Towards bio-safe and easily redispersible bare ZnO quantum dots engineered via organometallic wet-chemical processing
Małgorzata Wolska‐Pietkiewicz, Maria Jędrzejewska, Katarzyna Tokarska, Julia Wielgórska, M. Chudy, Justyna Grzonka, Janusz Lewiński
Abstract
Colloidal quantum dots (QDs) are of widespread importance for their unique combination of physicochemical properties and a number of prospective applications, and the search for efficient synthetic methods to produce readily dispersible, functionally stable and ligand-free quantum dot-based inks is a vital and timely area of research. We describe a convenient room-temperature and non-external-surfactant-assisted organometallic synthetic strategy for the reproducible preparation of solution-processable organic ligand-free zinc oxide (ZnO) QDs. The process involves the controlled transformation of a DMSO solution of commercially available diethylzinc upon exposition towards atmospheric air, where H2O and O2 act simultaneously as oxygen sources, and DMSO acts both as a solvent and a low-molecular-weight l-type surface protector. The resulting QDs with a narrow size distribution (4.7 ± 0.8 nm) were comprehensively characterized with a combination of various analytical techniques, which nicely documented their unique stabilities when dried, precipitated, re-dissolved or exposed to air. Moreover, to substantiate idealized surface passivation of the resulting QDs, we investigated their stability in the biological environment and nano-specific activity toward selected normal and cancer cell lines, and no significant toxic effect was revealed. Undoubtedly, the reported one-step-one-pot organometallic approach paves the way to high-quality and bio-stable ZnO QDs coated by an easily and reversibly removable organic shell, auguring applications in a vast array of devices and nanomedicine.