The Research On Inhibition Of Photobleaching And Blue Shift In Quantum Dots

As a new class of fluorescence probes, quantum dots have many excellent optical properties, compared with traditional fluorescence dyes, and played more and more important roles in the fields of molecular biology, cell biology, medicine, et al. This thesis studied the photobleaching, blue shift and their inhibition in commercial core/shell quantum dots. Briefly, the main works were as follows:1. The phenomenon of photobleaching and blue shift in quantum dots. Under continuous illumination, the photobleaching and blue shift of quantum dots adsorbed onto substrate in the field of view would arise. The photobleaching of quantum dots adsorbed or fixed through covalent bond at glass slide, and exposed in air, was investigated in detail. The results of experiment proved that the photobleaching of quantum dots would arise in solution, when the quantum dots in air showed high resistance to photobleaching. With the help of a transmission grating placed in front of the electron multiplying charge couple device, the blue shift of quantum dots was observed in solution; after the addition ofβ-Mercaptoethanol into the sample, the blue shift was suppressed. Research indicated that the photobleaching led to the disappearance of quantum dots in the field of view after the argumentation of relation between blue shift, photobleaching and disappearance of quantum dots in solution. We have investigated the photobleaching of quantum dots in different experimental conditions, observed the course of blue shift in quantum dots and found the inhibition of blue shift byβ-Mercaptoethanol, which will further the understanding of optical properties in quantum dots.2. Inhibition of photobleaching and blue shift in quantum dots by mercaptoethylamine. Experimental results demonstrated that the photobleaching, blue shift and blinking in quantum dots were effectively suppressed by an appropriate dose of mercaptoethylamine, and elucidated the possible mechanism behind this phenomenon after trying different reagents and quantum dots. The mercaptoethylamine is an electron donor and triplet quencher, it can suppresses the oxidation of quantum dots cores by donating electrons to block the blue shifting and eliminate the accumulation of the triplet excited states of quantum dots to impede the progress of photobleaching. The optical properties of quantum dots were improved by mercaptoethylamine, which would expand the application scope of quantum dots as fluorescent probes.