NiTi-layered double hydroxide as an efficient photocatalytic fungicide of Aspergillus fumigatus spores: Capacity and mechanism

Eliminating dormant spores of Aspergillus fumigatus (A. fumigatus) with robust cell wall and super hydrophobicity is a formidable challenge and has attracted great attention. Herein, we found that NiTi-layered double hydroxide (NiTi-LDH) exhibited remarkable photocatalytic inactivation against A. fumigatus dormant spores (similar to 104 CFU/ mL), the killing rate could reach to 91.6% after 6 h visible light irradiation, which was reusable. Zeta potential test showed that NiTi-LDH possessed positively charged while spores presented negatively charged, which promoted their interaction through electrostatic adsorption, and this was also confirmed by SEM. It not only overcame the problems of low affinity caused by hydrophobicity, and short action distance of photo-generated active species because of their extremely short lifetime, but also weakened spore via interfering with its normal metabolism. In addition, NiTi-LDH exhibited wonderful visible light absorption and excellent photogenerated carrier's separation. Therefore, under the synergy of positive charge disruption and active species oxidation, the dormant spores were severely damaged and died. This work might provide enlightenment for selection and design of recyclable photocatalyst to efficiently and greenly remove pathogenic microorganisms under visible light.