Recent advances in non-toxic quantum dots and their biomedical applications

Quantum dots (QDs) with unique quantum confinement effect and electro-optical properties are attractive for biomedical applications. Toxic effects of traditional semiconductor QDs made of heavy metal ions have serious safety concerns for their undesired environmental or healthy impact. Recent reports on core-shell structure modification of QDs by using biocompatible ligands or polymers is one way to be effectively minimizing toxicity effects of traditional QDs. Furthermore, designs of heave metal-free and metal-free QDs formulations are more promising alternatives, due to the non-toxic and eco-friendly nature of the starting materials. In article, we will review the recent designs of non-toxic or less toxic QDs, including carbon-based, biomolecules-based, silicon-based, and ternary I-III-VI QDs, and their biological applications (bio-imaging, drug delivery, gene therapy and immunoassay).