Orientation in multi-layer chitosan hydrogel: morphology, mechanism and design principle

Abstract

Hydrogels with organized structure have attracted remarkable attentions for bio-related applications. Among the preparation of hierarchical hydrogel materials, fabrication of hydrogel with multi-layers is an important branch. Although the generation mechanism of layers had been fully discussed, sub-layer structure was not sufficiently studied. In this research, multi-layered chitosan hydrogel with oriented structure was constructed, and the formation mechanism of orientation was proposed, based on gelation behavior and entanglement of polymer chains in the hydrogel-solution system. Employing the layered-oriented characteristic, chitosan hydrogel materials with various shapes and structure can be designed and fabricated.

Chitosan Hydrogel Structure Modulated by Metal Ions

“…The basic way to prepare a CS hydrogel is solubilisation of CS in an acidic aqueous medium. The system lays the foundations of CS material preparation in many aspects, including fabrication of sophisticated organization21222324 and preparation of CS-based composite materials252627.…”

Investigation of gelling behavior of thiolated chitosan in alkaline condition and its application in stent coating

“…4b, both CS and TCS appeared to be turbid but resulted in liquid for CS and in gel for TCS 6 h later. A possible explanation is that the low concentrations of polymer and slow rate of neutralization in this study are insufficient to maintain stable chain entanglement and coagulation of chitosan (Nie et al, 2015) The results indicate that, upon neutralization, although chitosan itself plays no direct role in gel formation, its phase transition probably acts positive parts in gelation through chain entanglement and coagulation.…”

Surface charge switchable and pH-responsive chitosan/polymer core-shell composite nanoparticles for drug delivery application

“…According to Fick's first law, the solute (NH 3 ) diffused from a high concentration region (NH 3 droplet) to a low concentration region (chitosan droplet) across a concentration gradient. This gradient diffusion of the alkali solution has been found to enable formation of multilayer chitosan hydrogel instead of forming cross-linked gel simultaneously as reported in literature [27]. According to their study, the gelation speed of the chitosan solution decreased while the alkali solution diffused from the top to the bottom, leading to formation of multilayer chitosan hydrogel with different structure.…”

“…The critical polymer concentration has been discovered to be 0.56 wt% for the chitosan of molecular weight of 200 kDa as reported in literature [27]. Since the molecular weight of the chitosan in the present study is about 500 kDa, the critical concentration should be lower than 0.56 wt%.…”