Photocatalytic Stealth Effect Of Titanium Dioxide And Its Application

Avoiding various types of undesirable host reactions after in vivo implantation by modulating the materials’surface physicochemical properties will help improve the overall biological performance of the implanted materials.In particular,it is of great relevance to developing simple strategies to achieve stealth effects on host reactions without introducing additional hydrophilic organic molecules.Inorganic materials are inevitably covered with a layer of indefinite carbon,and they are usually considered an inert organic contaminant that does not affect the protein adsorption behavior on the material surface.However,the authors suggest that the degree of enrichment of these organic contaminants on the material surface gives them the potential to be modified to produce bioactivity and thus modulate protein adsorption behavior.TiO₂ is a widely used biomaterial that also possesses photocatalytic properties.Recently researchers have gained insight into the types of organic pollutants adsorbed on TiO₂ surfaces and the alteration of the chemical state of these organic pollutants due to the photocatalytic effect.On the other hand,TiO₂ has been discovered one after another in recent years to possess antibacterial adhesion and anti-coagulation properties after receiving UV irradiation.However,there is no clear understanding of whether these biological functions are stealth effects and the relationship between these biological functions and the chemical states of organic contaminants on the TiO₂ surface.In this paper,our study shows that TiO₂ photocatalytic generation of reactive oxygen species（ROS）,most likely superoxide anion（O₂^-）and its derivatives,can oxidize organic pollutants to carbonyl-containing reactive residues.Furthermore,this carbonyl-containing layer gives TiO₂ the unique ability to immobilize autologous albumin from body fluids,which leads to a beneficial photocatalytic stealth effect that helps TiO₂ avoid adverse reactions including clotting,inflammation,and tissue proliferation.Thus,this photocatalytic stealth effect facilitates tissue repair of implanted devices,such as vascular scaffolds and subcutaneous implants,conferring excellent long-term biocompatibility of TiO₂.More importantly,we found that this photocatalytic stealth effect can be transferred to other inorganic materials by photocatalytic printing,which provides a basis for developing new surface modification methods.Furthermore,we found that this photocatalytic stealth effect can also be extended to materials such as silver nanoparticles near TiO₂,which provides a basis for preparing composite materials with antibacterial and photocatalytic stealth effects.Finally,we prepared TiO₂ micro-nano honeycomb structures with stealth effect with the help of the patterning technique.Through the combination of the photocatalytic stealth effect of TiO₂ and the capture-induction effect of the patterned surface,this photo-functionalized TiO₂ micro-nano honeycomb structure has excellent anti-platelet adhesion and anti-Staphylococcus aureus adhesion properties.Taken together,this thesis shows that the chemical state of organic contaminants may be a decisive factor in determining the adsorption behavior and biocompatibility of proteins on inorganic materials,which may be a new basis for the application,modification,and design of inorganic biomaterials,including but not limited to achieving stealth effects.