Technology-SERB, Government of India for the DST-SERB Young Scientist Award (GK), for the financial support.

References Ahmadi, A., Vulesevic, B., Ruel, M., Suuronen, E.J., 2013. A collagen-chitosan injectable hydrogel improves vascularization and cardiac remodeling in a mouse model of chronic myocardial infarction. Can. J. Cardiol. 29, S203 S204. Ahmad, M., Nirmal, N.P., Danish, M., Chuprom, J., Jafarzedeh, S., 2016. Characterisation of composite films fabricated from collagen/chitosan and collagen/soy protein isolate for food packaging applications. RSC Adv. 6, 82191 82204. Albanna, M.Z., Bou-Akl, B.H., Walters III, H.L., Matthew, H.W., 2012. Improving the mechanical properties of chitosan-based heart valve scaffolds using chitosan fibers. J. Mechan. Behav. Biomed. Mater. 5, 171 180. Anandhakumar, S., Krishnamoorthy, G., Ramkumar, K.M., Raichur, A.M., 2017. Preparation of collagen peptide functionalized chitosan nanoparticles by ionic gelation

269

270

CHAPTER 9 Resorbable polymer matrices

method: an effective carrier system for encapsulation and release of doxorubicin for cancer drug delivery. Mater. Sci. Eng.: C 70, 378 385. Anitha, A., Sowmya, S., Sudheesh Kumar, P.T., Deepthi, S., Chennazhi, K.P., Ehrlich, H., et al., 2014. Chitin and chitosan in selected biomedical applications. Prog. Polym. Sci. 39, 1644 1667. Arpornmaeklong, P., Suwatwirote, N., Pripatnanont, P., Oungbho, K., 2007. Growth and differentiation of mouse osteoblasts on chitosan collagen sponges. Int. J. Oral Maxillof. Surg. 36, 328 337. Arpornmaeklong, P., Pripatnanont, P., Suwatwirote, N., 2008. Properties of chitosan collagen sponges and osteogenic differentiation of rat-bone-marrow stromal cells. Int. J. Oral. Maxillof. Surg. 37, 357 366. Ashwin, P.T., McDonnell, P.J., 2010. Collagen cross-linkage: a comprehensive review and directions for future research. Br. J. Ophthalmol. 94, 965 970. Bachinger, H.P., Mizuno, K., Vranka, J.A., Boudko, S.P., 2010. Collagen formation and structure, Compre. Nat. Prod II 469 530. Chapter 5.16. Bai, W., Wang, X., Yuan, W., Wang, H., Wang, Z., 2013. Application of PLGA/type I collagen/chitosan artificial composite dura mater in the treatment of dural injury. J. Mater. Sci. Mater. Med. 24, 2247 2254. Barroso, T., Viveiros, T., Casimiro, T., Aguiar-Ricardo, A., 2014. Development of dual-responsive chitosan-collagen scaffolds for pulsatile release of bioactive molecules. J. Supercrit. Fluids 94, 102 112. Benzoni, P., Ginestra, P., Altomare, L., Fiorentino, A., Nardo, L.D., Ceretti, E., et al., 2016. Biomanufacturing of a chitosan/collagen scaffold to drive adhesion and alignment of human cardiomyocyte derived from stem cells. Procedia CIRP 49, 113 120. Bohner, M., 2010. Resorbable biomaterials as bone graft substitutes. Mater. Today 13, 24 30. Buehler, M.J., 2006. Nature designs tough collagen: explaining the nanostructure of collagen fibrils. Proc. Natl. Acad. Sci. U.S.A. 103, 12285 12290. Caldorera-Moore, M., Peppas, N.A., 2009. Micro- and nanotechnologies for intelligent and responsive biomaterial-based medical systems. Adv. Drug Deliv. Rev. 61, 1391 1401. Cao, X., Deng, W., Wei, Y., Yang, Y., Su, W., Wei, Y., et al., 2012. Incorporating pTGF-β1/calcium phosphate nanoparticles with fibronectin into 3-dimensional collagen/chitosan scaffolds: efficient, sustained gene delivery to stem cells for chondrogenic differentiation. Eur. Cell Mater. 23, 81 93. Chakraborty, S., Kumar, M., Suresh, K., Pugazhenthi, G., 2016. Investigation of structural, rheological and thermal properties of PMMA/ONi-Al LDH nanocomposites synthesized via solvent blending method: effect of LDH loading. Chi. J. Polym. Sci. 34, 739 754. Chen, R.N., Wang, G.M., Chen, C.H., Ho, H.O., Sheu, M.T., 2006. Development of N,O(carboxymethyl)chitosan/collagen matrixes as a wound dressing. Biomacromolecules 7, 1058 1064. Chen, Z., Mo, X., He, C., Wang, H., 2008. Intermolecular interactions in electrospun collagen chitosan complex nanofibers. Carbohyd. Polym. 72, 410 418. Chen, K.Y., Liao, W.L., Kuo, S.M., Tsai, F.J., Chen, Y.S., Huang, C.Y., et al., 2009. Asymmetric chitosan membrane containing collagen I nanospheres for skin tissue engineering. Biomacromolecules 10, 1642 1649.

