Preparation, Antibacterial And Biocompatibility Study Of Zeolite Membrane Containing Silver On Titanium Alloy

As important member of inorganic microporous materials, zeolite has the special pore structure so that it has superior performance such as ion exchange, diffusion and adsorption, catalytic activity, etc. Therefore, zeolite has wide application in petrochemical, gas processing, fine chemicals, and other important national economic areas. With the development of research and application on zeolite, people also focus on the zeolite membrane and composite materials. Due to good biocompatibility, corrosion resistance and stability in biological environment, zeolites have been recently considered for medical use. For example, application of zeolites as a food supplement decreased the degree of certain radionuclides in the liver and kidneys. Owing to shape selectivity, zeolites have also been investigated as carriers for a variety of drugs. Therefore, there are potential applications of zeolite in the field of biotechnology.Orthopedic joint replacement surgery is one of the most significant medical achievements, patients'lesion joints are replaced with artificial joints in operation, which is continuing the physiological function and reducing the pain caused by the disease. Titanium is a good choice of artificial joint because of biocompatibility and mechanical property similar with human bone. To make the prosthesis implant effectively close to bone, its surface structure, material and other aspects are modified. Thus, artificial joint surface of titanium alloy is usually covered by porous material or other coating, which is beneficial to achieve good long-term bone ingrowth objective. However, after surgery bacteria in the wound easily gathered and bred on the artificial joint surface, which brought about postoperative infection on account of bacterial membrane. To solve this problem, we prepared zeolite membrane containing silver on titanium alloy surface, studied antibacterial and biocompatibility of the material, and comprehensively evaluated the potential application of the antibacterial silver zeolite membrane material.In situ hydrothermal synthesis, we prepared Na-A zeolite membrane on titanium alloy surface, through ion exchange process the inorganic antibacterial agent silver is introduced into the film. And the modulation of silver ion exchange can control the amount of silver content in membrane. X-ray diffraction proves the formation of zeolite film on titanium alloy surface is LTA-type crystal. It's clearly seen by SEM cubic crystals grow to dense film on the surface, and silver ions are exchanged into zeolite membrane with EDS. The bonding strength between membrane and titanium alloy through scratch test method is 25N. Angle test shows zeolite membrane whether containing silver or not is super hydrophilic surface. The research that zeolite membrane of silver ions release in simulated body fluid tells us the release behavior well fits the ion diffusion mathematical equation.Biological experiment makes study of the bio-toxicity and antibacterial activity among the titanium alloy, zeolite membrane and silver zeolite membrane. Toxicity test shows the material of titanium ally and zeolite membrane is toxic level of 0, silver zeolite membrane is grade I. In accordance with national standard, only grade 0 or I is allowed in vivo experiment. The results provide the next step basis in vivo. We study the antibacterial capacity of material surface and surrounding environment in antibacterial experiment of three different materials. Silver zeolite membrane and zeolite membrane both have surface antibacterial activity, including the silver zeolite membrane surface is more effective. And the hydrophilicity of the film contributes to antibacterial activity. In observation of the sterilization about three materials, we find only membrane containing silver has bactericidal activity to surrounding bacteria, which is related to the silver ion release.Through a series of zeolite membrane preparation, characterization and biological studies, we get good results of antibacterial activity and biocompatibility, which provide reference to in vivo experiment in future and are also meaningful to medical application on the implant surface.