Evaluation of osteogenic and antibacterial properties of strontium/silver‐containing porous TiO₂ coatings prepared by micro‐arc oxidation

Abstract

Ti and Ti alloys are bioinert materials and two frequent problems associated with them are bacterial infection and lack of osteogenic potential for rapid bone integration. To overcome the problems, the present study incorporated strontium (Sr) and silver (Ag) simultaneously into porous TiO2 coatings through a single‐step technique, micro‐arc oxidation (MAO). Incorporation of Sr and Ag brought no significant changes to coating micromorphology and physicochemical properties, but endowed TiO2 coatings with both strong antibacterial activity and osteogenic ability. Antibacterial activity increased with Ag contents in the coatings. When Ag content reached 0.58 wt%, the coating showed both excellent short‐term (100.0%) and long‐term (77.6%) antibacterial activities. Sr/Ag‐containing coatings with 18.23 wt% Sr and 0.58 wt% Ag also presented good cytocompatibility for preosteoblast adhesion and proliferation, and promoted preosteoblast osteogenic differentiation both short‐termly and long‐termly. However, higher Ag content (1.29 wt%) showed toxic effects to preosteoblasts. In summary, MAO is a simple and effective way to incorporate Sr and Ag into porous TiO2 coatings and Sr/Ag‐containing TiO2 coating with 18.5 wt% Sr and 0.58 wt% Ag has both good osteogenic activity and strong antibacterial capability short‐termly and long‐termly. Therefore, such coatings are valuable for clinical application to strengthen osseointegration and long‐term high quality use of titanum implants.

Antibacterial and Osteogenic Properties of Ag Nanoparticles and Ag/TiO2 Nanostructures Prepared by Atomic Layer Deposition

“…Sengstock et al have found that Ag NPs mitigate the osteogenic differentiation of human MSCs even at nontoxic concentrations, without affecting chondrogenesis [ 38 ]. The incorporation of Ag in TiO 2 coatings exhibited negative effects on early MC3T3-E1 preosteoblast adhesion (within 2 h), mainly due to the toxicity of Ag ions [ 39 ]. However, cell differentiation according to ALP activity was relatively high.…”

“…Such a dramatic difference in the results can be explained by the significant influence of the silver concentration on the cytological response [ 42 ]. Recently, it has been established that the adherence and viability of the MG-63 and MC3T3-E1 cell differentiation are very sensitive to changes in Ag ion concentration [ 39 ].…”

Osteogenic capability of strontium and icariin-loaded TiO2 nanotube coatings in vitro and in osteoporotic rats

“…Such results are consistent with those previously reported. 17 , 27 The osteogenic effect of Sr may be due to its release from coatings, which lasted for 30 days, as demonstrated by the release test.…”

“…Sr 2+ ion release from the TiO 2 + Sr and TiO 2 + Sr + ICA groups was measured with a method described previously. 17 Briefly, the specimens were immersed in 5 mL phosphate buffer saline (PBS) at pH = 7.4 and incubated at 37°C in a dark environment with gentle stirring for 1, 3, 7, 30 and 120 days. At each time point, the PBS solution was replaced with new PBS and the collected solution was measured with an inductively coupled plasma emission spectrometer (ICP-AES, ICAP 6300, Thermo Fisher Scientific Co) to determine the Sr 2+ level.…”

“…MC3T3-E1 cells were cultured on different coatings as mentioned above for four and seven days, after which alkaline phosphatase (ALP) activity was evaluated as described previously. 17 Briefly, the cells were lysed in 1% Triton X-100 and centrifuged at 10 4 r/min for 5 min to obtain supernatants. The ALP protein concentration was determined by measuring the absorption value of the supernatant at 520 nm using a spectrum microplate reader (Yongchuang Medical Equipment Co., Ltd., Shanghai, China).…”