Microstructure and Electrochemical Behavior of Laser Cladded HA Coating on Pure Titanium TA2

Hydroxyapatite （HA, Ca10（PO4）6（OH）2） coating was fabricated on pure Ti （TA2） by laser cladding technology. The phase structure, microstructure, microhardness and electrochemical behavior of the laser cladded HA coating in artificial body fluid were investigated. The results show that the HA coating is mainly composed of highly crystallized HA. A transitional layer between HA coating and Ti substrate is formed. Microhardness measurement shows the gradually increasing of microhardness from 150 HV at TA2 substrate to 600 HV at transitional layer, and followed by a decreasing to 400 HV at HA coated layer. Electrochemical corrosion tests show that the HA coating has higher open circuit potential , lower corrosion current density and corrosion rate in comparison to the TA2 substrate.

In vitro evaluation of degradation,cytocompatibility and antibacterial property of polycaprolactone/hydroxyapatite composite coating on bioresorbable magnesium alloy

Polycaprolactone/hydroxyapatite(PCL/HA)composite coating was fabricated by a combination of hydrothermal and dipping methods to delay the degradation of Mg alloy AZ31 as bioresorbable materials.The PCL/HA coating was composed of nano rod-shape HA crystals and PCL filled in the space of HA crystals.Compared with the single HA coating,the binding strength between the PCL/HA composite coating and Mg alloy was obviously improved and the PCL/HA coating still adhered to the surface of AZ31 substrate even after 38 days of immersion.The electrochemical corrosion rate of HA coated sample was reduced by ten times after being filled by PCL.The electrochemical impedance spectroscopy(EIS)and immersion test results showed that the PCL/HA composite coating could provide a more effective barrier for Mg substrate than the HA coating alone.The cytocompatibility and the antibacterial property of HA coating and PCL/HA coating were evaluated by culturing with bone marrow-derived mesenchymal stem cells(BMSCs)and methicillin-resistant staphylococcus aureus(MRSA)for 24 h under direct culture conditions,respectively.The PCL/HA composite coating showed better BMSC cell compatibility,more suitable for BMSC adhesion than HA coating alone and showed a potential application prospect as a biological materials.However,from the perspective of clinical applications,the antibacterial property of PCL/HA composite coating needs to be further improved.

Forsterite-hydroxyapatite composite scaffolds with photothermal antibacterial activity for bone repair

Bone engineering scaffolds with antibacterial activity satisfy the repair of bacterial infected bone defects,which is an expected issue in clinical.In this work,3D-printed polymer-derived forsterite scaffolds were proposed to be deposited with hydroxyapatite(HA)coating via a hydrothermal treatment,achieving the functions of photothermal-induced antibacterial ability and bioactivity.The results showed that polymer-derived forsterite scaffolds possessed the photothermal antibacterial ability to inhibit Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)in vitro,owing to the photothermal effect of free carbon embedded in the scaffolds.The morphology of HA coating on forsterite scaffolds could be controlled through changing the hydrothermal temperature and the pH value of the reaction solution during hydrothermal treatment.Furthermore,HA coating did not influence the mechanical strength and photothermal effect of the scaffolds,but facilitated the proliferation and osteogenic differentiation of rat bone mesenchymal stem cells(rBMSCs)on scaffolds.Hence,the HA-deposited forsterite scaffolds would be greatly promising for repairing bacterial infected bone defects.