Chitosan-nanobioactive glass electrophoretic coatings with bone regenerative and drug delivering potential

Nanocomposites with bone-bioactivity and drug eluting capacity are considered as potentially valuable coating materials for metallic bone implants. Here, we developed composite coatings of chitosan (CH)-bioactive glass nanoparticles (BGn) via cathodic electrophoretic deposition (EPD). BGn 50-100 nm in size with aminated surface were suspended with CH molecules at different ratios (5-20 wt% BGn) in aqueous medium, and EPD was performed. Uniform coatings with thicknesses of a few to tens of micrometers were produced, which was controllable by the EPD parameters (voltage, pH and time). Thermogravimetric analysis revealed the quantity of BGn within the coatings that well corresponded to that initially incorporated. Apatite forming ability of the coatings, performed in simulated body fluid, was significantly improved by the addition of BGn. Degradation of the coatings increased with increasing BGn addition. Of note, the degradation profile was almost linear with time; degradation of 5-13 wt% during 1 week became 30-40 wt% after 7 weeks at almost a constant rate. The CH-BGn coatings showed favorable cell adhesion and growth, and stimulated osteogenic differentiation. Drug loading and release capacity of the CH-BGn coatings were performed using the ampicillin antibiotic as a model drug. Ampicillin, initially incorporated within the CH-BGn suspension, was eluted from the coatings continuously over 10-11 weeks, confirming long-term drug delivering capacity. Antibacterial tests also confirmed the effects of released ampicillin using agar diffusion assay against Streptococcus mutants. The CH-BGn may be potentially useful as a coating composition for metallic implants due to the excellent bone bioactivity and cell responses, as well as the capacity for long-term drug delivery.