Chitosan–hyaluronic acid composite sponge scaffold enriched with Andrographolide-loaded lipid nanoparticles for enhanced wound healing

Accepted Manuscript Title: Chitosan–Hyaluronic acid composite sponge scaffold enriched with Andrographolide-loaded lipid nanoparticles for enhanced wound healing Authors: Rania Abdel-Basset Sanad, Hend Mohamed Abdel-Bar PII: DOI: Reference:

S0144-8617(17)30623-9 http://dx.doi.org/doi:10.1016/j.carbpol.2017.05.098 CARP 12384

To appear in: Received date: Revised date: Accepted date:

2-3-2017 25-4-2017 31-5-2017

Please cite this article as: Sanad, Rania Abdel-Basset., & Abdel-Bar, Hend Mohamed., Chitosan–Hyaluronic acid composite sponge scaffold enriched with Andrographolideloaded lipid nanoparticles for enhanced wound healing.Carbohydrate Polymers http://dx.doi.org/10.1016/j.carbpol.2017.05.098 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Chitosan–Hyaluronic acid composite sponge scaffold enriched with Andrographolide-loaded lipid nanoparticles for enhanced wound healing.

Rania Abdel-Basset Sanad a,*, Hend Mohamed Abdel-Barb a

Department of Pharmaceutics, National Organization for Drug Control and Research (NODCAR),

Giza, Egypt. (E-mail: [email protected]) b

Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, University of Sadat

city, Egypt. (E-mail: [email protected]) * Corresponding author at: Department of Pharmaceutics, National Organization for Drug Control and Research (NODCAR), Cairo, Egypt, 6 Abou Hazem Street, Pyramids,Giza, Egypt; Tel: +002 01224980700; e-mail: [email protected] Highlights    

Andrographolide lipid nanoparticles were prepared and statistically optimized.  Chitosan-hyaluronan/Andrographolide nanocomposite scaffold was successfully prepared.  Addition of Andrographolide nanocarrier showed proper porosity and swelling ratio.  Chitosan-hyaluronan/Andrographolide scaffold showed enhanced wound healing capacity.

Abstract In this work chitosan–hyaluronic acid composite sponge scaffold enriched with andrographolide (AND) lipid nanocarriers was developed. Nanocarriers were prepared using solvent diffusion method by applying 23 factorial design. NLC4 had the highest desirability value (0.882) and therefore, it was chosen as an optimal nanocarrier. Itexhibited spherical shape with

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253 nm, 83.04% entrapment efficiency and a prolonged release of AND up to 48-h. Consecutively, NLC4 was incorporated in a chitosan-hyaluronic acid gel and lyophilized for 24 h to obtain chitosan-hyaluronic acid/NLC4 nanocomposite sponge to enhance AND delivery to wound sites. The morphology of sponge was characterized by scanning electron microscopy. Nanocomposites showed a porosity of 56.22%with enhanced swelling. The in vivo evaluation in rats reveals that the chitosan-hyaluronic acid/NLC4 sponge enhances the wound healing with no scar and improved tissue quality. These results strongly support the possibility of using this novel chitosan-HA/NLC4 sponge for wound care application. Keywords: Chitosan; hyaluronic acid;andrographolide; lipid nanoparticles; sponge scaffold; in vivo wound healing. 1.

Introduction

Chitosan is a unique biodegradable, biocompatible polymer possessing hemostatic properties which make it a prospective candidate in the wound healing substrates (Deng, He, Zhao, Yang, & Liu, 2007). It could be applied in wound healing sponge scaffolds (Lu et al., 2017) which should be non-toxic, non-allergic and allow proper nutrient and gas exchange (Jayakumar, Prabaharan, Sudheesh Kumar, Nair, & Tamura, 2011). Due to their well-interconnected microporous structure, chitosan sponges have good cell interaction, fluid absorption capability, and hydrophilicity (Anisha et al., 2013b). Unfortunately, the high brittleness of chitosan is the most pronounced inadequacy in formulating wound healing materials, which could be overcome by blending them with other polymers (Han et al., 2014) such as Hyaluronic acid (HA) (Mohandas, Anisha, Chennazhi, & Jayakumar, 2015a). HA is the main constituent of the skin extracellular matrix with good hydrophilic property. It provides a moist environment and protects the wounded tissue surface from dryness and encourages healing. Besides, it enhances collagen secretion at the 2

