| Ideal biocoatings applicated in orthopedics for correction of skeletal defects should be similar to the minerals of natural bones in chemical composition, crystallinity, morphology and crystallographic texture. Herein, we report, for the first time, the fabrication of hydroxyapatite(HA) coatings(HACs) with oriented arrangement by using bioglass coatings(BGCs, Ca O-Si O2-P2O5) as sacrificial tempaltes in a simulated body fluid(SBF) under hydrothermal conditions. The effect of reaction conditions on the morphology and oriented arrangement of HACs was studied by means of FESEM, TEM, EDS, XRD, FTIR and VSM. The formation mechanism of HACs with oriented arrangement has been investigated in detail. Siver nanoparticles(Ag NPs)-loaded HACs(Ag NPs-HACs) were prepared by silver mirror reaction, and the morphologies of HACs in the influence of silver load efficiency was further studied. SBF immersion test was used to investigate the in vitro bioactivity.The biocompatibility tests and osteoinductive tests by using human bone marrow stromal cells(h BMSCs) as cell models were used to investigate the in vitro biocompatibility and osteoinductive property of the HACs with different morphologies(net-plate: SHACs, oriented nanorod arrays: RHACs, oriented hexagonal nanoplate arrays: PHACs) before and after loaded with Ag NPs. Moreover, the antibacterial property was also studied by using Escherichia coli and Staphylococcus aureus as bacterium models.After soaking the BGCs in SBFA(normal SBF) for 12 h and in SBFC(with twice the concentration of P in SBFA) for 2 days under hydrothermal conditions, the elongated HA rods and HA hexagonal nanoplates deposit on the surfaces via a dissolution-precipitation reaction.With increasing the reaction time to 2 days, most of the HA rods are converted to HA blocky particles due to Ostwald ripening. The morphologies and oriented arrangement of HACs are easily determined by the kind of reaction mediums, reaction tempareture and Ca/P molar ration in SBF. If SBF is replaced by deionized water, the obtained coatings are rod-like HA with the poor crystal orientation. Within the appropriate hydrothermal reaction temperature range, the velocity of HA nucleus formation and nucleus growth as increasing as the tempareture increase. Moreover, increasing the hydrothermal reaction temperature can improve the oriented arrangement of HACs. If soaking the BGCs in SBFB(with twice the concentration of Ca in SBFA) for 12 h under hydrothermal conditions, the RHACs with longer HA rods and better orientation are obtained. The existence of magnetic Fe3O4 nanoparticles can affect the morphology and orientation of HACs via increasing the velocity of HA nucleus formation and decreasing the elocity of HA nucleus growth. If soaking the magnetic bioglass coatings(MBGCs, Ca O-Si O2-P2O5-Fe3O4) in SBFA for 24 h under hydrothermal conditions, the magnetic HACs(MHACs) with oriented nanorod arrays(RMHACs) are obtained, which have better orientation than RHACs. Moreover, the RMHACs possess much better hydrophilicity with a acontact angle of 10.8o than the RHACs with a contact angle of 15.3o because of the presencing of Fe3O4 nanoparticles.Ag NPs-HACs have been successfully fabricated via a silver mirror reaction, and the morphologies of HACs have significantly influence on the Ag NPs load efficiency. The loading of Ag NPs on the surfaces of SHACs, RHACs, PHACs are 1.90 wt%, 0.26 wt%, 1.53 wt%, respectively. Interestingly, the HA phase structure in coatings was not changed before and after silver mirror reaction.SBF immersion tests show that all of the RHACs and PHACs before and after loaded with Ag NPs exhibit great in vitro bioactivity. The RMHACs also exhibit great in vitro bioactivity, but the presencing of Fe3O4 nanoparticles decrease the deposit amount of plate-structure HA on the surfaces of RMHACs.The h BMSCs biocompatibility tests indicate that there are no obviously differences in biocompatibility of HACs before and after loaded with Ag NPs.The RHACs and PHACs as well as the Ag NPs-RHACs and Ag NPs-PHACs exhibit better in vitro biocompatibility than the SHACs and Ti-6Al-4V. Moreover, there are no obviously differences in biocompatibility bettween RHACs and PHACs before and after loaded with Ag NPs. Escherichia coli and Staphylococcus aureus antibacterial experiments show that the Ti-6Al-4V, SHACs, RHACs and PHACs have no antibacterial property, while the Ag NPs-SHACs, Ag NPs-RHACs and Ag NPs-PHACs have excellent antibacterial property.h BMSCs osteoinductive tests indicate that there are no obviously differences in osteoinductive property of HACs before and after loaded with Ag NPs. The RHACs and PHACs, Ag NPs-RHACs and Ag NPs-PHACs exhibit better osteoinductive property than SHACs and Ti-6Al-4V. However, there are no obviously differences in osteoinductive property bettween RHACs and PHACs, Ag NPs-RHACs and Ag NPs-PHACs. The excellent in vitro bioactivity, biocompatibility, antibacterial property, osteoinductive property of Ag NPs-RHACs and Ag NPs-PHACs suggest that they have great potential for bone inpalnts. |
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