Preparation of CaO-SiO2-CuO bioactive glasses-embedded anodic alumina with improved biological activities

Abstract To improve bone cell cytocompatibility properties of porous anodic alumina (PAA) and implement anti-bacterial properties, amorphous CaO-SiO2-CuO materials were loaded into PAA nano-pores (termed CaO-SiO2- CuO/PAA) by a facile ultrasonic-assisted sol-dipping strategy. The surface features and chemistry of the obtained CaO-SiO2-CuO/PAA were investigated by a field emission scanning microscope (FESEM), an energy-dispersive Xray spectrometer (EDS) and an X-ray photoelectron spectroscopy (XPS). The ability of the CaO-SiO2-CuO/PAA specimens to form apatite via a bio-mineralization processwas evaluated by soaking them in simulated body fluid (SBF) in vitro. The surface microstructure and chemical properties after soaking in SBFwere characterized. The release of ions into the SBF was also measured. In addition, rat osteoblasts and two types of bacterial were cultured on the samples to determine their cytocompatibility and antibacterial properties. The results showed that the amorphous CaO-SiO2-CuO materials were successfully decorated into PAA nano-pores and at the same time maintained their nano-featured surfaces. The CaO-SiO2-CuO/PAA samples induced apatite-mineralization in SBF. Meanwhile, the CaO-SiO2-CuO/PAA samples demonstrated great potential for promoting the proliferation of osteoblasts and inhibiting Escherichia coli (E. coli) as well as Staphylococcus. aureus (S. aureus) growth. Specifically, there was an 86.5±4.1% reduction in E. coli, an 88.0 ± 2.2% reduction in S. aureus for the CaO-SiO2-CuO/PAA surfaces compared to PAA controls. The capability to promote osteoblast proliferation and better antibacterial activity of CaO-SiO2- CuO/PAA may be attributed to the fact that Cu ions can be slowly and constantly released from the samples. Importantly, this was achieved without the use of antibiotics or any pharmaceutical agent. Ultimately, these results suggest that the CaO-SiO2-CuO/PAA substrates possessed improved bone cell cytocompatibility and high antibacterial properties leading to a promising bioactive coating candidate for enhanced orthopedic applications.