wound site by fibroblast proliferation and have an optimistic effect in scarless wound healing (Anisha, Biswas, Chennazhi & Jayakumar, 2013a).Utilizing these polymers to produce improved wound management products especially those based on natural medicines represents an essential research area (Boateng and Catanzano, 2015). Andrographolide (AND) is a natural diterpene lactone separated from Andrographis paniculata leaves with improved wound healing activity in rats (Al-Bayaty, Abdulla, Abu Hassan& Ali, 2012). This could be due to the reported antiinflammatory and antioxidant activities of AND (Li, Hu, Sun, Luo, Lu, & Tian, 2016). These could play a significant role in protecting the tissues from oxidative damage and developing the woundhealing process (Al-Bayaty, Abdulla, Abu Hassan& Ali, 2012). However, formulation development of AND has been limited by its poor aqueous solubility (Jiang et al., 2014). Therefore, encapsulation of AND in a nanoparticle platform can overcome the aforementioned shortcoming to an extent. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) applied in the treatment of wounds could selectively permeabilize the stratum corneum, and also afford sufficient drug localization and deposition (Pachuau, 2015). However, as SLN and NLC suspensions do not acquire sufficient viscosity to encourage its use for topical application. Therefore, the inclusion of these active nanoparticles in secondary vehicles such as scaffolds to elaborate their application and dosage, enhance the beneficial effects of the formulations, microenvironment protection, enhance the consistency of final formulations, co-delivery of active molecules at target sites and promote the long-term stability of the incorporated nanoparticles (Oyarzun-Ampuero et al., 2015). Yet, there is no published work used AND in a wound healing nanocomposite sponge scaffold. The novelty of this work is to exploit the lucid biocompatibility and biodegradability of chitosan-HA scaffold loaded with the antioxidant and anti-inflammatory AND lipid nanocarrier as

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an innovative wound healing agent. To the best of our knowledge, although chitosan-HA sponges enriched with nanoparticles proved their high efficiency in wound healing, but yet there is no published work deal with enrichment of these chitosan sponge scaffolds with NLCs. Moreover, AND has not been formulated in NLCs before. Consequently, this in vitro and in vivo study aimed to evaluate the wound healing efficiency of chitosan- HA sponge scaffold enriched with ANDNLCs. 2. Materials and methods 2.1. Materials Chitosan (MW 100–150 kDa, degree of deacetylation-85%) was purchased from Koyo Chemical Co., Ltd. (Japan). Hyaluronic acid (HA) (MW 1500-1800 KDa) was purchased from Qingdao Haitao Biochemical Co., Ltd. (China). AND (Xi'an Sonwu Biotech Co.,Ltd., China). Solid lipids: Cetyl palmitate and Geleol, liquid lipid: Labrafac lipophile WL1349 (medium chain triglyceride) (Gattefossè, France). Tego care 450 (polyglyceryl-3 methylglucose distearate) was obtained from Goldschmidt, Germany). Brij 58 (Polyoxyethylene 20 cetyl ether) (Acros Organic, Morris Plains, NJ). All other reagents were of analytical grade. 2.2. Chemical compounds studied in this article Chitosan (CID: 71853); Hyaluronic acid (CID: 24728612); Andrographolide (CID: 5318517); Cetyl palmitate (CID: 10889); Labrafac (CID: 198429); Brij 58 (CID: 2724259). 2.3. Methods 2.3.1. Preparation of SLNs and NLCs AND-loaded SLNs and NLCs were prepared by solvent diffusion method (Sanad, Abdelmalak, Elbayoomy, & Badawi, 2010). Briefly, the lipid phase (7% w/w of the formulation) composed of cetyl palmitate or Geleol with or without Labrafac lipophile WL1349 and AND (2% 4

w/w of the formulation) were completely dissolved in a mixture of acetone and ethanol 1:1 (v/v) at 50°C. The resultant lipid solution was poured into 120 mL of an aqueous phase containing 2% surfactant (tego care 450 or Brij 58) under agitation by mechanical stirrer (Falc Instruments, Italy) at 400 rpm at 70°C for 5 min. The obtained dispersion was cooled to room temperature to obtain AND-nanoparticles. The drug-free nanoparticles were also prepared. The composition of the prepared nanoparticles is given in Table 1. *

Percent with respect to total lipid concentration.

