Photon induced quantum yield regeneration of cap-exchanged CdSe/CdS quantum rod for ratiometric biosensing and cellular imaging
Full water-dispersion of commercial hydrophobic CdSe/CdS core/shell quantum rods (QRs) were achieved by cap-exchange using a dihydrolipoic acid zwitterion ligand at a low ligand: QR molar ratio (LQMR) of 1000. However, this process almost completely quenched the QR fluorescence, greatly limiting its potential in downstream fluorescence based applications. Fortunately, we discovered that the QR fluorescence could be reinstalled by exposure to near ultra-violate to blue light radiations (e.g. 300-450 nm). These “reborn” QRs were found to be compact, bright, stable, and resisting non-specific adsorption, making them powerful fluorescence probes in broad biomedical applications. We demonstrated its potential in two model applications: first the QRs were conjugated with His8-tagged small antibody mimetic proteins (also known as Affimers) for sensitive detection of target proteins via a Förster resonance energy transfer (FRET) readout strategy. Second, the QR surface was functionalized with biotins for targeted imaging of cancer cells.