Hydroxyapatite/titanium dioxide/bioactive glass composites with anti-microbial performance under multiple illumination conditions

Hydroxyapatite/titanium dioxide/bioactive glass (HA/TiO 2 /BG) composites with different amount of BG, were synthesized to achieve anti-bacterial performance under multiple illumination conditions. Two types of bioactive glasses, 45S5 and S53P4, were employed based on their good anti-bacterial activity under white light. The HA/TiO 2 /BG composites were prepared via mechano-chemical technique, and their crystalline structures were confirmed using X-ray diffraction (XRD). Anti-bacterial activities of the HA/TiO 2 /BG composites were determined by bacteria viability, and photocatalytic activities were examined by decomposition of methylene blue (MB) solution under UV exposure. XRD patterns confirmed the formation of hydroxyapatite and anatase titanium dioxide without any other minor phases. HA/TiO 2 /BG composite of 20 wt% 45S5 showed superior anti-bacterial property against both E. coli and S. aureus , compared to that of S53P4, under 24 h exposure to white light and dark conditions. For photocatalytic activity, HA/TiO 2 /BG composites could reduce ~ 65% of methylene blue concentration after 24 h UV exposure. The HA/TiO 2 /BG-coated nonwovens were prepared and investigated for their anti-bacterial performances and photocatalytic activities. Morphological features of the HA/TiO 2 /BG-coated nonwovens, investigated under SEM, revealed that the composite particles deposited mainly in micro-spaces between fibres of the nonwovens. All coated nonwovens exhibited 99% anti-bacterial properties after 24 h exposure both under white light exposure and dark conditions. They also exhibited good photocatalytic activities such that MB reduction was about 90% after 24 h UV exposure. This study demonstrated that HA/TiO 2 /BG composites have high potential to be used for anti-bacterial filter application under multiple illumination conditions. Graphical abstract