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chitosan complex coatings with superior osteoblastic cell response
Materials Letters 65 (2011) 974–977
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Antibacterial hydroxyapatite/chitosan complex coatings with superior osteoblastic cell response Lei Song, Lu Gan, Yan-Feng Xiao, Yao Wu, Fang Wu ⁎, Zhong-Wei Gu National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610064, P.R. China
a r t i c l e
i n f o
Article history: Received 3 October 2010 Accepted 25 December 2010 Available online 31 December 2010 Keywords: Bioceramics Porous materials Antibacterial materials Chitosan Hydroxyapatite coating Liquid precursor plasma spraying
a b s t r a c t Chitosan was widely used as an antibacterial component. While most antibacterial materials also possess cytotoxicities, we hypothesize that selectively destruction of bacterial cells can be achieved by controlling the material parameters of chitosan, due to its intrinsic antibacterial mechanism. In this study, porous hydroxyapatite coatings prepared by the liquid precursor plasma spraying process were used for loading the chitosan with different concentrations: 10, 20, 50, and 100 g/L, respectively. The antibacterial properties and osteoblastic cell response of the hydroxyapatite/chitosan complex coatings were studied as a function of chitosan concentration. The results indicated that the antimicrobial activity was directly proportional to the chitosan concentration, while loading of chitosan with lower concentrations (10 and 20 g/L) was even beneficial to the proliferation of osteoblastic cells. Overall, our study demonstrated that combined antibacterial activity and superior osteoblast cell response can be achieved by using hydroxyapatite/chitosan complex coatings, which have great potential in bone replacement and regeneration applications. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Plasma sprayed hydroxyapatite coatings applied on Ti-6Al-4 V substrates have been widely used in joint prosthesis and dentistry applications, owing to the combination of the excellent mechanical properties of Ti alloys and the favorable osteoconductive and bioactive properties of the HA coatings [1–3]. However, due to the favorable bioactive property and the proper body nutrition and temperature, they are usually in favor of the bacteria adherence and colonization on the implant, which cause the failure of the implant [4]. Therefore, antibacterial materials have been added into the HA coating to effectively reduce the postoperative infection. However, the addition of antimicrobial materials would generally lead to cytotoxicity and be detrimental for bone formation and growth, while bone ingrowth at early stage is critical for implant/bone fixation and patient recuperation. Among all the antibacterial materials, chitosan is a widely used natural polymer, generated by deacetylation of chitin, with combined biodegradability, non-toxicity, antibacterial and hemostasis properties [5]. The combination of chitosan and HA has drawn much attention in antimicrobial applications [6]. The intrinsic antibacterial activity of chitosan lies in the interference of its cationic amino group with the negatively charged residues of macromolecules at the surface of bacterial wall, which affects the permeability of the bacterial membrane [7]. However, its electrostatic interaction with anionic
⁎ Corresponding author. Tel.: +86 28 85412923; fax: +86 28 85412848. E-mail addresses: [email protected], [email protected] (F. Wu). 0167-577X/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2010.12.051
