Evaluation of biological properties of green-synthesized ZnSe quantum dots using microfluidic systems: A novel approach to enhancing antibacterial activity

Abstract

This study developed a green, eco-friendly, and rapid method for synthesizing zinc selenide quantum dots (ZnSe QDs) using the aqueous extract of Ficus johannis as a natural reducing and stabilizing agent. The extract was prepared through ultrasonic treatment at 40 °C for 15 min, enabling the synthesis of ZnSe QDs via the reaction between zinc nitrate and selenium dioxide. The ZnSe QDs were characterized using UV–Vis spectroscopy (absorption at ∼410 nm), fluorescence spectroscopy (emission at ∼473 nm), transmission electron microscopy (spherical morphology), and X-ray diffraction, (crystalline structure), confirming their spherical shape and average size of 6.9±1.2 nm. The synthesized ZnSe QDs demonstrated significant antibacterial activity, with minimum inhibitory concentration values of 0.8 mg/mL against Gram-positive B. subtilis and 1.6 mg/mL against Gram-negative Escherichia coli. Mechanistic studies revealed damage to bacterial membranes via potassium leakage and protein/nucleic acid release, supported by scanning electron microscopy observations of bacterial cell lysis. Using a microfluidic system further enhanced antibacterial efficacy, enabling faster and higher potassium leakage than conventional methods. Toxicity assays using Allium cepa bulbs revealed cytotoxic effects, suggesting the need for further research to mitigate toxicity for biomedical applications. Overall, this study showcases a green synthesis method with promising potential in nanomedicine.