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Nano Ag/ZnO-Incorporated Hydroxyapatite Composite Coatings: Highly Effective Infection Prevention and Excellent Osteointegration
journal contribution
posted on 2017-12-11, 00:00 authored by Yanzhe Zhang, Xiangmei Liu, Zhaoyang Li, Shengli Zhu, Xubo Yuan, Zhenduo Cui, Xianjin Yang, Paul K. Chu, Shuilin WuInterfacial
characteristics play an important role in infection prevention and
osteointegration of artificial bone implants. In this work, both Ag
nanoparticles (AgNPs) and ZnO NPs are incorporated into hydroxyapatite
(HA) nanopowders and deposited onto Ti6Al4V (Ti6) implants by laser
cladding. The composite coatings possess a hierarchical surface structure
with homogeneous distributions of Ag and ZnO. The Ag and ZnO NPs that
are immobilized by laser cladding ensure long-term and gradual release
of Ag and Zn ions at low cumulative concentrations of 36.2 and 56.4 μg/L
after immersion for 21 days. A large concentration of Ag released
initially increases the cytotoxicity but the large initial ZnO content
enhances the cell viability and osteogenetic ability. The nano Ag/ZnO-embedded
HA coating (Ag/ZnO/HA = 7:3:90 wt %, namely Ag7ZnO3HA) exhibits optimal
antibacterial efficacy and osteogenetic capability, as exemplified
by the broad spectrum antibacterial efficacy of 96.5 and 85.8% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively, together with enhanced
osteoinductivity with higher alkaline phosphatase (ALP) activity of
134.60 U/g protein compared to 70.79 U/g protein for the untreated
implants after culturing for 7 days. The rabbit femoral implant model
further confirms that the optimized composite coating accelerates
the formation of new bone tissues indicating 87.15% of the newly formed
bone area and osteointegration showing 83.75% of the bone–implant
contact area even in the presence of injected S. aureus. The laser-cladded Ag7ZnO3HA composite coatings are promising metallic
implants with excellent intrinsic antibacterial activity and osteointegration
ability.