2.3.2. Optimization of nanoparticle formulations 23 full-factorial design was used to optimize the variables for the preparation of AND lipid carriers. Dependent, independent variables and the desirability constraints are shown in Table 2. The statistical analysis of responses was made by Design-Expert®7 Soft-ware (Stat-Ease Inc., Minneapolis, MN, USA). 2.4. In-vitro characterization of SLNs and NLCs 2.4.1. Particle Size (PS) analysis PS and the polydispersity index (PDI) of the nanoparticles were determined by using laser scattering particle size analyzer (LA-920, Horiba, Japan) 2.4.2. Entrapment efficiency (EE %) and drug loading (DL) AND nanoparticle suspensions were diluted 1:9 (v/v) in ethanol and put into a Pall Nanosep® MF centrifugal device with Bio-Inert membrane pore size 0.2 μm (Sigma Aldrich, India), then centrifuged (Hermle Z 326 K, Hermle Labortechnik GmbH, Germany) at 8,000 rpm for 60 min at 10ºC. The supernatants were then analyzed for AND content by measuring at 225 nm using spectrophotometer (Shimadzu Co., Kyoto, Japan). EE and DL were then calculated (Moreno-Sastre et al., 2016): EE%= (Di– Dn)/Di×100

(1) 5

DL = (Di - Dn)/L X 100

(2)

Di: initial drug amount Dn: unentrapped drug. L: total lipid. 2.4.3. In vitro drug release AND-nanoparticles or drug suspension equivalent to 4mg drug were put into the dialysis bags (molecular weight cutoff 12–14 kDa; Serva Electrophoresis GmbH, Germany) which placed in 500 mL PBS, pH 7.4 (Yang et al., 2013), at 37ºC and stirred at 100 rpm for 48 h. Samples were withdrawn at 1, 2, 3, 4, 5, 6, 7, 8, 24 and 48 h and then AND was quantified by UPLC system (Waters Corporation, USA). The chromatographic analysis was performed using a BEH300 C 18 (1.7 μm 2.1 × 50 mm) column. The mobile phase was: water and methanol (50:50, v/v). The flow rate was 0.1 mL/min; the injection volume was 10 μl and UV detection at 227 nm was used (Du et al., 2012).The coefficient of determination (R2) of the AND calibration curve in PBS in the concentration range of 0.2–50 µg/mL, was 0.9994 and the respective limits of detection (LOD) and quantification (LOQ) were 0.08 and 0.2 µg/mL. The CV% ranged from 0.85 to 9.78% and the accuracy for AND determination was within acceptable range (not more than 1%) with mean% drug recovery of 99.68%. In vitro drug release data was fitted to various kinetic models and the regression analysis was performed. 2.5. Selection of the optimized formulation Design Expert software was utilized for the selection of optimized formulation with small particle size, higher in vitro cumulative drug release after 48 h, and higher EE%. (Tiwari & Pathak, 2011) 2.6. Transmission Electron Microscope (TEM)

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The morphology of the optimized AND nanoparticles was inspected by TEM (JEOL, JEMHR-2100, Japan). Nanoparticles were dried on a carbon coated copper 300-mesh grid and stained with 2% phosphotungstic acid and visualized at 200 kV. 2.7. Preparation of chitosan–HA/AND-nanoparticle scaffold Chitosan–HA scaffold enriched with AND-nanoparticle was prepared in two steps. First, chitosan-HA blend was prepared by mixing solution 1 (2% w/v chitosan dissolved in 1% acetic acid) with solution 2 (1% w/v HA dissolved in double distilled water) in a ratio 2:1 (Anisha, Biswas, Chennazhi & Jayakumar, 2013). Subsequently, the optimized lipid nanoparticle dispersion was added to the chitosan–HA blend in a ratio 3:7, and stirred for 4 h to obtain a homogenous mixture which was poured into a mold, frozen and lyophilized for 24 h. 2.8. Characterization of chitosan–HA/AND-nanoparticle scaffold. 2.8.1. Fourier- Transformed Infrared spectroscopy (FT-IR) FTIR spectra of Chitosan, HA, and chitosan-HA scaffold, were recorded on a FT/IR-4100 FT-IR (JASCO, Tokyo, Japan). IR spectra were obtained over the range 450–4000 cm−1. 2.8.2. Morpholgy The morphology of chitosan-HA scaffold and chitosan-HA/AND-nanoparticle scaffold was observed by scanning electron microscopy (Quanta 250 FEG, FEI Co) under low vacuum at 400x magnification. TEM was used for examining the integrity of the optimized ANDnanoparticle in sponge by dispersing it in water, sonicated for 15 minutes, and then treated similarly as described under section (2.6) (Hazzah, Farid, Nasra, EL-Massik & Abdallah, 2015). 2.8.3. Porosity