glycosaminoglycans (GAG) and other negatively charged molecules would also likely promote the adhesion of osteoblast cells. Moreover, due to its cationic nature and predictable degradation rate, chitosan based materials are also suitable to bind growth factors and release them in a controlled fashion [8]. Therefore, it is logical to hypothesize that dual function of chitosan (antibacterial activity and promotion of osteoblast cell proliferation) may be achieved through the selective destruction of the bacterial cell, since bacteria and osteoblastic cells vary significantly in their size and properties. This article is intended to test whether antimicrobial activity and enhanced osteoblastic cell response can be simultaneously achieved by using the HA/chitosan complex coatings. In addition, to promote the loading of chitosan, porous HA coatings synthesized by a novel liquid precursor plasma spraying (LPPS) process [9,10] were used as the coating materials. This process allows us to deposit porous HA coatings with reasonably good adhesion and controllable microstructure (from nearly fully dense to highly porous structure) [10]. 2. Materials and methods 2.1. Preparation and characterization of porous HA coating Ti-6Al-4 V disks with 14 mm diameter and 1.5 mm thickness were used as the substrates. The substrate surface was grit-blasted with alumina abrasives (380 μm particle size, 0.4–0.7 MPa grit-blast pressure) prior to the plasma spraying and ultrasonically cleaned in acetone and ethanol. Porous HA coatings were deposited onto the Ti alloy substrates with Metco MN air plasma spraying system (Metco
L. Song et al. / Materials Letters 65 (2011) 974–977
975
Ltd., USA) and an AR2000 thermal spraying robot. The liquid HA precursors, prepared through a wet-chemical route [11], were transported through a peristaltic pump and injected into the plasma flume through an atomizing nozzle (Bete Inc). Nitrogen and Hydrogen were used as the primary gas and the secondary gas, respectively. The thicknesses of the HA coatings were at around 100 μm. More detailed information of the LPPS process and spraying parameters can be found elsewhere [9,10]. The surface morphologies of the coatings were examined by the scanning electron microscope (Hitachi S-4800). 2.2. Loading of chitosan with different concentration The chitosan (N-carboxymethyl chitosan; MW = 3 × 104; degree of deacetylation: 85%, Aoxing Biotech, Zhejiang, China) was dissolved in ultrapure water with concentrations of 10, 20, 50 and 100 g/L, respectively. The HA-coated Ti-6Al-4 V samples were immersed into the chitosan solutions for 24 h in sterilized condition. Afterwards, the samples were kept in a laminar flow cabinet for air drying. The pure HA coatings without any addition of chitosan were used as control. 2.3. Bacteria inhibition Staphylococcus aureus (ATCC 25923) was used for testing the antibacterial properties of the HA/chitosan complex coatings in this study. A suspension of S. aureus bacteria with concentration of 1 ~ 2 × 106 CFUs/mL was added to 24-well plates, and cultured for 6 h, 12 h and 24 h, respectively. MTT assay was selected to investigate the bacterial inhibition behavior. Optical density (OD) was detected at 490 nm and the proliferation of S. aureus was determined by the OD value. SEM was used to analyze the bacteria adhesion on the coating surface, after 24 h culture time.
Fig. 1. SEM micrographs of the porous HA coating surface: (a) as-deposited; (b) after loading of chitosan.
2.4. Cytotoxicity on osteoblastic cell Suspension of MG63 cells with number of 1 × 104 per milliliter was added to 24-well plates, and cultured for 2, 4 and 6 days, respectively. MTT assay was selected and the OD values at 570 nm were measured. 3. Results and discussion 3.1. Porous HA coatings synthesized by the LPPS process As described before, porous HA coatings were synthesized by the LPPS process, to achieve a better loading of chitosan. Fig. 1 shows the morphology of the HA coating surface before and after chitosan infiltration. A well porous structure is observed, with pore size ranging from 10 to 100 μm for the as-deposited HA coatings (Fig. 1a). After chitosan loading, it appeared that the chitosan had infiltrated into the pores and the coatings were completely covered by the chitosan (Fig. 1b). The increased specific surface area of porous coating is beneficial to the adsorption of polymer materials and a more sustainable release of antibacterial materials. Porous structure might also lead to a high local concentration of antibacterial materials and enhanced antibacterial activity.
