Experimental Study On Antibacterial Mechanism Of Ti-Ag Alloy

Implantable medical devices often face problems such as corrosion failure,poor biocompatibility,and bacterial infection during work.The abuse of antibiotics,bacteria begin to develop drug resistance,so the most perfect way to inhibit bacteria is not to use antibiotics,but to use medical devices with antibacterial properties to avoid bacterial infections.At present,some antibacterial titanium alloys have been put into clinical use.There are two main different perspectives on the antibacterial mechanism of antibacterial Ti-Ag alloys.One believes that the alloy kills bacteria by contact,and the other is that metal ions kill bacteria.In order to explore its bactericidal mechanism,a novel antibacterial Ti-Ag alloy was prepared and SEM and XRD were used to characterize the microstructure of the alloy and to detect the existence of Ag in the alloy.The corrosion resistance and the ion elution amount of the alloy are detected by an electrochemical test and an ion elution test;The antibacterial properties of the alloy were tested by a film-coating antibacterial test.Further,the alloy is subjected to surface etching treatment,and then the hydrophilicity,surface roughness,corrosion resistance and ion elution amount are sequentially detected.The biocompatibility and cell 'adhesion of the alloy were examined by cck-8 experiments and cell adhesion experiments.Finally,the antibacterial mechanism of the alloy was reasonably inferred from the silver ion elution data and the silver ion antibacterial experiment results.The main findings of the experiment are as follows:In this thesis,Ti-Ag alloys with different silver content were prepared by smelting method,then solution treatment and aging treatment were carried out,and the microstructure of the alloy was observed by X-ray diffractometer and scanning electron microscope.The alloy treated at 400? has a small amount of fine Ti2Ag precipitated in the Ti-11 Ag alloy,and the other alloys have no second phase precipitated.The Ti-7Ag,Ti-9Ag and Ti-11Ag alloys aged at 600? precipitates a large amount of dispersed silver-containing second phase.At the same time,as the silver content of the alloy increases,the amount of precipitation of the second phase also increases.The corrosion resistance of Ti-Ag alloy in 0.9%NaCl solution was determined by electrochemical method.The results show that the corrosion resistance of Ti-Ag alloy is from low to high:Ti-3Ag<Ti-5Ag<Ti-7Ag<Ti-9Ag<Ti-11 Ag.The antibacterial experiment results show that the antibacterial properties of Ti-Ag alloy from low to high are:Ti-3Ag<Ti-5Ag<Ti-7Ag<Ti-9Ag<Ti-11Ag,but only Ti-7Ag,Ti-9Ag and Ti-11Ag alloy exhibits good antibacterial properties(antibacterial rate is greater than 50%).The results of cytotoxicity test showed that Ti-7Ag,Ti-9Ag and Ti-11Ag alloys were not cytotoxic and showed good biocompatibility.The corrosion resistance of Ti-Ag alloy in 0.9%NaCl solution was determined by electrochemical method.The results show that the corrosion resistance of Ti-Ag alloy is from low to high:Ti-3Ag<Ti-5Ag<Ti-7Ag<Ti-9Ag<Ti-11Ag.The antibacterial experiment results show that the antibacterial properties of Ti-Ag alloy from low to high are:Ti-3Ag<Ti-5Ag<Ti-7Ag<Ti-9Ag<Ti-11Ag.The results of cytotoxicity test showed that Ti-7Ag,Ti-9Ag and Ti-11Ag alloys were not cytotoxic and showed good biocompatibility.After surface etching,there was no significant difference in hydrophilicity and surface roughness of the alloy.The open circuit potential curve and self-corrosion curve of the alloy were measured by electrochemical method to test the corrosion resistance of the prepared samples.The results show that the order of corrosion resistance from weak to strong is:Ti-7Ag<Ti-9Ag<Ti-1lAg.The antibacterial properties of the alloys measured by antibacterial experiments were as follows:Ti-7Ag<Ti-9Ag<Ti-11Ag,and the antibacterial properties were significantly stronger than those before surface treatment.The cytotoxicity of the alloy after acid etching was further tested by CCK-8.The results showed that the Ti-7Ag,Ti-9Ag and Ti-11Ag alloys after acid etching were not cytotoxic..Comparing the silver ion elution data of the Ti-Ag alloy after acid etching treatment with the silver ion antibacterial experiment results,it can be seen that the amount of silver ion elution of the alloy before the surface treatment does not contribute to the antibacterial property.The silver ions eluted by the acid-etched Ti-Ag alloy partially contributed to the antibacterial properties of the alloy.At the same time,comparing the antibacterial properties of the alloy before and after the surface etching treatment,it can be seen that the antibacterial property of the acid-etched alloy is significantly stronger than that of the untreated alloy.Therefore,based on the above experimental results,it is inferred that the antibacterial property of the alloy plays a certain role in addition to the contribution of the second phase.