Green synthesis and optimization of zinc oxide quantum dots using the Box–Behnken design, with anticancer activity against the MCF-7 cell line

Abstract

A green strategy and cost-effective approach was adapted to prepare Zinc oxide quantum dots (ZnO QDs) for biomedical applications. The prepared ZnO QDs may hold great promise as sensing scanners for diagnostics and therapy, as demonstrated in our current study. Zinc sulfate, Azadirachta indica, Aloe vera gel and Catharanthus roseus leaves extract were used to synthesize a novel natural Zinc oxide bionanocomposite (ZnO BC) and used as a precursor to prepare ZnO QDs by microwave-assisted technique. The ZnO BC was characterized by SEM–EDX, FT-IR, XRD, Zeta potential, and particle size analysis. The optical properties of QDs were investigated using UV and PL spectrophotometers. Experimental factors like the concentrations of ZnO Nps, C. roseus, and Aloe vera were evaluated using Box–Behnken design (BBD). MTT and hemolysis assay was performed using ZnO BC and ZnO QDs. Maximum absorbance was observed at optimized values of 0.5% ZnO Nps, 1 g A. vera gel, and 0.5 ml C. roseus leaf extract of ZnO QDs against BBD. There was a decreased viability rate, ranging from 60 to 15% for 0.5 mg/ml ZnO BC and 45 to 5% for 5 mg/ml ZnO QDs which revealed a tenfold decrease in cell viability with less concentration scale for 5 mg/ml of ZnO QDs when compared with that of 0.5 mg/ml ZnO BC. Also, the hemolysis test shows that the hemolysis ratio was below 0.5%, indicating non-hemolysis of ZnO QDs. Cellular morphology by results was supported by phase-contrast microscopy images. Good biocompatibility and high anticancer activity were noticed for ZnO QDs when compared to ZnO BC and provide versatile applications in the field of nano-biomedicine.Graphical abstract