The Study Of Protein Diffusion In Zwitterionic Hydrogels And Establishment Of Diffusion Model

The adjustment and prediction of the diffusion coefficient of solute is significant in the process of biological transport and the biomedical application of hydrogel.Protein as a common solute in biological transport,the diffusion behavior of protein in hydrogel is particularly important.Recently,zwitterionic hydrogels are wildly concerned in biomedical field because of excellent biochemical properties.Therefore,this work takes the diffusion behavior of protein in zwitterionic hydrogels as target,the aim is to establish a new diffusion model and enhance its ability to predict the diffusion behavior of proteins in hydrogels.The randomness of solute movement in hydrogel network was reconsidered,and a physical diffusion model RMP-1 based on obstruction theory was established in this study.Take into account the physical properties of solute and polymer chain and the interaction of between both of them,a variable a was introduced to RMP-1 model and derived RMP-2,RMP-3 models.Zwitterionic poly(sulfobetaine methacrylate)(PSBMA)hydrogels with wide range and fine adjustable mesh size were prepared and applied as an efficient experimental platform for model validation,the mesh size was adjusted by changing crosslinking density and ionic strength of swelling medium.The structure characteristics and related parameters of PSBMA hydrogel were also investigated.Lysozyme(LYZ),Bovine serum albumin(BSA)and Immunoglobulin(IgG)with different sizes,isoelectric points and flexibilities were used as model proteins.The diffusion coefficients of proteins in PSBMA hydrogels were determined by fluorescence recovery after photo-bleaching(FRAP)measurements and the results were used for model validation.The measured diffusion coefficients were compared with the predictions of previously reported model and new model,it was found that our model presented a better predictive ability.Furthermore,the assessment of our model revealed that protein diffusion in PSBMA hydrogel would be affected by the physical properties of protein and PSBMA network.It is also confirmed that the diffusion behavior of protein in zwitterionic hydrogels can be adjusted by changing crosslinking density of hydrogel and ionic strength of swelling medium.This indicated that the zwitterionic hydrogels can be used as an effective diffusion matrix for the adjustment of solute diffusion coefficient.The precise adjustmet of the diffusion coefficient of the solute in zwitterionic hydrogels will have a wide range of applications in biomedical field.