Research Progress of Active-passive Antibacterial Modification of Titanium Alloy Surface

Titanium alloy materials have good corrosion resistance, fatigue resistance and biocompatibility, and are widely used in the medical field, especially in implantable devices. Medical equipment has a variety of models, complex structures and small local dimensions. When exposed to various media during use, they are easy to attach stains, causing microbial aggregation and equipment infection. At present, in clinical practice, implant infection can only be treated through revision surgery, which not only generates expensive medical costs, but also brings great pain to patients. Therefore, safe and reliable medical equipment is the key to improve treatment efficiency. Based on this, starting from the growth mechanism of bacteria, the research status of antibacterial surface modification of titanium alloy medical devices was introduced, the research progress of preparing surface materials with good antibacterial activity was discussed, and the basic principles of two existing antibacterial surface modification methods were summarized, namely, active antibacterial surface modification methods that could directly kill contact bacteria and passive antibacterial surface modification methods that could resist bacterial adhesion. The surface modification methods of active sterilization can be divided into contact type and release type. Antimicrobial peptides (AMP), quaternary ammonium compounds (QACs) and chlorhexidine (CHX) belong to contact bactericides. Their bactericidal effect is mainly because the cations they carry can combine with the lipids in the bacterial cell membrane, destroy the bacterial cell membrane structure, and affect the permeability of the cell membrane. Antibiotics and inorganic metal nanoparticles are release bactericides, which can continuously release bactericides to the surrounding environment. These substances can further destroy the internal structure of bacteria after entering the bacterial cells. The passive surface modification method is to control the surface wettability and construct super hydrophobic or super hydrophilic surfaces, both of which have been proved to reduce the adhesion of bacteria on the surface. Super hydrophilic surface is usually modified by hydrophilic polymer materials, such as hydrogel, polyethylene glycol (PEG) and zwitterionic polymer. Their high surface energy enables them to closely combine with water molecules in the environment to form an interface hydration layer to further resist bacterial adhesion. However, the stability of these hydrophilic polymers is poor, and they are easy to decompose and fail in complex working environment. The surface with bionic super hydrophobic structure can reduce the contact between substrate and bacterial solution through the air layer trapped in its microstructure, so as to reduce the bacterial adhesion rate. Although the surface modified by active methods can fundamentally kill bacteria, in practical applications, these bactericides have caused problems such as bacterial resistance, high cost, biological toxicity and hemolysis. Passive surface modification does not prevent bacterial adhesion. Once adhesion occurs, the ability to resist bacteria will be lost. In order to overcome the limitations of a single method, it is necessary to design a surface antibacterial modification method with bactericidal and anti-adhesive effects to achieve efficient, long-term and safe cleaning of the surface of medical devices. The researchers have proposed an active-passive synergistic antibacterial modification method. The combination of chemical sterilization and structural bacteriostasis, giving full play to the advantages of the two methods, is the focus of future research. © 2024 Chongqing Wujiu Periodicals Press. All rights reserved.