References

Chen, L., Zhu, C., Fan, D., Liu, B., Ma, X., Duan, Z., et al., 2011. A human-like collagen/ chitosan electrospun nanofibrous scaffold from aqueous solution: electrospun mechanism and biocompatibility. J. Biomed. Mater. Res. A 99, 395 409. Chen, T., Li, S., Li, X., Zhang, Y., Huang, Z., Feng, Q., et al., 2012. Noninvasive evaluation of injectable chitosan/nano-hydroxyapatite/collagen scaffold via ultrasound. J. Nanomater. 2012, 1 7. Chen, M.M., Huang, Y.Q., Cao, H., Liu, Y., Guo, H., Chen, L.S., et al., 2015. Collagen/ chitosan film containing biotinylated glycol chitosan nanoparticles for localized drug delivery. Colloids Surf. B: Bioint. 128, 339 346. Chen, Z., Du, T., Tang, X., Liu, C., Li, R., Xu, C., et al., 2016. Comparison of the properties of collagen-chitosan scaffolds after γ-ray irradiation and carbodiimide cross-linking. J. Biomater. Sci. Polym. Ed. 27, 937 953. Chirita, M., 2008. Mechanical properties of collagen biomimetic films formed in the presence of calcium, silica and chitosan. J. Bionic. Eng. 5, 149 158. Chiu, L.L.Y., Radisic, M., 2011. Controlled release of thymosin β4 using collagen chitosan composite hydrogels promotes epicardial cell migration and angiogenesis. J. Control. Release 155, 376 385. Cross, M.C., Toomey, R.G., Gallant, N.D., 2016. Protein-surface interactions on stimuliresponsive polymeric biomaterials. Biomed. Mater. 4 (11), 022002. Cui, J., Del Campo, A., 2014. Chapter 4—Photo-responsive polymers: properties, synthesis and applications. Smart Polymers and their Applications. Woodhead Publishing, pp. 93 133. Deepthi, S., Sundaram, M.N., Deepti Kadavan, J., Jayakumar, R., 2016. Layered chitosancollagen hydrogel/aligned PLLA nanofiber construct for flexor tendon regeneration. Carbohyd. Polym. 53 (2016), 492 500. Ding, C.M., Zhou, Y., He, Y.N., Tan, W.S., 2008. Perfusion seeding of collagen chitosan sponges for dermal tissue engineering. Process Biochem. 43, 287 296. Fan, L., Wu, H., Cao, M., Zhou, X., Peng, M., Xie, W., et al., 2014a. Enzymatic synthesis of collagen peptide carboxymethylated chitosan copolymer and its characterization. React. Funct. Polym. 76, 26 31. Fan, L., Wu, H., Zhou, X., Peng, M., Tong, J., Xie, W., et al., 2014b. Transglutaminasecatalyzed grafting collagen on chitosan and its characterization. Carbohyd. Polym. 105, 253 259. Feng, K.K., Chiang, I.N., 2015. Interaction and function of urothelium and chitosan/collagen tubular scaffold. Urol. Sci. 26, S34. Fernandes, L.L., Resende, C.X., Tavares, D.S., Soares, G.A., Castro, L.O., Granjeiro, J.M., 2011. Cytocompatibility of chitosan and collagen-chitosan scaffolds for tissue engineering. Polı´meros 21, 1 6. Fu, J.H., Zhao, M., Lin, Y.R., Tian, X.D., Wang, Y.D., Wang, Z.X., et al., 2017. Degradable chitosan-collagen composites seeded with cells as tissue engineered heart valves. Heart, Lung Circ. 26, 94 100. Gallyamov, M.O., Chaschin, I.S., Khokhlova, M.A., Grigorev, T.E., Bakuleva, N.P., Lyutova, I.G., et al., 2014. Collagen tissue treated with chitosan solutions in carbonic acid for improved biological prosthetic heart valves. Mater. Sci. Eng. C 37, 127 140. Grumezescu, A.M., Andronescu, E., Ficai, A., Bleotu, C., Mihaiescu, D.E., Chifiriuc, M. C., 2012. Synthesis, characterization and in vitro assessment of the magnetic

