Decreased Staphylococcus epidermis adhesion and increased osteoblast functionality on antibiotic-loaded titania nanotubes.

Bacterial infection is one of the most common problems after orthopedic implant surgery. If not prevented, bacterial infection can result in serious and life threatening conditions such as osteomyelitis. Thus, in order to reduce chances of such serious complication, patients are often subjected to antibiotic drug therapy for 6-8 weeks after initial surgery. The antibiotics are systemically delivered either intravenously, intramuscularly or topically. Systemic antibiotic delivery entails certain drawbacks such as systemic toxicity and limited bioavailability. Further, in order for the drug to be effective at the site of implantation, high doses are required, which can result in undesired side effects in patients. Thus, local antibiotic therapy is the preferred way of administering drugs. To that end, we have developed titania nanotubular arrays for local delivery of antibiotics off-implant at the site of implantation. These nanotubes were fabricated on bulk titanium using anodization techniques. The fabrication strategies allow us to precisely control the nanotube length and diameter, thus enabling us to load different amounts of drugs and control the release rates. In this work we have fabricated titania nanotubes with 80 nm diameter and 400 nm length. We have loaded these tubes with 200, 400 and 600 microg of gentamicin. The gentamicin release kinetics from these nanotubes and its effect on Staphylococcus epidermis adhesion were investigated. Further, a preosteoblastic cell line called MC3T3-E1 was cultured on gentamicin-loaded nanotubes to evaluate the effect of nanoarchitecture on cell functionality. Our results indicate that we can effectively fill the nanotubes with the drug and the drug eluting nanotubes significantly reduce bacterial adhesion on the surface. Also, there is enhanced osteoblast differentiation on nanotubes filled with gentamicin.