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Chitosan, produced from chitin, is one of the polymers with promising applications in various fields. However, despite diverse research studies conducted on its biocompatibility, its uses are still limited. The main reason is the degree of deacetylation (DOD), which represents the proportion of deacetylated units in the polymer and is directly correlated with its biocompatibility property. In this article, the in vivo biocompatibility of three chitosan-hydroxyapatite composite films composed of chitosan with different DOD values was investigated by traditional biological protocols and novel optical spectroscopic analyses. The DOD of the chitosan obtained from three different manufacturers was estimated and calculated by Raman spectroscopy, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance spectroscopy. The chitosan with the higher DOD induced a higher incidence of inflammation in skin cells. The amino group density, biodegradability, and crystallinity of chitosan are the three possible factors that need to be considered when determining the biocompatibility of the films for in vivo application, as they led to complicated biological results, resulting in either better or worse inflammation even when using chitosan products with the same DOD. This basic study on the relationship between the DOD and inflammation is valuable for the development of further chitosan-based researches. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1637-1645, 2017., (© 2017 Wiley Periodicals, Inc.)

Background: Oregano essential oil (EO) was incorporated into film-forming dispersions (FFDs) based on biopolymers (chitosan and/or methylcellulose) at two different concentrations. The effect of the application of the FFDs was evaluated on tomato plants (cultivar Micro-Tom) at three different stages of development, and on pre-harvest and postharvest applications on tomato fruit., Results: The application of the FFDs at '3 Leaves' stage caused phytotoxic problems, which were lethal when the EO was applied without biopolymers. Even though plant growth and development were delayed, the total biomass and the crop yield were not affected by biopolymer-EO treatments. When the FFDs were applied in the 'Fruit' stage the pre-harvest application of FFDs had no negative effects. All FFDs containing EO significantly reduced the respiration rate of tomato fruit and diminished weight loss during storage. Moreover, biopolymer-EO FFDs led to a decrease in the fungal decay of tomato fruit inoculated with Rhizopus stolonifer spores, as compared with non-treated tomato fruit and those coated with FFDs without EO., Conclusion: The application of biopolymer-oregano essential oil coatings has been proven to be an effective treatment to control R. stolonifer in tomato fruit. © 2016 Society of Chemical Industry., (© 2016 Society of Chemical Industry.)

Chronic inflammatory responses after implantation of biomaterials can lead to fibrotic encapsulation and failure of implants. The present study was designed to reduce the inflammatory responses to biomaterials by assembling polyelectrolyte multilayers (PEMs) composed of glycosaminoglycans (GAGs) and chitosan (Chi) on glass as model surfaces through layer-by-layer (LBL) technique. Surface plasmon resonance (SPR) and water contact angle (WCA) investigations confirmed the multilayer build-up with alternating deposition of GAGs and Chi layers, while zeta potential measurements showed significant negative charges after multilayer deposition, which further proved the PEM formation. Macrophage adhesion, macrophage spreading morphology, foreign body giant cell (FBGC) formation, as well as β1 integrin expression and interleukin-1β (IL-1β) production were all significantly decreased by GAG-Chi multilayer deposition in comparison to the primary poly (ethylene imine) (PEI) layer. Thereby, the type of GAGs played a pivotal role in inhibiting the inflammatory responses to various extents. Especially heparin (Hep)-Chi multilayers hindered all inflammatory responses to a significantly higher extent in comparison to hyaluronic acid (HA)-Chi and chondroitin sulfate (CS)-Chi multilayer systems. Overall, the present study suggests a great potential of GAG-Chi multilayer coating on implants, particularly the Hep-Chi based systems, to reduce the inflammatory responses., (© 2015 Wiley Periodicals, Inc.)

Chitosan (CS) is widely used as a scaffold material in tissue engineering. The objective of this study was to test whether porous chitosan membrane (PCSM) coating for Nafion used in implantable sensor reduced fibrous capsule (FC) density and promoted superior vascularization compared with PCSM coating for polytetrafluoroethylene (PTFE). PCSM was fabricated with solvent casting/particulate leaching method using silica gel as porogen and characterized in vitro. Then, PCSM-Nafion and PCSM-PTFE composites were assembled with hydrated PCSM and implanted subcutaneously in rats. The histological analysis was performed in comparison with Nafion and PTFE. Implants were explanted 35, 65, and 100 days after the implantation. Histological assessments indicated that both composites achieved presumed effects of porous coatings on decreasing collagen deposition and promoting angiogenesis. PCSM-PTFE exerted higher collagen deposition by area ratio, both within and outside, compared with that of PCSM-Nafion. Angiogenesis within and outside the PCSM-Nafion both increased over time, but that of the PCSM-PTFE within decreased., (Copyright © 2013 Wiley Periodicals, Inc.)

The effect of the degree of acetylation (DA) of 3D chitosan (Ch) scaffolds on the inflammatory reaction was investigated. Chitosan porous scaffolds with DAs of 4 and 15% were implanted using a subcutaneous air-pouch model of inflammation. The initial acute inflammatory response was evaluated 24 and 48 h after implantation. To characterize the initial response, the recruitment and adhesion of inflammatory cells to the implant site was studied. The fibrous capsule formation and the infiltration of inflammatory cells within the scaffolds were evaluated for longer implantation times (2 and 4 weeks). Chitosan with DA 15% attracted the highest number of leukocytes to the implant site. High numbers of adherent inflammatory cells were also observed in this material. For longer implantation periods Ch scaffolds with a DA of 15% induced the formation of a thick fibrous capsule and a high infiltration of inflammatory cells within the scaffold. Our results indicate that the biological response to implanted Ch scaffolds was influenced by the DA. Chitosan with a DA of 15% induce a more intense inflammatory response when compared with DA 4% Ch. Because inflammation and healing are interrelated, this result may provide clues for the relative importance of acetyl and amine functional groups in tissue repair and regeneration.

Water-soluble chitosan having double bonds (CS-MA-LA) was synthesized by sequential grafting of methacrylic acid (MA) and lactic acid (LA) via the reaction between amino groups and carboxyl groups under the catalysis of carbodiimide. Its molecular structure was verified by FTIR and (1)H NMR characterizations. Elemental analysis measured grafting ratios of 19% and 10.33% for MA and LA, respectively. CS-MA-LA was readily soluble in pure water and did not precipitate till pH 9. Gelation of the CS-MA-LA was realized by thermal treatment at body temperature under the initiation of a redox system, ammonium persulfate (APS)/N, N,N',N'-tetramethylethylenediamine (TEMED). The gelation time could be mediated in a wide range, e.g. from 6 to 20 min, by reaction temperature and/or initiator's concentration. 3T3 fibroblast culture showed that the cytotoxicity of the hydrogel extractant was dependent on the cell seeding number and the initiator's concentration. With enough number of cells (>2.5 x 10(4)) and low initiator's concentration (5 mM), the cytotoxicity introduced by the initiator is very minimal and negligible. Although the hydrogel could cause acute inflammation and foreign body reaction, no tissue necrosis and malignant infection were evidenced in vivo, demonstrating that the material has better histocompatibility. These features have endowed the chitosan with great opportunity as injectable biomaterials, which may find wide applications in the rapidly developed fields such as tissue engineering and orthopedics.