Application of medical antibacterial coating in implant infection

The population aging rate has increased the pressure of orthopedic medical treatment.
According to statistics, there are more than 5 million cases of fracture implants in China each year, and endophyte infection is one of the serious complications after surgery and is difficult to prevent.
Although doctors made various preparations to prevent bacterial contamination before the operation, postoperative infection still cannot be avoided.
In order to reduce the incidence of postoperative infections, in recent decades, people have made significant progress in aseptic technology, aseptic environment and preventive application of antibiotics during surgery.
Antibacterial endophyte materials have become an effective means to reduce postoperative infections.
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Due to medical needs, the surface of internal plants usually needs to have certain characteristics, but these can lead to the development of related infections on the surface of biological materials.
Therefore, it has become a research hotspot to modify the surface of endophytes to improve the antibacterial properties of the surface.

Antibacterial coating refers to the use of internal plant materials as the substrate, and various materials with antibacterial functions are coated on the substrate through processes such as spraying, sol-gel, composite plating, ion implantation, and magnetron sputtering.
As the antibacterial coating will gradually wear out with application and cannot maintain its long-term antibacterial effect, how to enhance the binding force of the antibacterial coating and the substrate and obtain good antibacterial, biocompatibility, high wear resistance, and durability It is the key issue of current research.

According to the coating composition, it can be divided into antibiotic coating, non-antibiotic organic antibacterial agent coating, inorganic antibacterial agent coating, anti-adhesion coating and antibacterial bioactive polymer coating.

Antimicrobial coating

Antibiotic coatings are the early research direction of antibacterial materials, which have the advantages of fast antibacterial effect, long duration, and low toxicity.
Common antibiotics due to antibacterial coatings include gentamicin, cephalosporin, minocycline, carbenicillin, amoxicillin, tobramycin and vancomycin, but they still face many problems in clinical applications : How to select antibiotics with strong bacterial sensitivity to load on the surface of the inner plant, how to make it have a longer effective antibiotic release time, how to prevent the concentration of antibiotics released from being lower than the minimum inhibitory concentration, etc.

Non-antibiotic organic antimicrobial agent coating

Compared with antibiotic antibacterial coatings, non-antibiotic organic antibacterial coatings have a lower risk of resistance (such as chlorhexidine, chloroxylenol, polyhexamethylene biguanide) and can be used in the body for a relatively longer cycle.
Similarly, non-antibiotic organic antibacterial agent coatings also need to consider suitable coating materials as carriers to meet the drug loading and release methods required in clinical applications.

Inorganic antibacterial agent coating

Inorganic antibacterial agent coatings have the advantages of strong antibacterial ability, good biocompatibility and stability, etc.
, and can be widely used in medical devices.
Inorganic antibacterial agent coatings include silver, copper, zinc, chlorine, fluorine, etc.

, which can be loaded by anodizing or plasma immersion, and rely on the released ions to destroy the bacterial cell membrane and inhibit the metabolism of antibacterial.
Silver is the most well-known among various inorganic fungicides, and has many antibacterial advantages: a wide range of antibacterial properties, low concentration of silver can inhibit Gram-positive/negative bacilli and certain drug-resistant bacteria; silver can inhibit the attachment of bacteria to The surface of the implant biological material does not affect the activity of bone cells and epithelial cells; the antibacterial effect of silver is relatively long and it is not easy to produce drug resistance; silver as a coating has good biocompatibility, no genetic or cytotoxicity; silver coating The layer is relatively stable and can be prepared by a variety of techniques; silver can be used as an additive to add a variety of biological materials to improve its performance; the antibacterial ability of silver can be enhanced by other conditions, etc.

Other inorganic antibacterial agents have not been widely used in medical treatment like silver because of their poor application effects and related adverse reactions.

Anti-adhesion coating

The anti-adhesion coating can change the number and reproduction of bacteria on the surface of the implant by changing the roughness, hydrophilicity, conductivity and other characteristics of the surface of the implant, so as to achieve the purpose of antibacterial.

Surface modified anti-adhesion coating is a relatively simple and economical way to eliminate bacterial adhesion through the surface properties of the implant, such as ultraviolet light irradiation treatment to improve the bone conduction and antibacterial properties of the titanium implant.
Experiments have proved that the surface modification of the implant can improve the antibacterial effect of the implant, which is also a new research direction of antibacterial coating.

Polymer coating

The polymer titanium alloy coating can significantly reduce the adhesion of Staphylococcus aureus and Staphylococcus epidermidis, has good antibacterial ability and improves biologically active molecules.
These coatings achieve antibacterial effects by blocking the adhesion of bacteria to internal plants and preventing the formation of biofilms.

Biologically active molecules, such as chitosan and hyaluronic acid, have anti-bacterial adhesion and bactericidal abilities.
Chitosan has biocompatibility, biodegradability, physiological inertness, antibacterial properties, antifungal properties and other properties.

It has a wide range of antibacterial properties and is used in artificial bone tissues, wound dressings, tissue engineering scaffolds, etc.

The polymer coating has high research value, but its mechanism and process in the body need to be further studied.

Conclusion

The emergence of biological material-related infection cases has made people realize the importance of antibacterial materials, and promoted the research and development of new antibacterial endophytes and antibacterial coatings.
At present, the focus is on antibacterial coatings with high-efficiency and controlled release capabilities.
However, due to antibacterial coatings It can only prevent early postoperative infection caused by surgical contamination.

The preparation of high-load antibacterial agent and long-term controlled release endophyte coating is one of the research directions of antibacterial coatings in the future, and it is of great significance for the prevention of biological material-related infections.