New insights into synthesis, morphological architectures and biomedical applications of elemental selenium nanostructures.

Selenium nanoparticles have shown to be versatile in its applications by being used in catalysis, solar cells, electronic devices and especially in medical applications as antiviral, anticancer, antitumor and antibacterial agents in different concentrations. It has also shown enhanced drug and gene delivery by conjugating with drug molecules and showing high synergistic effects. After realising its usefulness in biomedical field, we have made sincere effort to correlate and consolidate the recent developments made in its synthesis methods, structural features and their biological applications. This review paper highlights the three preparation methods, such as chemical, physical, and biological approaches. The variation in the different techniques employed for synthesis and the different parameters and process conditions dictating the size and morphology have been discussed. The importance and influence of various reducing agents used in chemical method, pulsed laser ablation technique in physical method and green plant extract, microorganism in biological approaches have been explored. The detailed structural features of both trigonal and hexagonal crystalline structures, with different nanoscaled morphologies such as nano spheres, rods, wires, tubes, and belts are also explored. An overview of its activity in various biomedical applications such as anticancer, antioxidant, antiviral, antibacterial, antifungal, antiparasitic, antihypersensitivity, and antidiabetics have been discussed.