**Abstract**

Quantum dots (QDs) are of prevalent scientific and technological consideration because of their tunable size and thus frequency change (band-gap energy) in the NIR optical region. QDs have exceptional properties such as optical, physiochemical, electrical, and capacity to be bound to biomolecules. These selective size-dependent attributes of QDs assist them with having versatile applications in optoelectronic and biomedical fields. Their capacity to emit light at various frequencies because of an outer stimulus makes quantum dots perfect for use in imaging, diagnostics, tests for individual particles, and medication transportation frameworks. Ongoing advances in quantum dot design incorporate the potential for these nanocrystals to become therapeutic agents to restore numerous disease conditions themselves via bioconjugation with antibodies or medications. In this chapter, a few advances in the field of biomedical applications, such as bio-sensing, bio-imaging, drug loading capacity, targeted drug delivery, anti-stacking limit hostile to bacterial activity, photo-thermal treatment, photodynamic treatment, and optical properties for biomedical applications are presented, further to a short conversation on difficulties; for example, the biodistribution and harmful toxic effects of quantum dots is also discussed.

**Keywords:** quantum dots, bio-sensing, bio-imaging, drug-delivery, anti-bacterial activity, photo-thermal therapy, photodynamic therapy, optoelectronic devices, functional QDs
