Preparation Of Dextran-based Hydrogel By Click Chemistry And The Study Of Protein Diffusion

The regulation of solute diffusion in hydrogels is of great significance in biomedical fields.For cell encapsulation,cells encapsulated in hydrogels not only require the efficient diffusion and exchange of nutrients and metabolic wastes,but also require effective isolation of some solute molecules,such as cytotoxic immune molecules to maintain cell viability.Therefore,it is important to establish the hydrogel with controllable structural parameters and study the diffusion behavior of different solute molecules in hydrogels.The mesh size was an important parameter to describe the hydrogel structure and the protein was a typical biological diffusion solute.Therefore,the protein was chosen as diffusion solute and a novel biocompatible hydrogel system with tunable mesh size was constructed via click chemistry to investigate the relationship between the mesh size of the hydrogel and the diffusion behavior of proteins in hydrogels.In this paper,on the basis of click chemistry,methacryloyl-modified dextran(Dex-GMA),dithiol-functionalized PEG(PEG-SH)and PSBMA-SH were chosen as main chain and crosslinker,respectively.Then a series of clickable Dex-GMA/PEG-SH(D/P)hydrogels were prepared via"thiol-ene"click reaction by changing precursor concentration and ene/thiol molar ratio.And we tried to prepared Dex-GMA/PSBMA-SH(D/S)hydrogels.The polymers and hydrogels were characterized by proton nuclear magnetic resonance spectroscopy(~1H-NMR)and fourier transform-infrared spectroscopy(FT-IR).The swelling properties and mechanical properties of D/P hydrogels were characterized by swelling test and compressive test.The results showed that the precursor concentration and ene/thiol molar ratio could affect swelling behavior and mechanical properties of hydrogels in macroscopic view.On the basis of equilibrium swelling theory and swelling test result,the mesh size of hydrogel was calculated.At the same time,using FITC-labeled lysozyme(FITC-Lyz)and FITC-labeled bovine serum albumin(FITC-BSA)with different sizes as model proteins,their diffusion behaviors in D/P hydrogel were investigated in detail.The effective diffusion coefficients of the two kinds of proteins in different hydrogels were also calculated.The relationship between the diffusion coefficient of the proteins in D/P hydrogels and the mesh size of the hydrogels was studied as well.The results proved that the mesh size of hydrogel could be controlled by precursor concentration and ene/thiol molar ratio via click chemistry,leading to the tunable diffusion of proteins in hydrogel.