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

Abstract

: One of the important features influencing the biological applications of organoselenium compounds is their redox state, which in turn is affected by their interactions with nearby heteroatoms. To modulate the biological action of selenium in such compounds, researchers have designed new structural motifs and also developed new formulations using inorganic nanoparticles. Metal nanoparticles such as gold nanoparticles (GNPs) and magnetic nanoparticles (MNPs) like iron oxide (Fe 3 O 4 ) have been extensively studied for conjugation with many heteroatoms (sulphur, nitrogen and oxygen) containing ligands. Selenium, being more polarisable than sulphur, can induce significant surface passivation, thereby providing easy modulations with physico-chemical properties. Considering this, we investigated the physico-chemical properties of a few selenium compounds conjugated to GNPs and MNPs. The GNP conjugates were characterised by spectroscopic and microscopic tools, such as optical absorption, Raman spectroscopy, dynamic light scattering (DLS), the zeta potential and transmission electron microscopy (TEM). The results confirmed that the selenium atom was covalently conjugated to GNPs and this conjugation not only increased their electron transfer ability, but also their antioxidant ability. In another study, asymmetric phenyl selenides were conjugated with MNPs and characterised byX-ray diffraction (XRD), TEM, DLS and zeta potential. The radical scavenging ability of the selenium compounds improved upon conjugation with the MNPs. Therefore, the above studies confirmed that the redox activities of selenium compounds can be modulated upon conjugation with inorganic nanoparticles, such as GNPs and MNPs, which in turn provides new avenues for delivering organoselenium compounds.