Preparation And Anti-biofouling Properties Of Biomimetic Bacterial Cellulose Membranes

Bacterial cellulose（BC）is a natural polymer material exhibiting a three-dimensional nanofiber network structure,displays a good biocompatibility and a series of excellent physical and chemical properties.BC can be used as substrate to prepare various biomedical materials by physical blending or chemical modification,and has broad application prospects.The research of BC modification is increasing.In recent years,Biomimetic synthesis of materials is an important strategy which is expected to improve the biocompatibility and biofunctionalization of materials.In this paper,based on retaining BC-like extracellular matrix three-dimensional nanofiber network structure,the pretreatment of BC and further cell membrane biomimetic technology of zwitterionic phosphocholine（PC）modification were studied.Furthermore,the structure,physicochemical and biological properties of biomimetic PCBC were characterized and evaluated systematically.On the basis of preserving the three-dimensional nanofiber network structure,the BC was pretreated in two different ways.First,sodium periodate was used to oxidize BC to prepare dialdehyde bacterial cellulose（oxidized bacterial cellulose,OBC）nanofiber clusters.Second,theβ-cyclodextrin was grafted to OBC to prepare cyclodextrin modified bacterial cellulose（BC-CD）based on the Schiff base reaction.In order to explore the appropriate oxidation method,we explored the influence of sodium periodate concentration,oxidation time and reaction p H on aldehyde content of OBC.The results revealed that the aldehyde content of OBC increased with increasing the oxidant concentration and prolonging the reaction time.However,when the BC oxidized at a concentration of Na IO₄ exceeded 0.1 mol/L for 24 h,the fiber structure of BC was destroyed because of"over-oxidation"and dissolution.It was an appropriate oxidation method which BC reacted with Na IO₄ solution at a concentration of 0.018 mol/L for 96 h to preserve the three-dimensional nanofiber network structure of BC,and the aldehyde content of OBC prepared by this way was 2649±83μmol/g which meant that 21.46%of the hydroxyl group was oxidized to the aldehyde group.In addition,the cyclodextrin modified bacterial cellulose（BC-CD）was obtained by chemically coupling aminatedβ-cyclodextrin onto the surface of OBC nanofiber clusters based on the Schiff base reaction.Then hydroxylamine hydrochloride titration method was used to measure the significant differences in aldehyde content before and after Schiff base reaction.And the FTIR analysis showed that the characteristic stretching vibration of C=N appeared in the infrared spectrum of BC-CD.X-ray photoelectron spectroscopy（XPS）analysis showed that two peaks of C=N and C-NH-C were obtained from N peak of XPS spectra.These results indicated that BC-CD was prepared successfully.The materials functionalized with zwitterionic groups are considered to be promising anti-adhesion materials.In this study,a novel cell membrane biomimetic phosphorylcholine（PC）modified bacterial cellulose（PCBC）membrane was prepared based on the Pudovik reaction of oxidized BC nanofiber clusters and then solution casting technology.The composition analysis of PCBC membranes confirmed the existence of zwitterionic PC groups on the membrane surfaces.And the SEM results revealed that the surface morphology of the PCBC membranes retained three-dimensional network nanofiber structure.Compared with BC membranes,PCBC membranes exhibited better hydrophilicity,similar tensile strength,but decreased rupture strain and poor thermal stability.Safety and non-toxicity of organisms are basic requirements of biological material.The biocompatibility of PCBC membranes was evaluated by hemolysis rate and cytotoxicity test.The results proved that PCBC membranes were non-hemolytic and non-cytotoxic like BC membranes.The anti-biofouling performance investigation revealed that PCBC membranes showed significantly reduced protein adsorption for bovine serum albumin（BSA）,as well as inhibited cell attachment for both L929 cells and macrophage RAW 264.7.In summary,oxidized bacterial cellulose which retained the three-dimensional nanofiber network structure was prepared by gentle oxidation.And the cell membrane biomimetic PCBC membrane was obtained based on the Pudovik reaction and showed a good biocompatibility,resistance to protein and cell adhesion properties.It has an attractive application prospects in the field of anti-biofouling medical materials.