significant growth of bacteria has been observed for coating loaded with 10 g/L chitosan. 3.3. Surface morphology of S. aureus cultured on the coating surfaces The SEM micrographs of S. aureus cultured on the different coating specimens were shown in Fig. 3. After being cultured for 24 h, the S. aureus on the control surface gathered together to form big clusters, suggesting favorable conditions for the growth of S. aureus on the untreated HA coatings. The bacteria had a scattered distribution on the surfaces of coating loaded with 10 g/L chitosan, with significant reduction in number. As the chitosan concentration increased to 100 g/L, almost no S. aureus was observed on the coating surface. 3.4. Osteoblastic cell response of HA/chitosan complex coatings In order to evaluate the cell toxicity, MTT method was used to measure the proliferation of MG63 cells on the coating surfaces. Fig. 4
3.2. Antibacterial activities of HA/chitosan complex coatings Fig. 2 shows the OD values of S. aureus for different coating samples as a function of culture time. No significant difference was found between the HA/chitosan complex coatings and the control at 6 h. At 12 h, porous HA/chitosan complex coatings with four different concentrations all demonstrated significant antibacterial activity, while significant bacterial growth was observed for the control. At 24 h, the antibacterial properties of the HA/chitosan complex coatings showed distinct difference. While the HA coatings loaded with 20, 50 and 100 g/L chitosan still possess obvious antibacterial properties,
Fig. 2. MTT result of S. aureus cultured on the HA/chitosan coatings for 6 h, 12 h and 24 h, respectively.
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L. Song et al. / Materials Letters 65 (2011) 974–977
control. This is not surprising since the intrinsic antibacterial property of chitosan is also expected to have an adverse effect on the osteoblatsic cell viability. However, it is interesting to see that the cell growth on coatings loaded with 10 and 20 g/L chitosan was not only significantly higher than those on coatings loaded with 50 and 100 g/L chitosan, but also significantly higher than that on the control, the pure HA coating without loading of chitosan. The results indicate that the loading of chitosan is even beneficial for the proliferation of osteoblastic cell at low concentrations. This could be explained by the antibacterial mechanism of chitosan. It mainly relies on its positive charge to attract and break the negatively charged bacterial cell wall, which would also work adversely on the osteoblastic cells. However, at certain concentration and contact time, the negatively charged osteoblastic cells may be just attracted to the HA/chitosan coating surface without undergoing further impairment, which leads to enhanced cell adhesion and proliferation. In addition, the electrostatic interaction of chitosan with the negatively charged molecules would also likely help the adsorption of certain proteins, which would promote the adhesion of the osteoblast cells. Therefore, a window of concentration was found in our experiments, where chitosan can selectively do harm to the bacteria, but not the osteoblastic cells. While numerous reports can be found in the literature regarding either the antibacterial effect [12] or the enhancement of osteoblastic cell proliferation [13] of chitosan, this is the first report on the observation of “dual” function of chitosan, as we know so far. It also appears that chitosan sticks very well to the HA coating surface, even during the in-vitro tests. Our results indicate that by tuning the chitosan concentration, combined antibacterial activity and enhanced osteoblast function can be achieved simultaneously in the porous-HA/chitosan complex coatings. However, the window for selective destruction of bacteria may also depend on other factors such as dosage, contact time, and degree of deacetylation (DD) [14], molecular weight of chitosan, and so on. Therefore, the physical and chemical properties of the chitosan can be controlled and optimized to allow the coexistence of antibacterial activity and enhanced osteoblastic cell response. 4. Conclusions
Fig. 3. SEM photographs of S. aureus cultured on the coatings for 24 h: (a) blank control; (b) 10 g/L chitosan; (c) 100 g/L chitosan.
shows the proliferation results of cells cultured for 2, 4, and 6 days, respectively. For all times, the OD values of HA coatings loaded with 50 and 100 g/L chitosan were significant lower than that of the
In this study, chitosan with different concentrations were successfully incorporated into the porous HA coatings and their antibacterial properties and osteoblast cell cytotoxicity were studied. The results indicated that the antibacterial efficacy on S. aureus increases proportionately with the increase of chitosan concentration. However, coating with low chitosan concentrations (10 and 20 g/L) also exhibited enhanced proliferation of osteoblast cells, indicating a concentration window for selective destruction of bacteria. Overall, our results suggest that the usage of porous-hydroxyapatite/chitosan complex coatings can simultaneously achieve superior antibacterial activity and enhanced osteoblast cell response, which have great potential in orthopedic applications. Acknowledgement The present research was supported by the National High Technology Research and Development Program (863 Program) of P.R. China (No. 2006AA02A135) and Sichuan Youth Science and Technology Foundation of P.R. China (No. 08ZQ026-022). References [1] [2] [3] [4]
Fig. 4. MTT result of MG63 cultured on the HA/chitosan coatings after 2, 4 and 6 days, respectively.
