Metallic nanoparticles for theranostic application

Substances at the nanoscale, commonly known as “nanoparticles,” have always grabbed the attention of researchers for hundreds of years. They offer many advantages/benefits over larger particles such as increased surface-to-volume ratio and increased magnetic properties. Over the last few years, there has been a steadily growing interest in using transition metals–based nanomaterials in different biomedical applications such as targeted drug delivery, hyperthermia, photoablation therapy, bioimaging, and biosensors. The emerging interest is due to their excellent material properties such as chemical stability, nontoxicity, and biocompatibility. On the other hand, the lanthanide metals–doped luminescent nanoparticles have gained tremendous attention as one of the prime candidates for noninvasive biological applications due to their intriguing photophysical properties such as large Stokes shift, spectrally sharp emissions, long luminescence lifetimes (microsecond to the millisecond), and excellent photostability. Some lanthanide-doped luminescent materials also exhibit magnetic and light upconversion properties. Such nanomaterials have been used for a wide range of applications ranging from the detection of biomarkers, in vitro and in vivo imaging, to therapeutic applications. Recently, combined modalities of lanthanide nanomaterials for simultaneous detection/imaging and delivery of therapeutic agents, termed “theranostics” have been explored. In this chapter, we have discussed various theranostic agents from development through diagnosis to cure.