Selenium oxyanions from harmful environmental pollutants to beneficial selenium nanoparticles

Selenium, in both organic and inorganic forms, is a necessary trace mineral for human nutrition, it is essential for proper function of the immune system and protect against cancer. Cancer, heart problems, infertility, thyroid conditions, and weakened immune systems are linked to insufficient selenium intake shortage. Selenium is distributed into different environmental compartments by natural and anthropogenic activities, and generally discharged in the form of selenate [SeO42−] and selenite [SeO32−], which are both toxic. Physical-chemical and biological treatment processes have been reported to exhibit good treatment efficiencies for Se from aqueous streams. Moreover, the possibility of the biotic transformation of highly soluble and toxic selenite to less toxic elemental selenium nanoparticles using various bacterial strains and their optimization is a promising and ecofriendly way for its removal from environment. Especially bacterial conversion is considered one of the best conversion methods for the synthesis of nanoparticles because of their quick growth rate, ease of handling, low cost, and high productivity. Also, selenium nanoparticles have generated interest in medicine as a medicinal agent with negligible side effects.In this review, the beneficial conversion of selenium oxyanions to selenium nanoparticles, their application in medical field, and various parameters of their biological optimization have been fully discussed and elaborated.