Enhanced anti-breast cancer activity of green synthesized selenium nanoparticles by PEGylation: induction of apoptosis and potential anticancer drug delivery system

Breast cancer is a disease associated with high morbidity and mortality rates worldwide. The potential use of biogenic nanoparticles as alternative anticancer agents has been immensely acknowledged in several studies, particularly selenium nanoparticles (SeNPs). Nanoparticles were synthesised using the aqueous extract of Moringa peregrine (MPM-SeNPs) and were PEGylated (PEG-MPM-SeNPs). MPM-SeNPs were characterised by chemical and physical techniques. The successful capping of MPM-SeNPs with PEG was confirmed by spectrophotometric measurements and via Fourier-transform infrared spectroscopy (FT-IR) analysis. Furthermore, the effect of PEGylation of MPM-SeNPs on enhancing their anti-breast cancer activity and as a drug delivery agent was evaluated. Therefore, the loading efficiency and release of DOX at different pH values were measured; the antiproliferative activity of PEG-MPM-SeNPs against the adenocarcinoma breast cancer cell line (MDA-MB-231) was evaluated and compared with that of biogenic MPM-SeNPs and DOX-conjugated PEG-MPM-SeNPs. PEG-MPM-SeNPs and DOX-PEG-MPM-SeNPs had reduced IC50 values compared to MPM-SeNPs; IC50 of 11.54 ± 1.74 and 31.27 ± 2.9 μg mL−1 compared to 71.4 ± 3.4 μg mL−1, respectively. MPM-SeNPs and PEG-MPM-SeNPs caused apoptosis to MDA-MB-231 cells with a significant decrease in the mitochondrial membrane potential (MMP), increase in the released cytochrome C (Cyt C), and activation of caspase-3/9 (P < 0.05). Linking DOX to PEG-MPM-SeNPs led to an increase in caspase-3/8 concentrations and an increase in the released Cyt C, but there were non-significant differences in MMP (P > 0.1) between treated and untreated control cancer cells. MPM-SeNPs and PEG-MPM-SeNPs caused apoptotic reactions via an intrinsic pathway, while linking DOX to PEG-MPM-SeNPs caused apoptosis in cancer cells through an extrinsic pathway.