Chen C, Huang T, Kao C, Ding S. J Biomed Mater Res B 2006;78:146–52. Lu Y, Xiao G, Li S, Sun R, Li M. Appl Surf Sci 2006;252:2412–21. Sun L, Berndt C, Khor K, Cheang H, Gross K. J Biomed Mate Res A 2002;62:228–36. Hendriks J, Van Horn J, Van Der Mei H, Busscher H. Biomaterials 2004;25: 545–56. [5] Chung Y, Chen C. Bioresour Technol 2008;99:2806–14.
L. Song et al. / Materials Letters 65 (2011) 974–977 [6] [7] [8] [9]
Boccaccini A, Roether J, Zhitomirsky I. J Mater Proc Technol 2009;209:1853–60. Sudarshan N, Hoover D, Knorr D. Food Biotechnol 1992;6:257–72. Di Martino A, Sittinger M, Risbud M. Biomaterials 2005;26:5983–90. Huang Y, Song L, Huang T, Liu XG, Xiao YF, Wu Y, et al. Biomed Mate 2010;5: 054113. [10] Huang Y, Song L, Liu XG, Xiao YF, Wu F, Wu Y, et al. Biofabrication 2010;2:045003.
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[11] Pretto M, Costa A, Landi E, Tampieri A, Galassi C. J Am Ceram Soc 2003;86:1534–9. [12] Liu N, Chen XG, Park HJ. Carbohydr Polym 2006;64(1):60–5. [13] Seol YJ, Lee JY, Park YJ, Lee YM, Young-Ku, Rhyu IC, et al. Biotechnol Lett 2004;26: 1037–41. [14] Liu N, Chen X, Park H, Liu C, Liu C, Meng X, et al. Carbohyd Polym 2006;64:60–5.
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Antibacterial hydroxyapatite/chitosan complex coatings with superior osteoblastic cell response Lei Song, Lu Gan, Yan-Feng Xiao, Yao Wu, Fang Wu ⁎, Zhong-Wei Gu National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610064, P.R. China
a r t i c l e
i n f o
Article history: Received 3 October 2010 Accepted 25 December 2010 Available online 31 December 2010 Keywords: Bioceramics Porous materials Antibacterial materials Chitosan Hydroxyapatite coating Liquid precursor plasma spraying
a b s t r a c t Chitosan was widely used as an antibacterial component. While most antibacterial materials also possess cytotoxicities, we hypothesize that selectively destruction of bacterial cells can be achieved by controlling the material parameters of chitosan, due to its intrinsic antibacterial mechanism. In this study, porous hydroxyapatite coatings prepared by the liquid precursor plasma spraying process were used for loading the chitosan with different concentrations: 10, 20, 50, and 100 g/L, respectively. The antibacterial properties and osteoblastic cell response of the hydroxyapatite/chitosan complex coatings were studied as a function of chitosan concentration. The results indicated that the antimicrobial activity was directly proportional to the chitosan concentration, while loading of chitosan with lower concentrations (10 and 20 g/L) was even beneficial to the proliferation of osteoblastic cells. Overall, our study demonstrated that combined antibacterial activity and superior osteoblast cell response can be achieved by using hydroxyapatite/chitosan complex coatings, which have great potential in bone replacement and regeneration applications. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Plasma sprayed hydroxyapatite coatings applied on Ti-6Al-4 V substrates have been widely used in joint prosthesis and dentistry applications, owing to the combination of the excellent mechanical properties of Ti alloys and the favorable osteoconductive and bioactive properties of the HA coatings [1–3]. However, due to the favorable bioactive property and the proper body nutrition and temperature, they are usually in favor of the bacteria adherence and colonization on the implant, which cause the failure of the implant [4]. Therefore, antibacterial materials have been added into the HA coating to effectively reduce the postoperative infection. However, the addition of antimicrobial materials would generally lead to cytotoxicity and be detrimental for bone formation and growth, while bone ingrowth at early stage is critical for implant/bone fixation and patient recuperation. Among all the antibacterial materials, chitosan is a widely used natural polymer, generated by deacetylation of chitin, with combined biodegradability, non-toxicity, antibacterial and hemostasis properties [5]. The combination of chitosan and HA has drawn much attention in antimicrobial applications [6]. The intrinsic antibacterial activity of chitosan lies in the interference of its cationic amino group with the negatively charged residues of macromolecules at the surface of bacterial wall, which affects the permeability of the bacterial membrane [7]. However, its electrostatic interaction with anionic
