Medically translatable quantum dots for biosensing and imaging

Photoluminescent quantum dots (QDs) promise many biomedical applications as a new class of optical probes showing unique optical properties such as high brightness, stability, and multiplexing ability. In this review, we focus on recent research interest of medically-translatable QDs for in vitro biomedical sensing and in vivo imaging. QD-based biomedical sensing shows higher selectivity and sensitivity over conventional methods for immunohistochemistry, immunoassay, and enzymatic assays. In addition, QD-based biosensors afford simple detections of multiple biomarkers. QD probes in the second near-infrared region (1000 ≤ λ ≤ 1700 nm) show the great potential for in vivo fluorescence imaging because of the suppressed light scattering and the capability for deep tissue penetration. The second near-infrared emitting QDs covered in this review include Ag2S, Ag2Se, Ag2Te, PbS, PbSe, InAs, Cd3P2, Cd6P7, and Cd3As2 QDs. In vivo imaging properties of these QDs are highlighted with special reference to vasculature imaging and tumor localization.