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Samples of identified volume (V) and weight (Wi) were dipped in a graduated cylinder containing ethanol and soaked for 24 h (Loh and Choong, 2013). The final weight of the wet scaffold was noted as Wf. Porosity % was determined: Porosity%= ((Wf – Wi / ρ ethanol)/V)X 100

(3)

ρ ethanol: Density of ethanol. 2.8.4. Swelling ratio Scaffolds were immersed in PBS (pH 7.4) for different time points and incubated at 37°C. Swelling ratio was calculated: Swelling ratio= Ww-Wi/Wi

(4)

Where Wi is the initial weight of the scaffolds and Ww is the wet weight of the samples after taking them out and removing the excess buffer from them. 2.8.5. In vitro release of AND sponge: A sponge equivalent to 4 mg AND was transferred to a dialysis bag (cutoff 12-14 KDa) and immersed into 500 mL PBS pH 7.4 and the release study was conducted as previously discussed (section 2.4.3.) up to 72 h. 2.8.6. Antioxidant Activity The antioxidant activity of nonmedicated and medicated scaffolds was determined by using DPPH as free radical (Rossi et al., 2007). Briefly, 20 mg of each scaffold was added to 975 μL of a 6 ×10−5 mol-1 methanol/KH2PO4/NaOH buffer (50:50 v/v) DPPH solution, shaken and allowed to stand at room temperature in the dark for 100 min. The absorbance of each sample was determined at 517 nm using a UV VIS spectrophotometer (UV-2450; Shimadzu Co., Kyoto, Japan). The control was prepared by mixing methanol/ KH2PO4/ NaOH buffer and DPPH radical solution. The DPPH scavenged activity percentage (AA%) was determined:

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DPPH scavenged %= A con - A test / A con X 100

(5)

A con : absorbance of the control. A test : is the absorbance in the presence of the sample of examined sponge. 2.9. In-vivo wound healing study. 2.9.1. Animals The Ethics Committee at the National Organization for Drug Control and Research, Giza, Egypt approved all experiments. Six male albino rats (220 - 240 g) were kept in separate cages with free access to food and water at a 12 h light/12 h dark cycle in a temperature controlled room at 25±1°C. Rats were anesthetized by intraperitoneal thiopental injection (100 mg/kg) immediately before inflicting the burn. The hair of each rat dorsum was shaved and cleaned with 70% ethanol. 2.9.2. Burn-wound model The back of each rat was exposed for 5 s to stainless steel stamp heated for 5 min to form a second degree burn wound (Morsi, Abdelbary, & Ahmed, 2014). Each rat was subjected to three burns, the first was treated with chitosan-HA scaffold, the second treated with the chitosanHA/AND-nanoparticle scaffold and the third wound was kept without treatment as control. After applying each scaffold on the burn-wounds, the wounds were covered by Tegaderm® (3 M Health Care, Germany). Scaffolds were applied every other day to the burned areas for 21 days. On 1st, 4th, 12th and 21st post wounding days, the appearance of the wound was photographed. Tracing the margin of the wound area onto the wound-photograph was performed by using 10.0 Adobe Photoshop CS3 Extended software. The relative wound size reduction was determined (Anjum, Arora, Alam & Gupta, 2016): The relative wound size reduction (%) = (Ao-At)/ Ao X 100

(6)

A0 and At: the wound areas one day after operation and the specified day, respectively.

