Nanoparticle Conjugates of Selenium Compounds: Preparation, Characterisation and Electron Transfer Reactions

Organoselenium compounds find many applications in biology, medicine and material science. One of the important features of selenium influencing the biological application is its redox state, which in turn is affected by its interactions with nearby heteroatoms. To modulate the biological action of selenium, researchers have designed new structural motifs and also developed new formulations using inorganic nanoparticles. Metal nanoparticles like gold nanoparticles (GNP) have been extensively studied for conjugation with many heteroatoms (sulphur, nitrogen, oxygen) containing ligands. Selenium being more polarisable than sulphur can induce significant surface passivation thereby providing easy modulations in physico-chemical properties. With this aim, we investigated the physico-chemical properties of a few selenium compounds conjugated to GNP and iron oxide (Fe₃O₄) based magnetic nanoparticles (MNP) Two water soluble selenium compounds (an aliphatic selenide and a selenolane ) were conjugated with GNP and characterised by spectroscopic and microscopic tools like optical absorption, Raman spectroscopy, DLS, Zeta potential and TEM. The results confirmed that the selenium atom was covalently conjugated to GNP and this conjugation has not only increased their electron transfer ability but also their antioxidant ability. In another study two asymmetric phenyl selenides were conjugated with MNP and characterised by XRD, TEM, DLS and zeta-potential. The radical scavenging ability of the selenium compound improved on conjugation with the MNPs. Thus, the above studies confirmed that the redox activities of selenium compounds can be modulated on conjugating with inorganic nanoparticles like GNP and MNP, which in turn provide new avenues for delivering organoselenium compounds.