271

272

CHAPTER 9 Resorbable polymer matrices

chitosan carboxymethylcellulose biocomposite interactions with the prokaryotic and eukaryotic cells. Int. J. Pharm. 436, 771 777. Grumezescu, A.M., Andronescu, E., Holban, A.M., Ficai, A., Ficai, D., Voicu, G., et al., 2013. Water dispersible cross-linked magnetic chitosan beads for increasing the antimicrobial efficiency of aminoglycoside antibiotics. Int. J. Pharm. 454, 233 240. Haaparanta, A.M., Jarvinen, E., Cengiz, I.F., Ella, V., Kokkonen, H.T., Kiviranta, I., et al., 2014. Preparation and characterization of collagen/PLA, chitosan/PLA, and collagen/ chitosan/PLA hybrid scaffolds for cartilage tissue engineering. J. Mater. Sci. Mater Med. 25, 1129 1136. Hayashi, Y., Yamada, S., Guchi, K.Y., Koyama, Z., Ikeda, T., 2012. Chapter 6—Chitosan and fish collagen as biomaterials for regenerative medicine. Adv. Food Nutr. Res. 5, 107 120. Higuchi, A., Ling, Q.D., Kumar, S.S., Chang, Y., Kao, T.C., Munusamy, M.A., et al., 2014. External stimulus-responsive biomaterials designed for the culture and differentiation of ES, iPS, and adult stem cells. Prog. Polym. Sci. 39, 1585 1613. Hirano, S., Zhang, M., Nakagawa, M., Miyata, T., 2000. Wet spun chitosan collagen fibers, their chemical N-modifications, and blood compatibility. Biomaterials 21, 997 1003. Horn, M.M., Martins, V.C., Plepis, A.,M., 2009. Interaction of anionic collagen with chitosan: effect on thermal and morphological characteristics. Carbohyd. Polym. 77, 239 243. Horn, M.M., Martins, V.C., Plepis, A.M., 2015. Influence of collagen addition on the thermal and morphological properties of chitosan/xanthan hydrogels. Int. J. Biol. Macromol. 80, 225 230. Hou, J., Wang, J., Cao, L., Qian, X., Xing, W., Lu, J., et al., 2012. Segmental bone regeneration using rhBMP-2-loaded collagen/chitosan microspheres composite scaffold in a rabbit model. Biomed. Mater. 7, 035002. Hu, W., Liu, M., Yang, X., Zhang, C., Nie, M., 2019. Modification of chitosan grafted with collagen peptide by enzyme crosslinking. Carbohyd. Polym. 206, 468 475. Huang, C., Chen, R., Ke, Q., Morsi, Y., Zhang, K., Mo, X., 2011a. Electrospun collagen chitosan TPU nanofibrous scaffolds for tissue engineered tubular grafts. Colloids. Surf. B: Biointerf. 82, 307 315. Huang, Z., Yu, B., Feng, Q., Li, S., Chen, Y., Luo, L., 2011b. In situ-forming chitosan/ nano-hydroxyapatite/collagen gel for the delivery of bone marrow mesenchymal stem cells. Carbohyd. Polym. 85, 261 267. Jiang, T.R., James, S.G., Kumbar, C.T.L., 2014. Chapter 5—Chitosan as a biomaterial: structure, properties, and applications in tissue engineering and drug delivery. Natural and Synthetic Biomedical Polymers. Elsevier, pp. 91 113. Jin, G., Prabhakaran, M.P., Liao, S., Ramakrishna, S., 2011. Photosensitive materials and potential of photocurrent mediated tissue regeneration. J. Photochem. Photobiol. B: Biol. 102, 93 101. Jung, U.W., Kim, S.K., Kim, C.S., Cho, K.S., Kim, C.K., Choi, S.H., 2007. Effect of chitosan with absorbable collagen sponge carrier on bone regeneration in rat calvarial defect model. Cur. Appl. Phys. 7, 68 e70. Kakati, K., Pugazhenthi, G., Iyer, P.K., 2012. Effect of organomodified Ni-Al layered double hydroxide (OLDH) on the properties of polypropylene (PP)/LDH nanocomposites. Int. J. Polym. Mater. Polym. Biomater. 61, 931 948.

