An environmentally safe approach for the facile synthesis of anti-mutagenic fluorescent quantum dots: Property investigation and the development of novel antimicrobial applications

Abstract

Quantum dots as nanocrystals of semiconductor materials are synthesized with different methods. The green synthesis of fluorescent quantum dots using natural stabilizing agents has attracted much attention. This research aims to study the ability of Teucrium polium L. extract to green synthesize fluorescent silver quantum dots (AgQDs). The green synthesis of AgQDs was proved using UV–Visible spectrophotometer, Fourier Transform Infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX), Photoluminescence (PL) analysis, and Dynamic Light Scattering (DLS).According to the findings, the shape of fluorescent AgQDs was spherical, and the maximum abundance of particle size distribution was between 3 and 5 nm.Thereupon, antimicrobial, anti-mutagenicity, anticancer, and antioxidant activities were evaluated to distinguish the biological features of AgQDs. Gram-positive bacteria (S. epidermidis, MIC: 31.25 μg/ml) and fungi (C. albicans, MIC: 31.25 μg/ml) were the most susceptible to AgQDs. Moreover, the AgQDs solution had higher antimicrobial activity than AgNO3. The Ames test demonstrated that AgQDs have considerable anti-mutagenic activities (% mutagenicity inhibition greater than 40) and are not mutagenic. The anticancer activity of AgQDs was distinguished using MTT and brine shrimp lethality (BSL) assays. The analysis indicated that AgQDs had a strong potential for cytotoxicity (BSL: LC50 = 2.4 μg/ml, MTT: IC50 = 0.8 μg/ml). Further, AgQDs were used for bioimaging human ovarian OVCAR3 cells, and their biocompatibility was remarkable. In the DPPH assay, AgQDs displayed high antioxidant activity (89.9% inhibition). Using AgQDs to coat materials to develop antibacterial agents revealed significant activity against C. albicans and S. epidermidis strains. Our results indicate that T. polium is a promising source for synthesizing AgQDs. Due to the potent bioactivities of AgQDs, they can be used in medicine and industry.