Studies On Interaction Mechanism Of Aunps And CdTe Qds

Energy transfer has been widely used in biological imaging, photovoltaic components and optical signal sensor, etc. In the traditional fluorescence resonance energy transfer(FRET) system, the energy donor and receptor are both organic molecules, which restricts the application of FRET in certain degree. In recent years, quantum dots possessed unique physical and chemical properties have replaced organic molecules as the new energy donor. Thus, the biosensor based on quantum dots arises at this moment. At the same time, gold nanoparticles(Au NPs) have also replaced organic molecular receptors as a kind of high efficient energy receptor. Therefore, quautum dot-Au NPs based FRET system has been paid more attention. As we all know, the energy transfer efficiency of FRET is affected by various factors, such as the size of the nanoparticles, morphology, and the distance between the donor and the receptor. However, few studies on the energy transfer mechanism of FRET system have been performed. So the emphasis of this work is the exploration of the FRET mechanism between Au NPs and CdTe quantum dots.In this paper, the FRET system was established with quantum dots as the energy donor and the different sizes of Au NPs as energy receptor, respectively. The interaction of Au NPs with quantum dots was studied using the spectral methods. The quenching constants and the efficiencies of the energy transfer for the FRET system were evaluated with the analysis of the fluorescence spectrum data. Moreover, the influence of Au NPs size on the energy transfer efficiency and the interaction mechanism of the system were discussed in detail. Additionally, with the chemical modification, the groups of NH2-DNA and SH-DNA were, respectively, connected to the surfaces of the CdTe quantum dots and Au NPs. Subsequently, the hybridization of two complementary DNA strands decreases the distance between the Au NPs and CdTe quantum dots, resulting in the fluorescence resonance energy transfer between the donors the acceptors. For the system of modified CdTe quantum dots and Au NPs, we determined the quenching constants and the energy transfer efficiencies according to fluorescence spectrum data and F?rster FRET theory. Furthermore, the influence of Au NPs size on the energy transfer efficiency and the interaction mechanism of the system were also discussed. The results show that the quenching constants for the system of modified donor and acceptor are greater than the system of unmodified donor and acceptor. Simultaneously, we found that the quenching efficiencies of the modified system first increase then decrease with the increasing sizes of Au NPs. While, the quenching efficiencies of the unmodified system increase with the increasing sizes of Au NPs, finally reach a platform. These results are theoretical significance in the development of Au NPs-CdTe QDs based biosensors.