Construction Of Polypyrrole-polydopamine Composite Coating On Titanium Implant Surface

In research and clinical application of metal bone implant material,coating technology can effectively improve the biological activity and enhance the bonding strength between implant and bone interface of metal implants.It also could inhibit the dissolution of metal ions,which lead to the perfect bone integration.while for the commonly used coating(such as hydroxyapatite coating)in clinical,the binding force between the substrate and coating will reduced or the coating may even dissolute with time,the occurrence of these phenomena tend to cause the failure of planting.Therefore,construct a new type of implant coating which has good corrosion protection performance,biological activity and osteogenesis induction activity and high bonding strength between the substrate and coating is particularly important.Polypyrrole(PPy)was a kind of typical conductive polymer,its good biocompatibility,excellent electrical conductivity and good anti-corrosion performance make it become a good kind of biological coating material which could have great application prospect.Dopamine(DA)was a neurotransmitter,which famous for its good biological activity and could form adhesive film in almost all organic and inorganic solid material surface,makes it a good surface modification materials.Therefore,this article constructs two kinds of adhesive polypyrrole-polydopamine(PPy-PDA)composite coatings on titanium implant surface based on PPy and PDA,the physical and chemical test and osteoblast cultivated on composite coating were investigated to evaluate the corrosion resistance and biocompatibility of the PPy-PDA composite coatings.This study was divided into two parts,the main works and results were as follows:1)The construction of PPy-PDA double-deck composite coating:A two-step method was used to synthesis PPy-PDA double-deck composite coating on titanium implant surface,a thin PDA layer was firstly deposited on the chemically pretreated titanium implant surface via chemical oxidation in the alkalinity solution,then the PPy layer was electrodeposited on the PDA modified Ti surface through electrochemical method.The physical and chemical performance of PPy-PDA double-deck composite coating was investigated,the results showed the coating was adhesive and with excellent corrosion protection performance,at the same time it showed better electrochemical stability and hydrophilicity with kept good electrical conductivity and electrochemical activity from pure PPy coating.2)The construction of PPy-PDA copolymer composite coating:One step electrochemical method was used to prepare PPy-PDA copolymer composite coating in the electrolyte solution containing both pyrrole monomer and dopamine on titanium implant surface,the physical and chemical properties and biological properties of the coating were studied.The results showed that the copolymer has excellent bonding strength between coating and substrate while keeping the good electrochemical activity and conductivity of pure PPy coating.Copolymerization with DA also gives the PPy nanowires morphology with sticky superhydrophobic performance.MTT colorimetry test and cell staining were investigate to evaluate the biocompatibility of PPy/PDA copolymer composite coating and pure PPy coating,the results showed the MC3T3-E1 cell adhesion and proliferation on the copolymer coating was better than pure PPy coating,which means the presence of PDA in copolymer coating greatly enhanced its biocompatibility,make it very suitable coating materials for osteoblast cell adhesion and proliferation.