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2.9.3. Histopathological examination At the 1st and 21st day after wound treatment, collection of full thickness skin biopsies of wounds was done. Samples were fixed in 10% formol saline for 24h, washed by tap water and dehydrated by serial dilutions of alcohol. Specimens were cleared in xylene and inserted in paraffin for 24h in hot air oven at 56°, cut into 4 µm thickness pieces, stained by hematoxylin & eosin (H&E) and subsequently visualized under a light electric microscope. 2.10. Statistical analysis All presented in vitro data are the mean of three replicates ±SD and in vivo data are the mean of six replicates ±SD. For comparing two variables, student’s t-test was applied. To compare difference between groups, one-way analysis of variance (ANOVA) was applied followed by Tukey HSD test (SPSS 18, Chicago, USA.), differences were considered statistically significant at p≤0.05. 3. Results and discussion 3.1. Nanoparticle characterization 3.1.1. PS The mean size of the prepared nanoparticles was shown in Table 3. Fig. 1a shows the effect of the three independent variables on the PS. Geleol formed significantly (P < 0.0001) smaller nanoparticles as it contains monoglycerides that possesses surfactant properties (Jensen, L. B., Magnussson, Gunnarsson, Vermehren, Nielsen, & Petersson, 2010). In the existence of water, Geleol will rearrange into the aqueous–organic interface and facilitates emulsification and formation of smaller particles (Abdelbary and Fahmy, 2009). Furthermore, the differences in hydrophilicity of both surfactants (Sznitowska, Wolska, Baranska, Cal, & Pietkiewicz, 2017) causes brij58 nanoparticles (HLB =15.7) to be significantly smaller (p < 0.0001) when compared

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to tego care 450 (HLB= 12) particles. The incorporation of 40% Labrafac lipophileWL1349 significantly decreased PS (p < 0.0001). This might indicate better emulsification due to decreasing the viscosity of the melted droplets (Elnaggar, El-Massik, & Abdallah, 2011). 3.1.2. EE% and DL The EE% and DL of all nanoparticles are shown in Table 3. The DL was found directly proportional to EE%. The ANOVA results illustrated in Fig. 1b shows that cetyl palmitate significantly (p<0.05) increased EE% when compared to Geleol due to its higher lipophilicity (Shah and Agrawal, 2013) which resulted in increased accommodation of AND which is a lipophilic drug (log P=2.9) (Baek, Shin, & Cho, 2012, Levita, Nawawi, Abdul Mutalib & Ibrahim, 2010). Also, Brij 58 gave significantly (p<0.05) higher EE% than tego care 450. This is in agreement with Tavano, De Cindio, Picci, Ioele, & Muzzalupo (2014) who stated that EE% is directly proportional to the HLB value of the surfactant. In addition, the incorporation of 40% liquid lipid significantly (p<0.05) increased the EE% due to the decrease of the perfect structure of the solid lipid with a subsequent increase of imperfections, hence leading to the formation of a not crystalline lipid blend and consequently the presence of free spaces existing for the incorporation of higher amount of drug molecules (Shah et al., 2016). 3.1.3. In vitro release

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(A)

(B)

12

(C) Fig. 2: In vitro release profile of AND from AND-nanoparticle formulations and AND suspension in PBS (pH 7.4) (A), Correlation between mean particle size and cumulative % AND released after 48 h (Q48) for nanoparticle formulations (B) and Transmission electron micrographs of the optimized AND-loaded nanostructured lipid carrier (C).

The prepared nanoparticles improved the release of AND over drug suspension in a controlled manner up to 48 h (Fig. 2 a). This is probably correlated to the solubilizing effect of the surfactants (Brij 58 and tego care 450) and the smaller PS (larger surface area) which enhanced the dissolution rate of AND lipid nanoparticles (Shamma and Aburahma, 2014). In vitro AND release from all nanoparticles exhibited biphasic release pattern with a low initial burst release up to 22.46% within 1h, due to minor AND density at the surface of the formulated nanoparticles (Jiang et al., 2014). Later, a controlled release manner was observed due to the slow liberation of AND imbedded in the lipid matrix. This profile enables the use of AND-naoparticles as a promising vector in wound healing (Mohandas, Anisha, Chennazhi, & Jayakumar, 2015a). An initial release is sufficient to allow the existence of drug at the wound site in a short period of time, whereas further steady release offers the drug over an extended period of time (Chereddy, Vandermeulen, & Préat, 2016).

