Ultrasonic Micro-arc Oxidation Modification Of Ti-Cu Alloy And Its Biological Properties

Titanium and titanium alloys are widely used in biomedical implants due to their excellent mechanical properties and biocompatibility,especially in the fields of artificial joints and dental implants.Inflammatory infections and low osseointegration are two major clinical problems.Copper has certain antibacterial ability as an essential trace element in human body.In this study,Ti-3Cu alloy was used as raw material and subjected to ultrasonic micro-arc oxidation(UMAO)surface treatment to form porous oxide coating in order to changes the distribution and existing form of copper,and in turn to improves the antibacterial property,but also ensures good cell compatibility.The physical and chemical properties of the UMAO Ti-Cu alloys were studied by scanning electron microscopy,X-ray diffractometry,X-ray photoelectron spectroscopy,inductively coupled plasma mass spectrometer,contact angle meter,confocal microscopy and electrochemical workstation.Staphylococcus aureus was co-cultured with Ti-Cu alloys and UMAO Ti-Cu alloys.The short-term and long-term antibacterial properties of the alloy were studied by means of plate counting,staining,bacterial fixation,etc.,and the antibacterial mechanism was analyzed.The cytotoxicity was also assessed with MC3T3-E1 cells by CCK-8 cell proliferation test,cytoskeleton staining,and cell fixation.The following conclusions were obtained:Ultrasonic micro-arc oxidation treatment of Ti-3Cu alloy in silicon and phosphorus plating bath produced a porous coating with a thickness of 5-15?m.The main components of the coating were rutile,anatase,copper oxide and silicon phosphorus oxide.The surface roughness of the alloy increased after the UMAO,and the surface hydrophilicity was remarkably improved due to the existence of microscopic porous structure and metastable anatase.The corrosion performance of the UMAO Ti-Cu alloys in cell culture solution was tested by electrochemical test.It was found that the corrosion resistance of the alloys was improved by UMAO.The ion-dissolution experiment found that the titanium ion release concentration from the alloy before and after micro-arc oxidation did not change significantly.However,the amount of copper ion release concentration increased remarkably,and the release rate began to decrease slowly after five days.The UMAO Ti-3Cu exhibited very strong antibacterial properties,the antibacterial rate was stable above 99%,even after being soaked in the bacterial solution containing Staphylococcus aureus and physiological saline for 20 days.The antibacterial rates were still as high as 97%and 91%after 30 days' soaking,respectively.This was thought to be related mainly to the copper ions release caused by the solution and bacteria.Co-culture experiments with MC3T3-E1 showed that there was no significant difference in the relative growth rate of the alloy before and after UMAO after 1 day incubation,but the relative growth rate decreased slightly at the 3rd and 5th day.However,there was no cytotoxicity.It was deduced that UMAO surface structure was beneficial to the initial adhesion of MC3T3-E1 cells,but excessive roughness resisted the MC3T3-E1 cell spreading.