Green Synthesis, Characterization and Applications of Quantum Dots

Abstract

Quantum dots (QDs) are crystalline nanostructures made up of 100–10,000 atoms (belonging to group II–IV of periodic table) having size ranging from 1.5 to 10 nm. Due to their ultra-small size of atoms, they not only exhibit exceptional electronic and luminescence properties, but also have shown a wide range of applicability in the field of biological sciences. There are a myriad of methods for the synthesis of QDs, but they are associated with the use of harmful and not cost-effective chemicals and hence have an unfavorable effect on living organisms and the environment. On the other hand, the natural synthesis of QDs is economical, sustainable and free from hazardous chemicals and materials required in the designing and manufacturing of these nanostructures. This way of synthesis of QDs involves the use of biological materials such as plants, bacteria and fungi. The literature revealed that several natural products such as flavonoids, alkaloids, terpenoids and quinines serve as reducing agents and could help in mediating their synthesis, whereas different microorganisms such as fungi and bacteria can also be employed for the formation of these nanostructures. Synthesized targeted QDs can be characterized by various methods including UV spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (PES). QDs are known for exhibiting diverse applications in biosensing, cell imaging, drug delivery, lasers, etc.