References

Karaca, S.G., Patir, S., 2016. The use of collagen tripeptide, chitosan and hyaluronic acid based hydrogel for posterolateral lumbar spine fusion. Injury 47, S29. Karri, V.V.S.R., Kuppusamy, G., Talluri, S.V., Mannemala, S.S., Kollipara, R., Wadhwani, A.D., et al., 2016. Curcumin loaded chitosan nanoparticles impregnated into collagenalginate scaffolds for diabetic wound healing. Int. J. Biol. Macromol. 93, 1519 1529. Kim, S.H., Jung, Y., 2013. Chapter 3—Resorbable polymers for medical applications. Biotextiles as Medical Implants. Woodhead Publishing, pp. 91 112. Kishen, A., Shrestha, S., Shrestha, A., Cheng, C., Goh, C., 2016. Characterizing the collagen stabilizing effect of crosslinked chitosan nanoparticles against collagenase degradation. Dent. Mater. 32, 968 977. Kong, Z., Lin, J., Yu, M., Yu, L., Li, J., Weng, W., et al., 2014. Enhanced loading and controlled release of rhBMP-2 in thin mineralized collagen coatings with the aid of chitosan nanospheres and its biological evaluations. J. Mater. Chem. B 2, 4572 4582. Krishnamoorthy, G., Madhan, B., Sadulla, S., Raghava Rao, J., Mathulatha, W., 2008. Stabilization of collagen by plant polyphenolics Acacia mollissima and Terminalia Chebula. J. Appl. Polym. Sci. 108, 199 205. Krishnamoorthy, G., Sehgal, P.K., Mandal, A.B., Sadulla, S., 2011. Protective effect of Withania somnifera and Cardiospermum halicacabum extracts against collagenolytic degradation of collagen. Appl. Biochem. Biotechnol. A: Enzym. Eng. Biotechnol. 165, 1075 1091. Krishnamoorthy, G., Sehgal, P.K., Mandal, A.B., Sadulla, S., 2012. Studies on collagentannic acid-collagenase ternary system: inhibition of collagenase against collagenolytic degradation of extracellular matrix component of collagen. J. Enzyme Inhib. Med. Chem. 27, 451 457. Krishnamoorthy, G., Sehgal, P.K., Mandal, A.B., Sadulla, S., 2013a. Development of Dlysine assisted EDC/NHS initiated crosslinking of collagen matrix for design of scaffold. J. Biomed. Mater. Res., A 101A, 1173 1183. Krishnamoorthy, G., Sehgal, P.K., Sadulla, S., Mandal, A.B., 2013b. Novel collagen scaffolds prepared by using unnatural D-amino acids assisted EDC/NHS crosslinking. J. Biomater. Sci.: Polym. Ed. 24, 344 364. Krishnamoorthy, G., Selvakumar, R., Sastry, T.P., Mandal, A.B., Doble, M., 2013c. Effect of D-amino acids on collagen fibrillar assembly and stability: experimental and modeling studies. Biochem. Eng. J. 75, 92 100. Krishnamoorthy, G., Selvakumar, R., Sastry, T.P., Sadulla, S., Mandal, A.B., Doble, M., 2014. Experimental and theoretical studies on gallic acid assisted EDC/NHS initiated crosslinked collagen scaffolds. Mater. Sci. Eng. C 43, 164 171. Lee, J.E., Kim, K.E., Kwon, I.C., Ahn, H.J., Lee, S.H., Cho, H., et al., 2004. Effects of the controlled-released TGF-beta 1 from chitosan microspheres on chondrocytes cultured in a collagen/chitosan/glycosaminoglycan scaffold. Biomaterials 25, 4163 4173. Lee, J.Y., Kim, K.H., Shin, S.Y., Rhyu, I.C., Lee, Y.M., Park, Y.J., et al., 2006. Enhanced bone formation by transforming growth factor-beta1-releasing collagen/chitosan microgranules. J. Biomed. Mater. Res. A 76, 530 539. Li, M., Han, M., Sun, Y., Hua, Y., Chen, G., Zhang, L., 2019. Oligoarginine mediated collagen/chitosan gel composite for cutaneous wound healing. Int. J. Biol. Macromol. 122, 1120 1127. Lima, C.G.A., de Oliveira, R.S., Figueiro´, S.D., Wehmann, C.F., Goes, J.C., Sombra, A.S. B., 2006. DC conductivity and dielectric permittivity of collagen chitosan films. Mater. Chem. Phys. 99, 284 288.

