Chitosan Gel Sheet Containing Polymeric Micelles: Synthesis and Gelation Properties of PEG-Grafted Chitosan.

Chikara Yoshida,Tomoki Ito,Yoshihiko Murakami,Yusuke Uchida,Taku Takami

doi:10.3390/ma10091075

Abstract

Wound-dressing sheet biomaterials can cover wound sites and enhance wound healing. In this study, a detailed evaluation of the factors affecting both the PEG modification percentage (PMP) in poly(ethylene glycol) (PEG)-grafted chitosan synthesis and the gelation properties of PEG-grafted chitosan was presented for constructing our novel hybrid hydrogel sheet consisting of PEG-grafted chitosan (a gel-forming polymer) and a reactive polymeric micelle (a crosslinker). It was confirmed that various factors (i.e., the weight ratio of PEG/chitosan, the pH of the buffer solution, reaction times, and reaction temperatures) in the preparation stage of PEG-grafted chitosans affected the PMP of PEG-grafted chitosans. Furthermore, the PMP of PEG-grafted chitosans affected their gelation properties. Finally, a ‘flexible’ hydrogel sheet that can be reversibly dried and moistened was successfully obtained. The dried rigid, thin sheet is expected to be suitable for stable preservation. The results obtained in this paper show that the incorporation of drug carriers into biomaterials is a novel approach to improve functionality.

Highlights

Conventional dry wound-dressing materials often hinder wound healing by absorbing exudates, including macrophages and growth factors
Acetal-poly(ethylene glycol) (PEG) was used as a modifier of chitosan because the aldehyde group possessed the feature wherein acetal-PEG could bind with the amino group present on the chitosan backbone
The aldehyde-terminated polymeric micelles were used as crosslinkers because the aldehyde group on the surface of the polymeric micelle could bind with the amino groups of the chitosan backbone, i.e., the hydrogel was formed according to the Schiff base formation reaction

Summary

Introduction

Conventional dry wound-dressing materials (such as gauze) often hinder wound healing by absorbing exudates, including macrophages and growth factors. The controlled sustained release of compounds from hydrogels is difficult because the release mechanism depends mainly on two phenomena: the degradation of polymeric networks and the diffusion of compounds through the hydrogel medium. In these regards, we have developed a novel ‘hybrid’ approach: the incorporation of functional block copolymers and/or their self-assembly (polymeric micelles) into base materials (such as gel [3,4,5,6,7], sheets [8,9,10], and particles [11,12,13,14,15]) for the construction of biomaterials for drug delivery systems. The hybrid material design approach (i.e., the incorporation of micelles into hydrogels) is expected to help give the hydrogels various controllable drug release properties

Methods

Results

Conclusion