Over the years, biological imaging has seen many advances, allowing scientists to unfold many of the mysteries surrounding biological processes. The ideal imaging resolution would be in nanometres, as most biological processes occur at this scale. Nanotechnology has made this possible with functionalised nanoparticles that can bind to specific targets and trace processes at the cellular and molecular level. Quantum dots (QDs) or semiconductor nanocrystals are luminescent particles that have the potential to be the next generation fluorophores. This paper is an overview of the basics of QDs and their role as fluorescent probes for various biological imaging applications. Their potential clinical applications and the limitations that need to be overcome have also been discussed.

Water soluble, near infrared emitting type II/type I CdTe/CdSe/ZnSe quantum dots were synthesized in a simple one-pot procedure. The emission wavelength could be tuned from 530 nm (original CdTe core) to 670 nm and the particle size was determined by TEM measurement. The resulting quantum dots were used in subcutaneous deep tissue monitoring.