The nano-sized complexes usage in biomedical applications has grown significantly over the past ten years, nanoparticles are now a significant contributor to the advancement and revolution of medical applications. Particles with a size range of 1 to 100 nm exhibit novel and distinctive electrical, optical, photoresponsive, and catalytic capabilities, which may be the primary drivers driving this revolution. The radiolabelling of nanoparticles refers to the process of incorporating radioactive isotopes into nanoparticles. This technique enables the nanoparticles to be tracked, imaged and monitored using various imaging techniques, such as single-photon emission computed tomography (SPECT)/PET. Radiolabelling plays a crucial role in understanding the biodistribution, pharmacokinetics, and targeted delivery of nanoparticles in biological systems. In this study Selenium based nanoparticles (SeNPs) are explored for imaging and therapeutic potential as radio tracers due to their size, surface and kinetics, as well as their ability to be functionalized.

The ^99mTc radionuclide was used to radio labelled the naturally isolated selenium NP using conventional radio chemistry protocol. The radiolabeling yield was found 94.5±3% and analysed by various analytical tools. The synthesized ^99mTc-SeNPs was asses through in-vitro stability and their biodistribution was performed in-vivo over wistar rate at different time point. The investigation at post 6 hours revealed an accumulation that was mostly found in the liver and lungs (at 3.4% ID/g and 2.2% ID/g, respectively). These ^99mTc-SeNPs can be used for this property for imaging via SPECT.