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Furthermore, there is a negative correlation (r2= -0.892) between PS and Q48 (Fig. 2b). As larger nanoparticles make more total inner space for AND to be accommodated (Elsayed, Abdelbary, & Elshafeey, 2014). Moreover, release kinetic studies revealed that the release of AND from nanoparticles fitted a sustained-release first-order model, the mechanism for which might be explained by the fact that the drug incorporated into the solid-liquid lipid matrix was released in a sustained manner (Zhang et al., 2013). 3.2. Optimization of AND-lipid nanoparticles The optimized NLC4 composed of Geleol, 2% w/w Brij 58 and 40% w/w Labrafaclipophile WL1349 had the highest desirability value (0.882) and therefore, it was chosen as an optimal formulation. As depicted in Table 3, NLC4 showed a particle size of approximately 253 nm, 83.04% EE and 100 % AND was released after 48h. 3.3. Morphology of the optimized AND-nanoparticles The optimized formula NLC4 appears as deformed hexagonal-shaped particles (Fig.2c) it is viewed from a top view (Esposito, Drechsler, & Cortesi, 2013). The mean size of NLC4 appeared in TEM was clearly smaller than that measured by Dynamic light scattering. As during TEM sample preparation, nanoparticles become dehydrated; therefore their morphological size in the solid state was revealed. Whereas particle size analyzer measures hydrodynamic diameter (apparent size) of NLC4, including hydrodynamic layers around these nanoparticles leading to overestimation of the nanoparticles size (Ghorab, Gardouh, &Gad, 2015). 3.4. Characterization of the prepared scaffold

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(A)

B (i)

B (ii)

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(C) Fig. 3: (A) FT-IR of Chitosan, HA and chitosan-HA scaffold, (B) SEM micrographs of (i) chitosan–HA scaffold (ii) chitosan–HA/NLC4 composite scaffold at magnification 400x and (C) TEM micrograph of chitosan–HA/NLC4 composite scaffold. 3.4.1. FT-IR spectra By inspecting the FT-IR spectrum of the prepared chitosan-HA scaffold sponge and comparing it with those of chitosan and HA (Fig. 3a ), a new peak at 1572 cm-1 could be observed due to the formation of NH3+ group after the complexation of chitosan with HA (Kim, Shin, Lee, Park, & Kim, 2004). 3.4.2. Morphology The surface morphology of chitosan–HA and chitosan–HA/NLC4 scaffolds was shown by SEM images (Fig. 3b (i) and 3b (ii) respectively). A highly porous interconnected structure can be seen with extra sheets like structures were shown in chitosan–HA scaffolds and irregular porous morphology while a highly porous structure with a uniform distribution of pores in the case of chitosan–HA/NLC4 scaffold. The removal of water from the NLC4 suspension incorporated into the scaffold by lyophilization generated the vacant spaces which contributed to the recognized

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large number of uniform pores (Florczyk et al., 2013). Fig. (3c) depicted the distribution of NLC4 in the prepared scaffold and its integrity which indicated that the preparation process had no significant effect on the incorporated nanoparticle (Hazzah, Farid, Nasra, EL-Massik, & Abdallah, 2015). 3.4.3. Porosity

(A)

(B)

17

(C)

(D) Fig. 4: (A) Porosity% of chitosan–HA composite scaffold and Chitosan–HA/NLC4 composite scaffold and (B) swelling ratios in PBS (pH 7.4) of composite scaffolds and (C) In vitro release of AND from chitosan–HA/NLC4 composite scaffold and NLC4 in PBS (pH 7.4). (D) Antioxidant activity of chitosan–HA and chitosan–HA/NLC4 composite scaffolds. Porosity of a scaffold determines how well the material can transport nutrients and oxygen or absorb wound exudates. The fluid absorption would be cooperative in controlling infection at the wound site (Mohandas, Sudheesh Kumar, Raja, Lakshmanan, & Jayakumar, 2015b). These properties cause an improvement in cell respiration rate, skin regeneration, exudates removal and hemostasis (Rath, Hussain, Chauhan, Garg, & Goyal, 2016). Chitosan–HA/NLC4 scaffold showed improved porosity with respect to chitosan–HA scaffold (Fig. 4a) due to the incorporation of 18

