A review on synthesis of quantum dots and their biomedical applications

Quantum Dots (QDs) are ultra-fine nanometer-sized semiconductor particles with a core-shell structure possess both electrical and optical properties. Their unique ability to emit pure, monochromatic light on being exposed to light makes them extremely versatile in their applications. The color of the light emitted directly depends on their size and shape. Smaller QDs emit shorter wavelengths, closer to the violet end of the visible light spectrum (~380-450 nm), while larger QDs emit longer wavelengths i.e in reddish spectrum (~620-750 nm).Owing to their “tunability”, QDs can be exploited in a wide range of fluorescent, photonic, and electrochemical applications. QDs represent elements mainly from Group II-VI (e.g., CdSe) or Group III-V (e.g., InP) with the resultant optical and electronic properties of the quantum dots being somewhere between bulk semiconductor material and individual atoms or molecules. Besides applications in energy and photonics, they are under extensive investigation and development for use in disease diagnosis and therapy, specifically in the area of controlled drug delivery, biosensing and imaging. This review surveys the progress of research explores their properties, synthesis, applications, delivery systems in biology, and their toxicity.