⁎ Corresponding author. Tel.: +86 28 85412923; fax: +86 28 85412848. E-mail addresses: [email protected], [email protected] (F. Wu). 0167-577X/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2010.12.051
glycosaminoglycans (GAG) and other negatively charged molecules would also likely promote the adhesion of osteoblast cells. Moreover, due to its cationic nature and predictable degradation rate, chitosan based materials are also suitable to bind growth factors and release them in a controlled fashion [8]. Therefore, it is logical to hypothesize that dual function of chitosan (antibacterial activity and promotion of osteoblast cell proliferation) may be achieved through the selective destruction of the bacterial cell, since bacteria and osteoblastic cells vary significantly in their size and properties. This article is intended to test whether antimicrobial activity and enhanced osteoblastic cell response can be simultaneously achieved by using the HA/chitosan complex coatings. In addition, to promote the loading of chitosan, porous HA coatings synthesized by a novel liquid precursor plasma spraying (LPPS) process [9,10] were used as the coating materials. This process allows us to deposit porous HA coatings with reasonably good adhesion and controllable microstructure (from nearly fully dense to highly porous structure) [10]. 2. Materials and methods 2.1. Preparation and characterization of porous HA coating Ti-6Al-4 V disks with 14 mm diameter and 1.5 mm thickness were used as the substrates. The substrate surface was grit-blasted with alumina abrasives (380 μm particle size, 0.4–0.7 MPa grit-blast pressure) prior to the plasma spraying and ultrasonically cleaned in acetone and ethanol. Porous HA coatings were deposited onto the Ti alloy substrates with Metco MN air plasma spraying system (Metco
L. Song et al. / Materials Letters 65 (2011) 974–977
975
Ltd., USA) and an AR2000 thermal spraying robot. The liquid HA precursors, prepared through a wet-chemical route [11], were transported through a peristaltic pump and injected into the plasma flume through an atomizing nozzle (Bete Inc). Nitrogen and Hydrogen were used as the primary gas and the secondary gas, respectively. The thicknesses of the HA coatings were at around 100 μm. More detailed information of the LPPS process and spraying parameters can be found elsewhere [9,10]. The surface morphologies of the coatings were examined by the scanning electron microscope (Hitachi S-4800). 2.2. Loading of chitosan with different concentration The chitosan (N-carboxymethyl chitosan; MW = 3 × 104; degree of deacetylation: 85%, Aoxing Biotech, Zhejiang, China) was dissolved in ultrapure water with concentrations of 10, 20, 50 and 100 g/L, respectively. The HA-coated Ti-6Al-4 V samples were immersed into the chitosan solutions for 24 h in sterilized condition. Afterwards, the samples were kept in a laminar flow cabinet for air drying. The pure HA coatings without any addition of chitosan were used as control. 2.3. Bacteria inhibition Staphylococcus aureus (ATCC 25923) was used for testing the antibacterial properties of the HA/chitosan complex coatings in this study. A suspension of S. aureus bacteria with concentration of 1 ~ 2 × 106 CFUs/mL was added to 24-well plates, and cultured for 6 h, 12 h and 24 h, respectively. MTT assay was selected to investigate the bacterial inhibition behavior. Optical density (OD) was detected at 490 nm and the proliferation of S. aureus was determined by the OD value. SEM was used to analyze the bacteria adhesion on the coating surface, after 24 h culture time.
