DNA-functionalization of quantum dots is the attachment of strands of DNA to the surface of a quantum dot. Although quantum dots with cadmium (Cd) have some cytotoxic release, researchers have functionalized quantum dots for biocompatibility and bound them to DNA in order to combine the advantages of both materials. Quantum dots are commonly used for imaging biological systems in vitro and in vivo in animal studies due to their excellent optical properties when excited by light, while DNA has numerous bioengineering applications, including: genetic engineering, self-assembling nanostructures, protein binding, and biomarkers. The ability to visualize the chemical and biological processes of DNA allows feedback to optimize and learn about these small scale behaviors.[1][2]