Quantum dots that absorb and emit near-infrared light waves are allowing researchers to look deeper into tissues than ever before because infrared light scatters less in the human body than other wavelengths, providing clearer images than conventional fluorescent imaging techniques.
Near-infrared quantum dots could be used for whole body imaging of animals, or to target specific tissues, such as tumors and lymph nodes, but some of the compounds used in their composition are proven to be toxic.
Quantum dots using cadmium and lead are particularly toxic to cells and tissues; these metals also pose a risk to the environment, and although some researchers have tried to reduce QD toxicity by using a special non-toxic shell, these protected quantum dots are not as effective for imaging as non-coated, non-toxic ones based on carbon, silicon or germanium, the reviewers note.
Silicon quantum dots in particular are promising because they are safe and very efficient at emitting light. Before those near-infrared quantum dots can deliver on their promise, both safety issues and more effective fabrications methods will be required to improve non-toxic QD efficiencies.
National Institute for Materials Science (NIMS) – www.nims.go.jp