Surface immobilization of active vancomycin on calcium aluminum oxide

Implant and medical device infection is a significant and potentially deadly problem in biomaterials today. In order to mitigate this issue vancomycin was either adsorbed or covalently attached to the calcium aluminum oxide surface and tested for antibacterial activity. Covalent attachment was accomplished by a three-step solution immobilization method utilizing the hydroxyl groups on the calcium aluminum oxide surface. The three-step covalent antibiotic attachment method is applicable to any surface that contains hydroxyl and μ-oxo groups. Antibacterial activity of the immobilized antibiotics was evaluated by incubating the unmodified oxide and modified samples in a liquid Staphylococcus aureus bacterial solution. Growth of the bacteria was determined by optical density. Additionally, bacterial growth was evaluated in a zone inhibition assay. It was found that unmodified samples, vancomycin adsorbed, and vancomycin linked to the surface inhibited bacterial growth in liquid culture. Vancomycin linked or adsorbed to the surface produced zones of inhibition equal to that of the control antibiotic disk indicating it is as active on the surface as the native antibiotic. These samples can be autoclaved for sterilization and retain bioactivity. This is the first report of an attachment method for antibiotics on oxide surfaces that uses mild conditions.