Quantum dots (QDs) are semiconductornanoparticles with a size less than 10 nm.[1][2][3] They exhibited size-dependent properties especially in the optical absorption and the photoluminescence (PL). Typically, the fluorescence emission peak of the QDs can be tuned by changing their diameters. So far, QDs were consisted of different group elements such as CdTe, CdSe, CdS in the II-VI category, InP or InAs in the III-V category, CuInS2 or AgInS2
in the I–III–VI2 category, and PbSe/PbS in the IV-VI category. These QDs are promising candidates as fluorescent labels in various biological applications such as bioimaging, biosensing and drug delivery.
However, most of the QDs in the commercial market are cadmium (Cd)-based QDs. Their potential toxicity in the biological environment has been debated over the past decade as the Cd2+ ions released from the QD surface are highly toxic to the cells and tissues.[4][5] Thus, many researchers have focused on the development of cadmium-free quantum dots (CFQDs) in the 2010s.[6][7][8]
^Oh, E.; Liu, R.; Nel, A.; Gemill, K. B; Bilal, M.; Cohen, Y.; Medintz, I. L. (2016). "Meta-analysis of cellular toxicity for cadmium-containing quantum dots". Nature Nanotechnology. 11 (5): 479–86. Bibcode:2016NatNa..11..479O. doi:10.1038/nnano.2015.338. PMID26925827.
^Xu, G.; Zeng, S.; Zhang, B.; Swihart, M. T; Yong, K. T; Prasad, P. N (2016). "New Generation Cadmium-Free Quantum Dots for Biophotonics and Nanomedicine". Chemical Reviews. 116 (19): 12234–12327. doi:10.1021/acs.chemrev.6b00290. hdl:10220/41591. PMID27657177.