Fabrication of hydrophilic luminescent zinc oxide quantum dots for selective detection of copper ions and efficient inhibition of harmful fungi

Abstract

In this study, we have successfully prepared surface modified zinc oxide quantum dots (M-ZnO QDs) with ultra-stable fluorescence and excellent hydrophilicity through introducing (3-aminopropyl)triethoxysilane (APTES). The as-prepared M-ZnO QDs under the optimum condition presented strong yellow fluorescence emission under 355 nm excitation and showed satisfied reproducibility. Physical and chemical properties of the synthesized ZnO QDs were further studied by various characterization techniques. Transmission electron microscopy showed homogeneous distribution of spherical M-ZnO QDs with the average particle size of 4.03 nm. According to the characteristic that metal ions can quench fluorescence, M-ZnO QDs-based fluorescence sensor for the detection of Cu 2+ in aqueous solution is developed in this work, which has the advantages of excellent selectivity, good sensitivity and a wide linear range. The limit of detection was 0.51 μM and the linear detection range was 1–200 μM for Cu 2+ determination. The practicability of the fluorescent probe is further validated in the lake water and the satisfactory spiked recoveries of Cu 2+ ranges from 99.1 % to 108.8 %. Besides, M-ZnO QDs displayed concentration inhibition effect and strain effect on the growth of fungi. Thus, the as-prepared M-ZnO QDs are demonstrated to be promising for Cu 2+ determination and anti-fungal applications.