A facile synthesis of hollow selenium nanoparticles (hSeNPs) was prepared using potato starch as a reducing and capping agent. The morphological and structural characters of the hSeNPs were characterised by ultraviolet‐visible spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X‐ray spectroscopy (EDX) and zeta potential analyser. The optical characteristics of hSeNPs were confirmed by UV. The presence of various functional groups in the hSeNPs suspension was confirmed by FTIR. The SEM results suggested that the synthesised hSeNPs were uniformly distributed and circular in shape with a hollow. The average size of the hSeNPs was found to be around 115 nm. The EDX analysis also confirmed the presence of hSeNPs in the sample. The zebrafish embryos were treated with hSeNPs of various concentrations ranging from 10 to 50 µg/ml. Abnormalities such as improper heartbeat, embryo sac oedema, ocular oedema and head oedema were noted at higher concentrations (30–50 µg/ml). A concentration‐dependent antioxidant activity of hSeNPs was observed. The hSeNPs showed good antibacterial activity against gram‐positive Bacillus subtilis and gram‐negative Escherichia coli . The results of this study indicate that potato extract reduces the toxicity of hSeNPs and lower concentrations of hSeNPs could be used for various biomedical applications in near future.

Selenium acts as an important element in the prevention and treatment of cardiovascular diseases but their health-related effects have not been fully explored. As a novel attempt, zebrafish embryos were treated separately with SeNPs (5–25 μg/ml) and sodium selenite (5–25 μg/ml) starting at early blastula stage. Abnormalities were also observed in the morphology of the zebrafish embryos. The SeNPs-treated embryos exhibited concentration-dependent increased in mortality, pericardial edema, and cardiac arrhythmia. In contrast, sodium selenite showed no significant malformation effect in developing zebrafish embryos. The results of the present study conclude that the SeNPs were more toxic than sodium selenite. The results also suggest that lower concentrations of SeNPs and sodium selenite can be used as possible therapeutic agents for cardiovascular-related problems.