nanoparticle in the suspension form, consequently, lyophilization would yield a highly porous structure (Anisha et al., 2013b). 3.4.4. Swelling behavior Fig. 4b showed that the degree of swelling of chitosan–HA scaffold is higher than that of chitosan–HA/NLC4 scaffold. This observation can be explained based on the effect of NLCs components. In this respect, the system might reveal the following possible interactions: hydrogen bonding between the hydroxyl and carbonyl groups present in Brij 58 (Polyoxyethylene 20 cetyl ether) and the ammonium ions and hydroxyl groups of the chitosan, in addition to hydrophobic interactions between Brij 58 tail and chitosan hydrophobic sites (Grant, Lee, Liu, & Allen, 2008).). Therefore, the presence of NLC is hypothesized to interfere with polymer swelling ability. Furthermore, Studies showed an increase in swelling ratio with time till 4 th day which decreased on the 7th day. Similar results were obtained by Anisha, Biswas, Chennazhi, & Jayakumar (2013a) and Anisha et al. (2013b). 3.4.5. In vitro release of AND from scaffold In vitro release results (Fig 4c) showed that incorporation of NLC4 into a chitosan-HA scaffold decreased the amount of AND release compared to that from NLC4 dispersion. Upon scaffold hydration, the polymers regain their gel structure leading to increase in diffusional path length of the drug release. Furthermore, the thick gel layer formed on the swollen scaffold surface is capable of preventing matrix disintegration and controlling additional water penetration hence retarding the drug release (Hazzah, Farid, Nasra, EL-Massik, & Abdallah, 2015). 3.4.6. Antioxidant activity measurements DPPH scavenging activity of the non-medicated scaffold was significantly lower than that of the medicated scaffold (p< 0.05) (Fig. 4d). These results indicates that chitosan-HA possess antioxidant activity which subsequently improved by the addition of AND. Various experimental models previously demonstrated the antioxidant activity of chitosan (López-Mata et al., 2015).),

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HA (Sato et al., 1988) and AND (Karmegam, Nagaraj, Karuppusamy, & Prakash, 2015). The antioxidant properties of chitosan-HA/NLC4 which play a significant role in protecting the tissues from oxidative damage could contribute to the healing process (Al-Bayaty, Abdulla, Abu Hassan, & Ali, 2012). 4.4.7. In vivo wound healing

(A)

(B)

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(C) Fig. 5: (A) Photographs of treated wounds at different time intervals (B) the wounds closure rate (a+: significant difference from control group (untreated) at the same time interval at p< 0.05, b+: significant difference from chitosan-HA scaffold group at the same time interval at p< 0.05. (C) Photomicrographs (H&E stain) of normal skin (i), burned skin at day 1 postwounding (ii), untreated control burned skin at day 21 post-wounding (iii), burned skin treated with chitosan-HA scaffold at day 21 post-wounding (iv) and burned skin treated with chitosan-HA/NLC4 scaffold at day 21 post-wounding (v) The wound healing results on day 1, 4, 12 and 21 are presented in Fig. 5 a. All the wounds showed progressive healing up to 21 days. The wounds treated with chitosan–HA/NLC4 scaffold healed faster than chitosan–HA scaffold treated groups and control. Fig. 5b shows the wound closure rate of the chitosan–HA/NLC4, chitosan–HA scaffolds and control groups. On the 4th day, reductions in wound area began in all wounds. On the 4 th and 12th days, the wound closure rates in the group treated with chitosan–HA/NLC4 scaffold was faster than those of chitosan–HA scaffold treated and control groups. On day 21, the wounds treated with the chitosan–HA/NLC4 scaffold had healed completely with no scar and improved tissue quality, whereas in chitosan–HA scaffold and control groups the wound closure rates are 95.3 % and 85.3 % respectively. This indicates that chitosan–HA/NLC4 scaffolds were effective and beneficial for accelerated and healthy wound healing.This positive healing effect might be due to the combined anti21

inflammatory and antioxidant effect of AND (Li et al., 2016) that is slowly released from the optimized NLC4 together with the effect of chitosan and HA. AND as one of the main components of Andrographis paniculata extract that has been reported to accelerate the wound healing process (Al-Bayaty, Abdulla, Abu Hassan& Ali, 2012). In addition, it was stated (Archana et al., 2013) that throughout the process of wound healing, depolymerization of chitosan gradually took place to release N-acetylglucosamine, which helps in the deposition of ordered collagen and initiates fibroblast proliferation and stimulates the synthesis of a high level of natural HA at the wound site. Besides, HA is known to have high potential for scar reduction. Also, the incorporation of NLC4 in such scaffold increases the probability of its dermal localization and subsequently improving its efficacy (El-Refaie, Elnaggar, El-Massik,& Abdallah, 2015). 3.4.8. Histological observation At the 21st day study, the control showed a complete loss of keratin layer as well as details of the prickle cells layer in the epidermis, fibrosis and few newly formed granulation tissue in the dermis. The subcutaneous tissue showed edema with few inflammatory cells infiltration while the musculature was intact (Fig.5c (iii)). On the other hand, wounds treated with chitosan-HA scaffold showed fine keratin layer with underlying ill-defined prickle cell layer of the epidermis as well as wide granulation tissue formation in the dermis. The subcutaneous tissue and musculature were intact (Fig.5c (iv)). The wound treated with chitosan-HA/NLC4 scaffold indicate intact keratin layer with underlying defined prickle cell layer of the epidermis as well as granulation tissue formation in the dermis. The subcutaneous and musculature tissues were intact as shown in Fig.5c (iv). The presence of hair follicles and matured fibrous tissues confirmed efficient healing. This can easily be compiled with a statement that it provides the moist environment at the wound site,which speeds up various stages of wound healing especially epithelialization (Jin et al., 2015).

