**6. Potential applications**

The unique optical and electrical properties of the quantum dots make them favorable for multitasking purposes. These particles emit light in visible and near-infrared region. Quantum dots are applied in electronics devices such as single electron transistors or micro-LED array, in energy applications as solar cells, photovoltaic devices, or light-emitting diodes [15]. In addition, they are also used in biological and medical sciences for imaging, labeling, detecting, and sensing. Quantum dots synthesized in organic solvents are insoluble in water. However, functionalizing the quantum dots with either hydrophilic functional groups, ligands, or by capping, organic coating can be used to transform them to aqueous soluble quantum dots. In biological applications, DNA oligonucleotide, aptamer, or antibody are grafted on quantum dots through thiol, amine, or carboxyl groups giving cross linking with molecules. Functionalized quantum dots are used for cell targeting, cell labeling, and drug delivery and in imaging. The advantages of quantum dots with respect to organic dye molecules are their high brightness, stability, and quantum efficiency [16, 17].
