Bandgap Tunable AgInS based Quantum Dots for High Contrast Cell Imaging with Enhanced Photodynamic and Antifungal Applications

Abstract

Herein, we report a facile microwave-assisted synthesis of cadmium-free water-soluble silver indium sulfide (AgInS2 or AIS) and AgInS@ZnS (or AIS@ZnS) core-shell quantum dots (QDs) using glutathione (GSH) as stabilizer. The core and core-shell nanocrystals exhibit tunable bandgap ranging of 2.3–3.1 and 2.4–3.5 eV, mean particle size of 2.5 and 3.25 nm, quantum yield of 26% and 49%, and fluorescence lifetimes of 326 and 438 ns, respectively. The core-shell QDs exhibit color-tunable emission in the visible region (500 to 600 nm), where the tunability was achieved by varying the molar ratio of Ag:In in the precursors. In vitro evaluation of antifungal activity of these water/ buffer stable QDs against the fungal pathogen, Candida albicans demonstrated that these were not toxic to the fungal cells upto a concentration of 100 µg/ml for 16 hours of incubation. Confocal imaging and spectrofluorometric studies showed enhanced fluorescence inside the microbial cells suggesting that AIS@ZnS particles had the capability to easily penetrate the cells. The increased generation of reactive oxygen species was evaluated for the core-shell QDs (photosensitizers) by using 9, 10-anthracenediyl-bis(methylene)dimalonic acid (ABMDMA) as singlet oxygen (1O2) scavenger molecule. These QDs have the potential for use as high contrast cell imaging, photodynamic and antifungal agents.

Aqueous Synthesis of DNA-Functionalized Near-Infrared AgInS2/ZnS Core/Shell Quantum Dots

“…2e). As most of the ternary QDs, the decay curves were fitted by a multi-exponential function [40][41][42][43][44][45] . For both cQDs, the decay curve displays a triple exponential model considering the chi-square values (χ²) and the accurate fit in the short time ( Fig.…”

“…Although the seed-mediated growth route has led to larger, close-tostoichiometric, orthorhombic particles of lower size distribution, the chalcopyrite-type QDs resulting from the classical fast hot-injection route exhibit a significantly higher PLQY of (36 % vs. 8 %) with a longer lifetime exceeding 900 ns which are beneficial for bio-applications. 47,48 as well as the injection of ZnS precursors either at room temperature 38,49 or at higher temperature in heat-up, 19 microwave radiation assisted, 45,50 and hydrothermal 38,51 approaches. In contrast, here the ZnS shell was obtained through the simultaneous, dropwise addition of two distinct precursor solutions, one for zinc and one for sulfur, to the AIS cQDs at elevated temperature (96 °C).…”

Anticancer Photodynamic Therapy Properties of Sulfur‐Doped Graphene Quantum Dot and Methylene Blue Preparations in MCF‐7 Breast Cancer Cell Culture

“…We found previously that light exposure of the 1:1 GQD:MB preparation produced enhanced SO production compared to either MB or GQD alone in PBS . Most measurements of SO production are performed in nonbiological systems using the conversion of chemical substrates, for example 9,10‐anthracenediyl‐bis(methylene) dimalonic acid , and may not be representative of conditions present within cellular systems. In this study, we used the fluorescent dye, singlet oxygen sensor green (SOSG) , to monitor SO production in MCF‐7 cells.…”

Eco-friendly synthesis of CuInS2 and CuInS2@ZnS quantum dots and their effect on enzyme activity of lysozyme

“…Rather a fraction of Zn 2+ ions diffused into the nanocrystal structure of CIS, thus, widening and distorting it. 16 Therefore, a notable right shi in the peak positions of the CIS QDs was observed arising from shelling with ZnS because of the diffusion of Zn 2+ ions into the copper-indium lattice. 17 This shi towards the higher 2q values suggested the decrease in lattice parameters due to the smaller ionic radius of Zn 2+ relative to those of Cu + and In 3+ .…”