273

274

CHAPTER 9 Resorbable polymer matrices

Lin, Y.C., Tan, F.J., Marra, K.G., Jan, S.S., Liu, D.C., 2009. Synthesis and characterization of collagen/hyaluronan/chitosan composite sponges for potential biomedical applications. Acta Biomater. 5, 2591 2600. Liu, Y., Ma, L., Gao, C., 2012. Facile fabrication of the glutaraldehyde cross-linked collagen/chitosan porous scaffold for skin tissue engineering. Mater. Sci. Eng.: C 32, 2361 2366. Liu, X., Ma, L., Liang, J., Zhang, B., Teng, J., Gao, C., 2013. RNAi functionalized collagen-chitosan/silicone membrane bilayer dermal equivalent for full-thickness skin regeneration with inhibited scarring. Biomaterials 34, 2038 2048. Ma, L., Gao, C., Mao, Z., Zhou, J., Shenm, J., Hu, X., et al., 2003. Collagen/chitosan porous scaffolds with improved biostability for skin tissue engineering. Biomaterials 24, 4833 4841. Ma, X., Deng, J., Du, Y., Li, X., Fan, D., Zhu, C., et al., 2014. A novel chitosan collagenbased hydrogel for use as a dermal filler: initial in vitro and in vivo investigations. J. Mater. Chem. B 2, 2749 2763. Madhan, B., Krishnamoorthy, G., Raghava Rao, J., Nair, B.U., 2007. Role of green tea polyphenols in the inhibition of collagenolytic activity by collagenase. Int. J. Biol. Macromol. 41, 16 22. Mahmoud, A.A., Salama, A.H., 2016. Norfloxacin-loaded collagen/chitosan scaffolds for skin reconstruction: preparation, evaluation and in-vivo wound healing assessment. Eur. J. Pharm. Sci. 83, 155 165. Maitz, M.F., 2015. Applications of synthetic polymers in clinical medicine. Biosurf. Biotribol. 1, 161 176. Martı´nez, A., Blanco, M.D., Davidenko, N., Cameron, R.E., 2015. Tailoring chitosan/collagen scaffolds for tissue engineering: effect of composition and different crosslinking agents on scaffold properties. Carbohyd. Polym. 132, 606 619. Meinig, R.P., 2010. Clinical use of resorbable polymeric membranes in the treatment of bone defects. Orthop. Clin. N. Am. 41, 39 47. Meyer, C., Stenberg, L., Gonzalez-Perez, F., Wrobel, S., Ronchi, G., Udina, E., et al., 2016. Chitosan-film enhanced chitosan nerve guides for long-distance regeneration of peripheral nerves. Biomaterials 76, 33 51. Mogosanu, G.D., Grumezescu, A.M., 2014. Natural and synthetic polymers for wounds and burns dressing. Int. J. Pharm. 463, 127 136. Mogosanu, G.D., Grumezescu, A.M., Bejenaru, L.E., Bejenaru, C., 2016. Chapter 8— Natural and synthetic polymers for drug delivery and targeting. Nanobiomaterials in Drug Delivery Eds: Alexandru Mihai Grumezescu, Elsevier, Volume 9. pp. 229 284. Moreira, C.D., Carvalho, S.M., Mansur, H.S., Pereira, M.M., 2016. Thermogelling chitosan collagen bioactive glass nanoparticle hybrids as potential injectable systems for tissue engineering. Mater. Sci. Eng. C 58, 1207 1216. Munhoz, M.A.S., Hirata, H.H., Plepis, A.M.G., Martins, V.C.A., Cunha, M.R., 2018. Use of collagen/chitosan sponges mineralized with hydroxyapatite for the repair of cranial defects in rats. Injury 49, 2154 2160. S0020-1383, 30520-30525. Nair, L.S., Laurencin, C.T., 2007. Biodegradable polymers as biomaterials. Prog. Polym. Sci. 32, 762 798. Pereira, R.F., Bartolo, P.J., 2015. 3D Photo-fabrication for tissue engineering and drug delivery. Engineering 1, 090 112.

