Preparation of multifunctional drug sustained-release system by atomic layer deposition of ZnO in mesoporous titania coating

In previous studies, it has been proven that properties of titanium mesoporous (MP) coatings have a strong bond to substrates and excellent anti-stripping property, thus making it ideal for clinical implants. Also, the high porosity and specific surface area of MP material make it excellent for drug loading and sustained release. However, compared with untreated titanium, the bioactivity of MP samples does not have a significant improvement. In this study, we deposited zinc oxide (ZnO) into/on MP structures using atomic layer deposition (ALD) technology, which would significantly improve the biological activity of MP material while maintaining its structures. The fluorescence results showed that the porosity and drug loading capacity had little change after 10 ALD cycles (MP-ALD10), but decreased significantly after 30 ALD cycles (MP-ALD30). Cell results showed that with the increase of ALD cycle (from 0 to 50), the cytocompatibility of the corresponding materials increased first and then decreased: the optimal proliferation and differentiation of MC3T3-E1 cells were observed in MP-ALD10 and MP-ALD30 groups, respectively. Moreover, it was found that the antibacterial properties of different MP samples against Escherichia coll. and Staphylococcus aureus gradually enhanced with the increase of ZnO (MP < MP-ALD10 < MP-ALD30 < MP-ALD50). Overall, the study proved that 10 cycles of ZnO deposition significantly enhanced the bioactivity of MP without affecting its structure, drug-loading and drugreleasing properties, thus making MP-ALD10 more suitable for the development of drug-device combined titanium implants than MP.