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

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