Tellurium, the Forgotten Element: A Review of the Properties, Processes, and Biomedical Applications of the Bulk and Nanoscale Metalloid

Tellurium (Te) is a brittle, mildly toxic, and rare metalloid with an extremely low abundance in the planet. The element has been used in both its bulk and nanoscale forms for several applications in solar cell industry, semiconductors, catalysis, or heavy metal removal, among others. The end of the last century witnessed an explosion in new strategies for synthesizing different Te nanostructures with controlled compositions, sizes, morphologies, and properties, which allow these structures to enhance their impact in numerous applications. Nanomedicine has recently taken advantage of the metalloid in its nanoscale, showing promising applications as antibacterial, anticancer, and imaging agents. Nevertheless, the biological role of Te within living organisms remains mostly unknown, and just a few reports appear working on this matter. In this chapter, the forgotten elements are extensively studied in terms of its chemical, physical, and geological properties, and its main applications are summarized and studied for both bulk and nanosized tellurium. At the end, tellurium’s most important biomedical applications are presented with the aim to establish a general concept of the metalloid as a powerful biomedical tool with a bright future yet to be discovered.