References

Pon-On, W., Charoenphandhu, N., Teerapornpuntakit, J., Thongbunchoo, J., Krishnamra, N., Tang, I.M., 2014. Mechanical properties, biological activity and protein controlled release by poly(vinyl alcohol) bioglass/chitosan collagen composite scaffolds: a bone tissue engineering applications. Mater. Sci. Eng.: C 38, 63 72. Purcel, G., Meli¸ta, D., Andronescu, E., Grumezescu, A.M., 2016. Chapter 7—Collagenbased nanobiomaterials: challenges in soft tissue engineering. Nanobiomaterials in Soft Tissue Engineering. Eds; Alexandru Mihai Grumezescu, Elsevier, Volume 5 pp. 173 200. Radulescu, D., Grumezescu, V., Andronescu, E., Holban, A.M., Grumezescu, A.M., Socol, G., et al., 2016. Biocompatible cephalosporin-hydroxyapatite-poly(lactic-co-glycolic acid)-coatings fabricated by MAPLE technique for the prevention of bone implant associated infections. Appl. Surf. Sci. 374, 387 396. Rafat, M., Li, F., Fagerholm, P., Lagali, N.S., Watsky, M.A., Munger, R., et al., 2008. PEG-stabilized carbodiimide crosslinked collagen chitosan hydrogels for corneal tissue engineering. Biomaterials 29, 3960 3972. Raftery, R.M., Tierney, E.G., Curtin, C.M., Cryan, S.A., O’Brien, F.J., 2015. Development of a gene-activated scaffold platform for tissue engineering applications using chitosanpDNA nanoparticles on collagen-based scaffolds. J. Control. Release 210, 84 94. Raftery, R.M., Woods, B., Marques, A.L.P., Moreira-Silva, J., Silva, T.H., Cryan, S.A., et al., 2016. Multifunctional biomaterials from the sea: assessing the effects of chitosan incorporation into collagen scaffolds on mechanical and biological functionality. Acta Biomater. 43, 160 169. Ramasamy, P., Shanmugam, A., 2015. Characterization and wound healing property of collagen chitosan film from sepia kobiensis (Hoyle, 1885). Int. J. Biol. Macromol. 74, 93 102. Rao, R.R., Jiao, A., Kohn, D.H., Stegemann, J.P., 2012. Exogenous mineralization of cellseeded and unseeded collagen chitosan hydrogels using modified culture medium. Acta Biomater. 8, 1560 1565. Reis, L.A., Loraine, L.Y., Chiu, Y., Liang, K., Hyunh, Momen, A., et al., 2012. A peptidemodified chitosan collagen hydrogel for cardiac cell culture and delivery. Acta Biomater. 8, 1022 1036. Sahu, B., Pugazhenthi, G., 2012. Characterization of polystyrene (PS)/organomodified layered double hydroxide (OLDH) nanocomposites prepared by in situ polymerization. Adv. Mater. Res. 410, 164 167. Sang, L.Y., Zhou, X.H., Yun, F., Zhang, G.L., 2010. Enzymatic synthesis of chitosangelatin antimicrobial copolymer and its characterisation. J. Sci. Food Agric. 90, 58 64. Shaker, M.A., Younes, H.M., 2015. Photo-irradiation paradigm: mapping a remarkable facile technique used for advanced drug, gene and cell delivery. J. Control. Release 217, 10 26. Silva, C.C., Lima, C.G.A., Pinheiro, A.G., Goes, J.C., Figueiro, S.D., Sombra, A.S.B., 2001. On the piezoelectricity of collagen chitosan films. Phys. Chem. Chem. Phys. 3, 4154 4157. Sionkowska, A., 2006. Effects of solar radiation on collagen and chitosan films. J. Photochem. Photobiol. B: Biol. 82, 9 15. Sionkowska, A., Wisniewski, M., Skopinska, J., Kennedy, Wess, T.J., 2004. The photochemical stability of collagen chitosan blends. J. Photochem. Photobiol. A: Chem. 162, 545 554.

