Fabrication And Evaluation Of Hydroxy Ethyl Cellulose/Soy Protein Isolate/Polypyrrole Conductive Composite

Objective:To prepare,character and valuate the structure,physicochemical properties and biocompatibility of hydroxyethyl cellulose/soy protein isolate/polypyrrole conductive composites for the exploring their potential applications as biomaterials.Methods:Firstly,based on the previous work of our laboratory,hydroxyethyl cellulose/soy protein isolate(HEC/SPI,3:7)composite films were prepared by crosslinking HEC and SPI with epichlorohydrin(ECH)using the process of casting and evaporating.And then,a series of conductive composite films(HEC/SPI/PPY)with different polypyrrole(PPY)content was prepared through in-situ polymerization of PPY onto the matrix HEC/SPI films.The structure and properties of the HEC/SPI/PPY composite films were characterized evaluated by conductivity measurement,scanning electron microscope(SEM)and transmission electron microscopy(TEM)observation,Fourier transform infrared spectroscopy(FTIR)and X-ray diffraction(XRD)analysis,water absorption and water retention rate testing,and mechanical property testing.And the hemocompatibility was evaluated through haemolysis rate measurement,and platelet and erythrocyte adhesion testing.Subsequently,the cell compatibility of the HEC/SPI/PPY films with rat schwann cells was evaluated by[3-(4,5-dimethylthiazol-2-yl)-2,5-diphe-nyltetrazolium bromide](MTT)assay,cell reactive oxygen species(ROS)assay,and cell co-culture experiments.Secondly,a series of HEC/SPI/PPY conductive composite sponges with different PPY contents were prepared by the freeze-drying according to the above method.After that,the structure,physicochemical properties,blood compatibility and cell compatibility of the composite sponges were also evaluated.Thirdly,a series of HEC/SPI/PPY composite sponges with the same chemical composition to HEC/SPI/PPY conductive sponges but different microstructures were prepared by controlling the concentration of the original raw solution.Effects of the pore structure of the composite sponges and the pressing on the conductivity and other physical properties of the HEC/SPI/PPY conductive sponges were evaluated by a series of methods.All the three parts of this work was to provide experiment data and support for the potential applications of HEC/SPI/PPY conductive films and sponges in the field of biomaterials.Results:Firstly,for the HEC/SPI/PPY conductive films,the results from SEM,TEM,FTIR,XRD showed that PPY was mainly distributed on the surface of the HEC/SPI matrix.The PPY content on the films could be controlled by the in-situ polymerization cycles of PPY.With the increase of the numbers of in-situ polymerization cycle reaction,the content and conductivity of PPY increased,reaching a maximum of 6.8%and 0.42 S/m respectively.PPY played a role to enhanced the tensile strength of the composite materials,and reduced the water absorption.The HEC/SPI/PPY conductive films also showed cytocompatibility and hemocompatibility.Secondly,for the HEC/SPI/PPY composite sponges,PPY distributed on the surface and inside of the composite sponges.The content of PPY and conductivity of the sponges(reaching 50%and 61 S/m,respectively)were higher than those of the corresponding films prepared with the same original chemical compositions.Introduction of PPY into HEC/SPI composite sponges also increased its compressive strength and water retention.The sponge kept a certain of recovery after pressed.The sponges also showed hemocompatibility and cytocompatibility,and the three-dimensional and porous structure of the sponges was more beneficial than the films for cell to grow,adhere and proliferate.Thirdly,for the conductive sponges with different porosity and microstructure,their conductivity could be affected by the factors such as pore size,PPY content and pressure,which showed a certain of piezoelectric properties.Conclusion:A series of new conductive composite films and sponges was fabricated through in-situ polymerization of polypyrrole onto the HEC/SPI films or sponge matrix.The structure,conductivity and biological properties of the composite films and sponges could be changed by the PPY content and fabrication process.Especially,the conductivity of the composite sponge could also be affected by the pore structure of the sponge and by the degree of compression.These two types of materials also had good biocompatibility and potential application as conductive biomaterials such as nerve conduits or wearable medical devices.