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These results are in line with what detected by Al-Bayaty, Abdulla, Abu Hassan, & Ali, (2012) who observed that histologically, wounds dressed with Andrographis paniculata extract (its main bioactive component is AND) contained high amounts of fibroblast proliferation. 4. Conclusion In this study, AND-nanoparticles were developed and optimized. The optimized lipid nanoparticle formulation was then successfully incorporated into a chitosan-HA scaffold. The developed chitosan–HA/NLC4 scaffold showed appropriate porosity, swelling ratio controlled drug release up to 72 has well as superior wound healing, reduced scar formation and improved histological progress when compared to control. This was attributed to the combined antiinflammatory and antioxidant effect of chitosan and HA together with the effect of AND. In conclusion this chitosan–HA/NLC4 scaffold would be a potential candidate for wound healing applications. Conflict of interest The authors report no financial or personal conflict of interest. 

Abbreviation list: AND: Andrographolide. HA: Hyaluronic acid SLNs: Solid lipid nanoparticles. NLCs: Nanostructured lipid carriers. PS: Particle size. PDI: Polydispersity index. EE%: Entrapment efficiency percent. DL: Drug loading capacity. Q48: % andrographolide released after 48 h. UPLC: Ultra Performance Liquid Chromatography. PBS: Phosphate buffered saline. TEM: Transmission electron microscope. SEM: Scanning electron microscope. DPPH: 2, 2-diphenyl- 1-picrylhydrazyl. AA%: The DPPH scavenged activity percentage. Log P: Octanol-water partition coefficient. 23

HLB: Hydrophilic lipophilic balance.

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Fig. 1: 3D response plots for the effect of solid lipid type (X1), surfactant type (X2) and liquid lipid concentration (X3) on the PS (A), EE% (B) and cumulative release after 48 h (Q48) (C) of AND-nanoparticle formulations.

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Table 1 Experimental runs and independent variables of full factorial design for nanoparticle formulations X2: Surfactant type.

X3: Labrafac conc*.

Formulation

X1: Solid lipid

code

type.

SLN1

Cetyl palmitate

Tego care 450

0

SLN2

Cetyl palmitate

Brij 58

0

SLN3

Geleol

Tego care 450

0

SLN4

Geleol

Brij 58

0

NLC1

Cetyl palmitate

Tego care 450

40

NLC2

Cetyl palmitate

Brij 58

40

NLC3

Geleol

Tego care 450

40

NLC4

Geleol

Brij 58

40

(%)

Table 2: Full factorial design used for optimization of nanoparticle formulations Factors (independent variables)

Levels

X1: solid lipid type

Cetyl palmitate

Geleol

X2: surfactant type

Tegocare 450

Brij 58

X3: Labrafac lipophileWL1349 concentration

0%

40%

Responses (dependent variables)

Desirability constraints

Y1: PS (nm)

Minimize

Y2: EE%

Maximize

Y3: Q 48 h (%)

Maximize

Table 3: The measured responses of full factorial design for nanoparticle formulations: Formulation

Y1: PS (nm)

Y2: %EE

Y3: %AND released

code

PDI*

after 48 h

Drug loading capacity*

SLN1

465±4.20

75.75±6.42

50.56±4.29

0.86

21.65

SLN2

348.5±7.70

75.66±6.41

71.00±6.02

0.91

21.64

31

SLN3

322±2.80

58.18±4.93

92.84±7.87

0.55

16.61

SLN4

343±8.48

69.49±4.20

100.00±9.89

0.73

19.85

NLC1

438±11.3

80.15±6.80

68.31±6.76

0.84

22.91

NLC2

297±11.3

87.36±7.41

98.64±11.16

0.90

24.96

NLC3

288±9.89

70.50±3.43

98.83±12.57

0.48

20.14

NLC4

253±16.97

83.04±7.04

100.00±7.07

0.53

23.72

32