275

276

CHAPTER 9 Resorbable polymer matrices

Sionkowska, A., Wisniewski, M., Skopinska, J., Poggi, G.F., Marsano, E., Maxwell, C.A., et al., 2006. Thermal and mechanical properties of UV irradiated collagen/chitosan thin films. Polym. Degrad. Stab. 91, 3026 3032. Sionkowska, A., Kaczmarek, B., Lewandowska, K., 2014. Modification of collagen and chitosan mixtures by the addition of tannic acid. J. Mol. Liq. 199, 318 323. Sionkowska, A., Kaczmarek, B., Lewandowska, K., Grabska, S., Pokrywczynska, M., Kloskowski, T., et al., 2016. 3D composites based on the blends of chitosan and collagen with the addition of hyaluronic acid. Int. J. Biol. Macromol. 89, 442 448. Song, Y., Zhang, D., Lv, Y., Guo, X., Lou, R., Wang, S., et al., 2016. Microfabrication of a tunable collagen/alginate-chitosan hydrogel membrane for controlling cell cell interactions. Carbohyd. Polym. 153, 652 662. Song, K., Li, L., Yan, X., Zhang, W., Zhang, Y., Wang, Y., et al., 2017. Characterization of human adipose tissue-derived stem cells in vitro culture and in vivo differentiation in a temperature-sensitive chitosan/β-glycerophosphate/collagen hybrid hydrogel. Mater. Sci. Eng: C 70, 231 240. Sun, H., Wang, X., Hu, X., Yu, W., You, C., Hu, H., et al., 2012. Promotion of angiogenesis by sustained release of rhGM-CSF from heparinized collagen/chitosan scaffolds. J. Biomed. Mater. Res. B Appl. Biomater. 100, 788 798. Suresh, K., Boro, R., Vinoth Kumar, R., Pugazhenthi, G., 2016. Effect of concentration and temperature on rheological behaviour of polystyrene solution. Macromol. Symp. 362, 87 100. Tangsadthakun, C., Kanokpanont, S., Sanchavanakit, N., Pichyangkura, R., Banaprasert, T., Tabata, Y., et al., 2007. The influence of molecular weight of chitosan on the physical and biological properties of collagen/chitosan scaffolds. J. Biomat. Sci. Polym. Ed. 18, 147 163. Tomoaia, G., Soritau, O., Tomoaia-Cotisel, M., Pop, L.B., Pop, A., Mocanu, A., et al., 2013. Scaffolds made of nanostructured phosphates, collagen and chitosan for cell culture. Powder Technol. 238, 99 107. Uriarte-Montoya, M.H., Arias-Moscoso, J.L., Plascencia-Jatomea, M., Santacruz-Ortega, H., Rouzaud-Sa´ndez, O., Cardenas-Lopez, J.L., et al., 2010. Jumbo squid (Dosidicus gigas) mantle collagen: extraction, characterization, and potential application in the preparation of chitosan collagen biofilms. Bioresour. Technol. 101, 4212 4219. Valapa, R., Pugazhenthi, G., Katiyar, V., 2014. Thermal degradation kinetics of sucrose palmitate reinforced poly (lactic acid) biocomposites. Int. J. Biol. Macromol. 65, 275 283. Valapa, R., Pugazhenthi, G., Katiyar, V., 2016a. Hydrolytic degradation behaviour of sucrose palmitate reinforced poly(lactic acid) nanocomposites. Int. J. Biol. Macromol. 89, 70 80. Valapa, R.S., Hussain, Iyer, P.K., Pugazhenthi, G., Katiyar, V., 2016b. Non-isothermal crystallization kinetics of sucrose palmitate reinforced poly(lactic acid) bionanocomposites. Polym. Bul 73, 21 38. Wan, Y., Huang, J., Zhang, J., Yin, D., Zheng, Z., Liao, C., et al., 2013. Investigation of mechanical properties and degradability of multi-channel chitosan-polycaprolactone/ collagen conduits. Polym. Degrad. Stab. 98, 122 132. Wang, X.H., Li, D.P., Wang, W.J., Feng, Q.L., Cui, F.Z., Xu, Y.X., et al., 2003. Crosslinked collagen/chitosan matrix for artificial livers. Biomaterials 24, 3213 3220.

