Photoactive Antimicrobial CuZnO Nanocrystals

Semiconductor nanocrystals (NCs) are promising photocatalysts due to their high surface area to volume ratio and tunable physicochemical properties. Of particular interest are earth-abundant metal oxides, such as ZnO and CuO, which are stable under ambient conditions and in aqueous media and are environ-mentally and biologically compatible. While CuO NCs are efficient catalytic and antimicrobial materials featuring strong and broad absorption in the visible region, their challenging surface chemistry and low colloidal stability so far limited their wide implementation as photocatalysts. On the other hand, colloidal ZnO NCs function as excellent photocatalysts in various media, but their absorption is limited to the UV region. Herein, colloidal antimicrobial Cu1-xZnxO NCs are synthesized via a facile and cost-effective method, forming a unique spatial dependent structure and composition, with higher zinc concentration on the surface. The doped NCs show enhanced antimicrobial activity increasing with higher amount of dopant. Furthermore, the NCs exhibit superior antimicrobial activity upon visible light illumination effectively eradicating even multidrug resistant bacteria, due to increased ion migration and photocatalytic formation of reactive oxygen species. Such Cu1-xZnxO NCs, therefore, show promise as biocompatible antimicrobial materials that can be utilized under ambient conditions in diverse scenarios enabled by wet chemical processing.