Construction Of Photo-Inspired Graphene Oxide-based Antibacterial Coatings On The Surface Of Titanium Alloy

With the increase in people's demand for health and medical technology,coupled with a series of questions such as environmental pollution,aging of the population,and frequent accidental trauma,biomedical materials have been focused by people,and the number of demand for medical implants are getting larger.Among them,medical titanium and titanium alloys have been widely used in orthopedics and dental clinical treatment because of their good biocompatibility and excellent biomechanical properties.However,in the actual clinical application process,the surface of the implant will often suffer from bacterial infection after the operation,due to the lack of self-antibacterial properties.Once the bacterial infection occurs,it can lead to a series of extremely serious complications,often requiring surgery to remove the bacterial infection of the implant,causing more suffering and economic losses to the patient,and may even lead to amputation and endanger life.Of course,there are many measures have been adopted in clinical practice,injection and taking various antibiotics,modified implants to carry antibacterial agents,but these measures may lead to the emergence of drug-resistant bacteria,and cause more serious damage to the organism.what's more,these measures can not quickly kill infected bacteria.Namely,patients will go through a long and painful process.Reactive oxygen species(ROS)can kill bacteria quickly and efficiently.ROS generally require the photo-catalytic material to generate electron-hole pairs by photo-excitation and be trapped by surrounding oxygen.The 660 nm wavelength red light can penetrate the superficial skin tissue to the surface of the implant,stimulating the photocatalytic properties of the coating,thus achieving in situ sterilization.Based on the above issues,this paper will build a photo-inspired antibacterial coating based on graphene oxide(GO)on the surface of titanium implant.Under the excitation of visible light at 660 nm,it can achieve rapid and efficient in situ sterilization by generating ROS.It also does not damage the tissues around the implant.To explore the antibacterial efficiency and antibacterial mechanism of GO combined with different nanoparticles under the excitation of visible light at 660 nm,and to explore the synergistic bactericidal mechanism between coating photocatalytic antibacterial and nanoparticle physical sterilization.Specifically divided into the following three points:1.Preparation of different ratios of silver phosphate(Ag3PO4)/GO photocontrol antibacterial materialsFirstly,an aqueous solution of GO with appropriate concentrations was prepared by ultrasonication.Then,an appropriate amount of silver nitrate(AgNO3)was added under continuous stirring.The mixture solution was allowed to stand in vacuum for one day,so that the negatively charged GO in the aqueous solution could be fully combined with positively-charged silver ions.Next,the disodiIm hydrogen phosphate solution was added dropwise in AgNO3/GO mixture solution with vigorous stirring to prepare Ag3PO4/GO composites with different concentration ratios of Ag3PO4/GO.The test results show that the GO can be well combined with Ag3PO4 and also can change its bandgap.However,the degree of bandgap changed is related to the ratio of GO/Ag3PO4,when a certain percentage is reached,this mixed material can be inspired the excellent photocatalytic properties by the 660 nm visible light.2.Preparation of polydopamine(PDA)/different size of Ag3PO4/GO photocontrol antibacterial materials on the surface of titanium implantTitanium alloy have a porous surface with large surface area and many hydroxyl functional groups after alkaline heat treatment.The large surface area and rich hydroxyl groups of titanium alloy are extremely favorable to form a PDA coating with a sufficient thickness.The PDA coating,due to its unique properties,can easily and firmly graft GO/Ag3PO4 composites onto the surface of titanium alloys to form PDA/Ag3PO4/GO coatings,and the size of Ag3PO4 is different.The test results show that this kind of coating has very good photocatalytic antibacterial efficiency inspired by 660 nm visible light,moreover the synergistic of photocatalytic action and the innate antimicrobial ability of Ag3PO4 can achieve more excellent antibacterial effect,but this is related to the size of Ag3PO4.3.Construction of PDA/GO/AgNPs/Col photocontrol coating on titanium implant surface After the GO is fully absorbed the Ag+ in the solution,the Ag+ are reduced into silver nanoparticles(AgNPs)by ultraviolet light to obtain a GO/AgNPs composite solution,which is then grafted to titanium alloy.The titanium alloy which have experienced alkaline heat treatment and combined a layer of PDA.Then,the collagen was successfully grafted onto the surface of the titanium alloy by the oxygen-containing functional group of GO to form a covalent bond with collagen(Col),to form a PDA/GO/AgNPs/Col coating.The test results show that this coating can be inspired their excellent antibacterial properties by 660 nm visible light,achieve better results under the synergistic effects of photocatalytic and physical,and the collagen can greatly increase the biocompatibility of the coating and reduce cell damage.