Regulation Of Polythiophene/Poly(Ehyl Lactide-Lactide) Complex With Different Electrical Conductivity On Behaviors Of Cells

Conductive polymers（CPs）with the ability to regulate cell behavior and promote the regeneration of damaged tissues,which have been researched extensively.The conductivity of CPs close to that of metals and inorganic semiconductors,and it can be greatly improved by doping.However,the effect of conductivity on cell behavior has been reported rarely.In this study,poly（3-hexylthiophene）（P3HT）with a molecular weight of 10 kDa was designed and synthesized by Kumada catalyst transfer polycondensation method,which has the advantages of controllable molecular weight,narrow molecular weight distribution and clear end groups.P3HT was mixed with biodegradable poly（glycolide-lactide）（PLGA）to obtain an electroactive P3HT/PLGA composite.Five groups of composites with incremental conductivity(10^-7,10^-6,10^-5,10^-44 and 10^-2 S/cm)were prepared by controlling the doping time（0 s,5 s,30 s,2 min and 5 min）with FeCl₃ as a dopant.The electrochemical and surface properties of the conductive composites were investigated by X-ray photoelectron spectroscopy,cyclic voltammetry,contact angle measurement,scanning electron microscope and atomic force microscope.It was proved that the surface properties and hydrophilicity of composite materials with different conductivity do not affect the cell behavior difference,and then the effect of conductivity on cell behavior was researched.It was found that P3HT/PLGA composite with conductivity of 10^-2 S/cm can promote the proliferation of Mouse osteogenic precursor cells（MC3T3-E1 cells）significantly.The adhesion and growth of filamentous pseudopod of MC3T3-E1 cells were promoted by P3HT/PLGA composites with conductivity of 10^-5,10^-4 and 10^-2 S/cm.When the conductivity of P3HT/PLGA composites was increased to 10^-2 S/cm,the alkaline phosphatase activity,cell mineralization and type I collagen expression levels of MC3T3-E1cells were increased.Compared with MC3T3-E1 cells,Rat pheochromocytoma cells（PC12cells）showed more pronounced proliferative responsiveness to P3HT/PLGA composites.As the conductivity of P3HT/PLGA composites increased,the proliferation effect of PC12 cells on composites was enhanced.The growth and elongation of PC12 cells synapses were promoted by the material with high conductivity under the induction of Nerve growth factor.