Incorporating CdTe nanocrystals into polystyrene microspheres: Towards robust fluorescent beads

The method for incorporation of the CdTe nanocrystals into polystyrene microspheres was described. The use of polystyrene for effectively enhancing the photostability of the Q-dots within the PS beads, was also analyzed. The photoluminescence (PL)investigations revealed that the PL efficiency of the CdTe dots was reduced by a factor of 1.7-2.0. It was observed that the fluorescence-quenching effects were mainly caused by free radicals and were strongly dependent on the presence of oxygen as well as the nature of the free radicals. The photobleaching experiments were performed by continuously illuminating the composite beads using ultraviolet light at 392nm. The results demonstrated that the composite beads simultaneously incorporating the two types of dots show an emission profile mainly determined by their input ratio.