Development of antimicrobial and scar preventive chitosan hydrogel wound dressings

Preparation and cytotoxicity of chitosan-based hydrogels modified with silver nanoparticles

Chitosan based hydrogels are commonly applied in various fields of medicine and pharmacy. Modification of hydrogel polymers using nanosilver particles may result in formation of materials with enhanced antibacterial properties. In this article synthesis of hydrogel materials based on chitosan and modified with silver nanoparticles is presented. First, preparation and characterization of silver nanoparticles using UV-vis spectroscopy has been shown. Hydrogels modified with nanosilver particles were subjected to the measurements of swelling ability and in vitro tests in distilled water and Simulated Body Fluid (SBF), respectively. Additionally, evaluation of antibacterial properties against Staphylococcus aureus and Enterococcus faecalis as well as results of cytotoxicity of hydrogel materials modified with silver nanoparticles conducted by means of XTT and MTT assays using dermis cells BJ (CRL-2522TM) have been presented.

Synthesis and in vitro antimicrobial and antioxidant activities of quaternary ammonium chitosan modified with nisin

Nisin had been grafted onto quaternary ammonium chitosan (QCS) through an enzyme-catalyzed reaction to enhance its limited antimicrobial activity. QCS was synthesized by incorporating N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride (CHPTAC) onto chitosan's primary amine group. The modification had been confirmed by FT-IR and ¹H NMR spectroscopy. Degree of substitution (DS) of QCS-nisin could be controlled by adjusting the reaction conditions. The synthesized compounds were screened in vitro to evaluate their antimicrobial and antioxidant activities. The results suggested that QCS-nisin significantly suppressed the growth of both gram-positive bacteria and gram-negative bacteria; The antioxidant effects on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, hydroxyl radical and hydrogen peroxide (H₂O₂) proved to be enhanced with increasing DS and concentration. In addition, QCS-nisin showed excellent moisture absorption and retention properties; MTT assay exhibited that QCS-nisin revealed low cytotoxicity effects on cultured NIH-3T3 fibroblasts. These results suggest that QCS-nisin would appear to be a promising candidate for wound dressing application.

Nerve transection repair using laser-activated chitosan in a rat model

OBJECTIVES/HYPOTHESIS

Cranial nerve transection during head and neck surgery is conventionally repaired with microsuture. Previous studies have demonstrated recovery with laser nerve welding (LNW), a novel alternative to microsuture. LNW has been reported to have poorer tensile strength, however. Laser-activated chitosan, an adhesive biopolymer, may promote nerve recovery while enhancing the tensile strength of the repair. Using a rat posterior tibial nerve injury model, we compared four different methods of nerve repair in this pilot study.

STUDY DESIGN

Animal study.

DESIGN

Animals underwent unilateral posterior tibial nerve transection. The injury was repaired by potassium titanyl phosphate (KTP) laser alone (n = 20), KTP + chitosan (n = 12), microsuture + chitosan (n = 12), and chitosan alone (n = 14). Weekly walking tracks were conducted to measure functional recovery (FR). Tensile strength (TS) was measured at 6 weeks.

RESULTS

At 6 weeks, KTP laser alone had the best recovery (FR = 93.4% ± 8.3%). Microsuture + chitosan, KTP + chitosan, and chitosan alone all showed good FR (87.4% ± 13.5%, 84.6% ± 13.0%, and 84.1% ± 10.0%, respectively). One-way analysis of variance was performed (F(3,56) = 2.6, P = .061). A TS threshold of 3.8 N was selected as a control mean recovery. Three groups-KTP alone, KTP + chitosan, and microsuture + chitosan-were found to meet threshold 60% (95% confidence interval [CI]: 23.1%-88.3%), 75% (95% CI: 46.8%-91.1%), and 100% (95% CI: 75.8%-100.0%), respectively.

CONCLUSIONS

In the posterior tibial nerve model, all repair methods promoted nerve recovery. Laser-activated chitosan as a biopolymer anchor provided good TS and appears to be a novel alternative to microsuture. This repair method may have surgical utility following cranial nerve injury during head and neck surgery.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:E253-E257, 2017.

A novel hydrogel of poloxamer 407 and chitosan obtained by gamma irradiation exhibits physicochemical properties for wound management

Application of polymers cross-linked by gamma irradiation on cutaneous wounds has resulted in the improvement of healing. Chitosan (CH) and poloxamer 407 (P407)-based hydrogels confer different advantages in wound management. To combine the properties of both compounds, a gamma-irradiated mixture of 0.75/25% (w/w) CH and P407, respectively, was obtained (CH-P), and several physical, chemical, and biological analyses were performed. Notably, gamma radiation induced changes in the mixture's thermal behavior, viscosity, and swelling, and exhibited stability at neutral pH. The thermal reversibility provided by P407 and the bacteriostatic effect of CH were maintained. Mice full-thickness wounds treated with CH-P diminished the wound area during the first days. Consequently, with this treatment, increased levels of macrophages, α-SMA, and collagen deposition in wounds were observed, indicating a more mature scar tissue. In conclusion, the new hydrogel CH-P, at physiologic pH, combined the beneficial characteristics of both polymers and produced new properties for wound management.

Comparison of Hydrogels Based on Commercial Chitosan and Beetosan® Containing Nanosilver

Two series of hydrogels on the basis of commercial chitosan and chitosan derived from naturally expired honeybees are presented in this article. Sorption capacity and behavior of both kind of materials in simulated body fluids such as Ringer's liquid or artificial saliva have been determined and compared. Presence of functional groups in synthesized materials have been determined by means of FT-IR spectroscopy. Structure and homogeneity of their surface have been defined using Scanning Electron Microscopy. Based on the conducted research, it can be stated that both chitosan and Beetosan® hydrogels have very similar characteristics. It is worth noting that synthesis of such materials is environmentally friendly and leads to obtaining polymers that can be used for biomedical applications. Tested materials are characterized by low sorption capacity and do not have a negative impact on simulated body fluids. Moreover, based on the cell lines studies, it can be stated that Beetosan® hydrogels have a negative influence on cells of cancerous origin and, what is important, significantly less adverse effects on fibroblasts.