References

Wang, X., Yan, Y., Xiong, Z., Lin, F., Wu, R., Zhang, R., et al., 2005. Preparation and evaluation of ammonia-treated collagen/chitosan matrices for liver tissue engineering. J. Biomed. Mater. Res. B: Appl. Biomater. 75, 91 98. Wang, C.C., Wu, W.Y., Chen, C.C., 2011a. Antibacterial and swelling properties of N-isopropyl acrylamide grafted and collagen/chitosan-immobilized polypropylene nonwoven fabrics. J. Biomed. Mater. Res. B: Appl. Biomater. 96, 16 24. Wang, X., Sang, L., Luo, D., Li, X., 2011b. From collagen chitosan blends to threedimensional scaffolds: the influences of chitosan on collagen nanofibrillar structure and mechanical property. Colloids Surf. B: Biointerf. 82, 233 240. Wang, X., Li, Q., Hu, X., Ma, L., You, C., Zheng, Y., et al., 2012. Fabrication and characterization of poly(L-lactide-co-glycolide) knitted mesh-reinforced collagen chitosan hybrid scaffolds for dermal tissue engineering. J. Mech. Behav. Biomed. Mater 8, 204 215. Wang, X., You, C., Hu, X., Zheng, Y., Li, Q., Feng, Z., et al., 2013. The roles of knitted mesh-reinforced collagen chitosan hybrid scaffold in the one-step repair of fullthickness skin defects in rats. Acta Biomater. 9, 7822 7832. Wang, C., Xie, X.D., Huang, X., Liang, Z.H., Zhou, C.R., 2015. A quantitative study of MC3T3-E1 cell adhesion, morphology and biomechanics on chitosan collagen blend films at single cell level. Colloids Surf. B: Biointerf. 132, 1 9. Wang, X., Wu, P., Hu, X., You, C., Guo, R., Shi, H., et al., 2016. Polyurethane membrane/ knitted mesh-reinforced collagen-chitosan bilayer dermal substitute for the repair of full-thickness skin defects via a two-step procedure. J. Mech. Behav. Biomed. Mater. 56, 120 133. Wlaszczuk, A., Marcol, W., Kucharska, M., Wawro, D., Palen, P., Lewin-Kowalik, J., 2016. Poly(D,L-lactide-co-glycolide) tubes with multifilament chitosan yarn or chitosan sponge core in nerve regeneration. J. Oral Maxillof. Surg. 74, 2327.e1 2327.e12. Wu, T., Jiang, B., Wang, Y., Yin, A., Huang, C., Wang, S., et al., 2015. Electrospun poly (L-lactide-co-caprolactone) collagen chitosan vascular graft in a canine femoral artery model. J. Mater. Chem. B 3, 5760 5768. Yan, L.P., Wang, Y.J., Ren, L., Wu, G., Caridade, S.G., Fan, J.B., et al., 2010. Genipincross-linked collagen/chitosan biomimetic scaffolds for articular cartilage tissue engineering applications. J. Biomed. Mater. Res. A 95, 465 475. Ye, Y., Dan, W., Zeng, R., Lin, H., Dan, N., Guan, L., et al., 2007. Miscibility studies on the blends of collagen/chitosan by dilute solution viscometry. Eur. Polym. J. 43, 2066 2071. Yin, A., Zhang, K., McClure, M.J., Huang, C., Wu, J., Fang, J., et al., 2013. Electrospinning collagen/chitosan/poly(L-lactic acid-co-ε-caprolactone) to form a vascular graft: mechanical and biological characterization. J. Biomed. Mater. Res. A 101A, 1292 1301. Yin, D., Wu, H., Liu, C., Zhang, J., Zhou, T., Wu, J., et al., 2014. Fabrication of composition-graded collagen/chitosan polylactide scaffolds with gradient architecture and properties. React. Funct. Polym. 83, 98 106. Zhang, Y., Reddy, V.J., Wong, S.,Y., Li, X., Su, B., Ramakrishna, S., et al., 2010. Enhanced biomineralization in osteoblasts on a novel electrospun biocomposite nanofibrous substrate of hydroxyapatite/collagen/chitosan. Tissue Eng., A 16, 1949 1960. Zhang, J., Liu, G., Wu, Q., Zuo, J., Qin, Y., Wang, J., 2012. Novel mesoporous hydroxyapatite/chitosan composite for bone repair. J. Bionic. Eng. 9, 243 251.

277

278

CHAPTER 9 Resorbable polymer matrices

Zhang, J., Deng, A., Yang, Y., Gao, L., Xu, N., Liu, X., et al., 2015a. HPLC detection of loss rate and cell migration of HUVECs in a proanthocyanidin cross-linked recombinant human collagen-peptide (RHC) chitosan scaffold. Mater. Sci. Eng. C 56, 555 563. Zhang, Q., Hubenak, J., Iyyanki, T., Alred, E., Turza, K.C., Davis, G., et al., 2015b. Engineering vascularized soft tissue flaps in an animal model using human adipose derived stem cells and VEGF 1 PLGA/PEG microspheres on a collagen-chitosan scaffold with a flow-through vascular pedicle. Biomaterials 73, 198 213. Zhu, Y., Wan, Y., Zhang, J., Yin, D., Cheng, W., 2014. Manufacture of layered collagen/ chitosan-polycaprolactone scaffolds with biomimetic microarchitecture. Colloids Surf. B: Biointerf. 113, 352 360.

Further reading Wang, L., Stegemann, J.P., 2010. Thermogelling chitosan and collagen composite hydrogels initiated with β-glycerophosphate for bone tissue engineering. Biomaterials 31, 3976 3985. Wang, L., Stegemann, J.P., 2011. Glyoxal crosslinking of cell-seeded chitosan/collagen hydrogels for bone regeneration. Acta Biomater. 7, 2410 2417. Wang, W., Lin, S., Xiao, Y., Huang, Y., Tan, Y., Cai, L., et al., 2008. Acceleration of diabetic wound healing with chitosan-crosslinked collagen sponge containing recombinant human acidic fibroblast growth factor in healing-impaired STZ diabetic rats. Life Sci. 82, 190 204.