Abstract
This study was purposed to examine the cytotoxicity and functions of biologically synthesised bismuth nanoparticles (Bi NPs) produced by Delftia sp. SFG on human colon adenocarcinoma cell line of HT-29. The structural properties of Bi NPs were investigated using transmission electron microscopy, energy dispersive X-ray, and X-ray diffraction techniques. The cytotoxic effects of Bi NPs were analysed using flow cytometry cell apoptosis while western blot analyses were applied to analyse the cleaved caspase-3 expression. Oxidative stress (OS) damage was determined using the measurement of the glutathione (GSH) and malondialdehyde (MDA) levels and antioxidant activity of superoxide dismutase (SOD) and catalase (CAT) levels. The half maximal inhibitory concentration (IC50) value of Bi NPs was measured to be 28.7 ± 1.4 µg/ml on HT-29 cell line. The viability of HT-29 represented a concentration-dependent pattern (5-80 µg/ml). The mode of Bi NPs induced apoptosis was found to be mainly related to late apoptosis or necrosis at IC50 concentration, without the effect on caspase-3 activities. Furthermore, Bi NPs reduced the GSH and increased the MDA levels and decreased the SOD and CAT activities. Taken together, biogenic Bi NPs induced cytotoxicity on HT-29 cell line through the activation of late apoptosis independent of caspase pathway and may enhance the OS biomarkers.