Establishment Of P(VDF-TrFE) Films Covered ITO Microelectrodes And Their Surface Potentials Mediating MSCs Osteogenic Differentiation

Surface potential of biomaterials plays a critical role in mediating cellular differentiation and directing cellular fate.However,relevant researches generally only focus on regulating one kind of surface potential to affect cell behaviors.There are few reports that reasonably combine and apply different kinds of surface potentials to maximize the function of promoting osteogenic differentiation.In this paper,we covered indium tin oxide?ITO?planar microelectrode with ferroelectric polyvinylidene fluoride trifluoroethylene?P?VDF-TrFE??film?ie P?VDF-TrFE?@ITO?to constructed a surface which could manipulating both long-range surface potential?induced by electric field?and short-range surface potential?induced by charges?.And from the perspective of the synergy of long-range and short-range surface potentials,the effects and mechanism of surface potential on osteogenic differentiation of mesenchymal stem cells?MSCs?were explored.The results of this work were mainly achieved as the following:Nano-scale and micro-scale P?VDF-TrFE?films were prepared by using spin-coating and type-casting,respectively,so n-P?VDF-TrFE?@ITO and?-P?VDF-TrFE?@ITO were well constructed.For spin-coating method,the thickness of the film mainly relies on the solution concentration and spin coating layers.When the thickness of nano-film reaches 470 nm,it can well isolate the patterned morphology,microcurrent and possible electrochemical products of ITO microelectrode.As for type-casting method,the thickness of the film is only closely related to the solution concentration.When the thickness of micron-film reaches 3.5?m,P?VDF-TrFE?exhibits good crystallinity and can be effectively polarized.By applying electric field to ITO microelectrode and polarizing P?VDF-TrFE?film,?-P?VDF-TrFE?@ITO can individually or simultaneously possess long-range and short-range surface potentials,and their values are regulated by applied voltage(V_EF)and piezoelectric coefficient(d₃₃),respectively.When?-P?VDF-TrFE?@ITO generated single long-range or short-range surface potential and then acted on MSCs,both two potentials could effectively promote the proliferation and osteogenic differentiation of MSCs,and the optimal value of long-range and short-range surface potentials were corresponded to V_EF=1 V and d₃₃=-1.5 pC/N,respectively.When long-range and short-range surface potentials were manipulated simultaneously,the effect of surface potential on promoting MSCs osteogenic differentiation could be further significantly enhanced.The optimal combination was exactly the superposition of the optimal value of single long-range or short-range surface potential,showing that these two surface potentials played independent roles in enhancing cellular osteogenic differentiation.Genes related to calcium-and integrin-mediated osteogenic signaling pathways were tested,and the mechanism of?-P?VDF-TrFE?@ITO surface potential on osteogenic differentiation of MSCs was analyzed.It is suggested that long-range and short-range surface potentials activate calcium-mediated PKC and integrin-mediated FAK upstream signaling pathways which could crosstalk in the downstream of the signaling cascade,and ERK is intensively activated to trigger a significant up-regulation in osteogenic gene Runx2 expression.The independence of these two upstream signaling pathways determines the apparent superposition of effects of long-range and short-range surface potentials.This work makes important contributions to deepening the understanding of the interaction between surface potential and cells,and also provides theoretical guidance for designing the surface of implants.