Fig. 1. SEM micrographs of the porous HA coating surface: (a) as-deposited; (b) after loading of chitosan.
2.4. Cytotoxicity on osteoblastic cell Suspension of MG63 cells with number of 1 × 104 per milliliter was added to 24-well plates, and cultured for 2, 4 and 6 days, respectively. MTT assay was selected and the OD values at 570 nm were measured. 3. Results and discussion 3.1. Porous HA coatings synthesized by the LPPS process As described before, porous HA coatings were synthesized by the LPPS process, to achieve a better loading of chitosan. Fig. 1 shows the morphology of the HA coating surface before and after chitosan infiltration. A well porous structure is observed, with pore size ranging from 10 to 100 μm for the as-deposited HA coatings (Fig. 1a). After chitosan loading, it appeared that the chitosan had infiltrated into the pores and the coatings were completely covered by the chitosan (Fig. 1b). The increased specific surface area of porous coating is beneficial to the adsorption of polymer materials and a more sustainable release of antibacterial materials. Porous structure might also lead to a high local concentration of antibacterial materials and enhanced antibacterial activity.
significant growth of bacteria has been observed for coating loaded with 10 g/L chitosan. 3.3. Surface morphology of S. aureus cultured on the coating surfaces The SEM micrographs of S. aureus cultured on the different coating specimens were shown in Fig. 3. After being cultured for 24 h, the S. aureus on the control surface gathered together to form big clusters, suggesting favorable conditions for the growth of S. aureus on the untreated HA coatings. The bacteria had a scattered distribution on the surfaces of coating loaded with 10 g/L chitosan, with significant reduction in number. As the chitosan concentration increased to 100 g/L, almost no S. aureus was observed on the coating surface. 3.4. Osteoblastic cell response of HA/chitosan complex coatings In order to evaluate the cell toxicity, MTT method was used to measure the proliferation of MG63 cells on the coating surfaces. Fig. 4
3.2. Antibacterial activities of HA/chitosan complex coatings Fig. 2 shows the OD values of S. aureus for different coating samples as a function of culture time. No significant difference was found between the HA/chitosan complex coatings and the control at 6 h. At 12 h, porous HA/chitosan complex coatings with four different concentrations all demonstrated significant antibacterial activity, while significant bacterial growth was observed for the control. At 24 h, the antibacterial properties of the HA/chitosan complex coatings showed distinct difference. While the HA coatings loaded with 20, 50 and 100 g/L chitosan still possess obvious antibacterial properties,
Fig. 2. MTT result of S. aureus cultured on the HA/chitosan coatings for 6 h, 12 h and 24 h, respectively.
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L. Song et al. / Materials Letters 65 (2011) 974–977
control. This is not surprising since the intrinsic antibacterial property of chitosan is also expected to have an adverse effect on the osteoblatsic cell viability. However, it is interesting to see that the cell growth on coatings loaded with 10 and 20 g/L chitosan was not only significantly higher than those on coatings loaded with 50 and 100 g/L chitosan, but also significantly higher than that on the control, the pure HA coating without loading of chitosan. The results indicate that the loading of chitosan is even beneficial for the proliferation of osteoblastic cell at low concentrations. This could be explained by the antibacterial mechanism of chitosan. It mainly relies on its positive charge to attract and break the negatively charged bacterial cell wall, which would also work adversely on the osteoblastic cells. However, at certain concentration and contact time, the negatively charged osteoblastic cells may be just attracted to the HA/chitosan coating surface without undergoing further impairment, which leads to enhanced cell adhesion and proliferation. In addition, the electrostatic interaction of chitosan with the negatively charged molecules would also likely help the adsorption of certain proteins, which would promote the adhesion of the osteoblast cells. Therefore, a window of concentration was found in our experiments, where chitosan can selectively do harm to the bacteria, but not the osteoblastic cells. While numerous reports can be found in the literature regarding either the antibacterial effect [12] or the enhancement of osteoblastic cell proliferation [13] of chitosan, this is the first report on the observation of “dual” function of chitosan, as we know so far. It also appears that chitosan sticks very well to the HA coating surface, even during the in-vitro tests. Our results indicate that by tuning the chitosan concentration, combined antibacterial activity and enhanced osteoblast function can be achieved simultaneously in the porous-HA/chitosan complex coatings. However, the window for selective destruction of bacteria may also depend on other factors such as dosage, contact time, and degree of deacetylation (DD) [14], molecular weight of chitosan, and so on. Therefore, the physical and chemical properties of the chitosan can be controlled and optimized to allow the coexistence of antibacterial activity and enhanced osteoblastic cell response. 4. Conclusions
Fig. 3. SEM photographs of S. aureus cultured on the coatings for 24 h: (a) blank control; (b) 10 g/L chitosan; (c) 100 g/L chitosan.
