Novel Implant Coating Material Releases Antibiotics in Response to Bacterial Invasion

Artificial joints, often used to treat degenerative arthritis, create the challenge of bacterial infections. These infections can undermine the stability of the implant and lead to various complications, including those caused by antibiotic-resistant bacteria. These bacteria often trigger recurring infections even after antibiotic treatment, necessitating further procedures. Now, researchers have designed a functional implant coating material that promptly releases antibiotics in reaction to changes in the body's environment as a result of bacterial infection.

Developed by a collaborative research team comprising scientists from Pohang University of Science and Technology (POSTECH, Gyeongbuk, Korea), the coating is based on mussel adhesion proteins. Their research specifically focused on DOPA, an amino acid key to mussel adhesion. DOPA forms strong bonds with metal ions, particularly iron, but these bonds weaken when the acidity (pH) level drops. Given that bacterial invasion alters the body's pH, the team designed the coating that contains antibiotics under normal conditions, but releases them rapidly when infection-induced acidification occurs. It releases 70% of the antibiotics within eight hours, effectively eliminating the bacteria.

The material also exhibits remarkable durability, maintaining its antibacterial efficacy even during the four weeks of bone regeneration phase following an implant procedure. The amount of antibiotics released by the material matches the severity of the bacterial infection. The researchers validated the antibacterial efficacy of the coating material based on varying bacterial concentrations. Importantly, the bond between DOPA and iron ions proved highly resistant to external physical stimuli, making it resistant to abrasion and mechanical loads during the implantation process.

"The immediate and sustained antimicrobial effect of the adhesive implant coating material has the potential to significantly enhance the success rate of implant procedures," said Professor Hyung Joon Cha from POSTECH who led the study.

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