Investigations into the use of nano-based antimicrobial and osteoconductive coatings for bone implants.

Abstract

Objectives: Orthopaedic and dental implants are prone to frequent infections. This can lead to detrimental and often irreversible outcomes for many patients. The objective of this study was to develop a novel system using zinc oxide nanoparticles (nZnO) as a coating material that inhibits both bacterial adhesion / growth and promotes osteoblast growth. Methods and Results: Initially bacteria (S. aureus, E. coli, S. epidermidis and P. aeruginosa) were exposed to different concentrations of zinc oxide nanoparticulate suspensions (250 μg/mL, 500 μg/mL, 1000 μg/mL and 2500 μg/mL); with the higher concentrations of the suspensions demonstrating significant bactericidal effects. A novel electrohydrodynamic atomization coating technique (EHDA) was used to deposit mixtures of nZnO and nano-hydroxyapatite (nHA) onto the surface of glass samples (1 cm2). Exposure of the coated samples to phosphate buffered saline (PBS) and adult bovine serum (ABS) and measurement of bactericidal activity demonstrated superior antimicrobial activity for 100% and 75% nZnO composite coated samples. Lactate dehydrogenase (LDH) release from osteoblast-like cells (UMR-106 and MG-63) exposed to both nano-TiO2 and nano-ZnO nanoparticulate suspension supernatants indicated minimal toxicity. Nano-ZnO coated samples did not elicit LDH release with an increase in proliferation and viability of cells was observed. Scanning electron microscopy (SEM) and optical microscopy indicated that all cell types used (mesenchymal stem cells and osteoblast-like cells) were able to maintain their normal morphological state when adhered to the surface of the nano-coated material. Further studies as regards to patterned coated samples showed an exclusive adhesion selection by osteoblast-like cells to nZnO patterned regions that needs to be further investigated. Conclusion: ZnO NPs provide an antimicrobial and biocompatible coating material for medical and dental bone implants.