shows the proliferation results of cells cultured for 2, 4, and 6 days, respectively. For all times, the OD values of HA coatings loaded with 50 and 100 g/L chitosan were significant lower than that of the
In this study, chitosan with different concentrations were successfully incorporated into the porous HA coatings and their antibacterial properties and osteoblast cell cytotoxicity were studied. The results indicated that the antibacterial efficacy on S. aureus increases proportionately with the increase of chitosan concentration. However, coating with low chitosan concentrations (10 and 20 g/L) also exhibited enhanced proliferation of osteoblast cells, indicating a concentration window for selective destruction of bacteria. Overall, our results suggest that the usage of porous-hydroxyapatite/chitosan complex coatings can simultaneously achieve superior antibacterial activity and enhanced osteoblast cell response, which have great potential in orthopedic applications. Acknowledgement The present research was supported by the National High Technology Research and Development Program (863 Program) of P.R. China (No. 2006AA02A135) and Sichuan Youth Science and Technology Foundation of P.R. China (No. 08ZQ026-022). References [1] [2] [3] [4]
Fig. 4. MTT result of MG63 cultured on the HA/chitosan coatings after 2, 4 and 6 days, respectively.
Chen C, Huang T, Kao C, Ding S. J Biomed Mater Res B 2006;78:146–52. Lu Y, Xiao G, Li S, Sun R, Li M. Appl Surf Sci 2006;252:2412–21. Sun L, Berndt C, Khor K, Cheang H, Gross K. J Biomed Mate Res A 2002;62:228–36. Hendriks J, Van Horn J, Van Der Mei H, Busscher H. Biomaterials 2004;25: 545–56. [5] Chung Y, Chen C. Bioresour Technol 2008;99:2806–14.
L. Song et al. / Materials Letters 65 (2011) 974–977 [6] [7] [8] [9]
Boccaccini A, Roether J, Zhitomirsky I. J Mater Proc Technol 2009;209:1853–60. Sudarshan N, Hoover D, Knorr D. Food Biotechnol 1992;6:257–72. Di Martino A, Sittinger M, Risbud M. Biomaterials 2005;26:5983–90. Huang Y, Song L, Huang T, Liu XG, Xiao YF, Wu Y, et al. Biomed Mate 2010;5: 054113. [10] Huang Y, Song L, Liu XG, Xiao YF, Wu F, Wu Y, et al. Biofabrication 2010;2:045003.
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[11] Pretto M, Costa A, Landi E, Tampieri A, Galassi C. J Am Ceram Soc 2003;86:1534–9. [12] Liu N, Chen XG, Park HJ. Carbohydr Polym 2006;64(1):60–5. [13] Seol YJ, Lee JY, Park YJ, Lee YM, Young-Ku, Rhyu IC, et al. Biotechnol Lett 2004;26: 1037–41. [14] Liu N, Chen X, Park H, Liu C, Liu C, Meng X, et al. Carbohyd Polym 2006;64:60–5.