| In recent years, quantum dots have attracted intensive interest due to its special optical and electronic property. Modification of quantum dots with organic dyes is found to enhance its photophsical propertiy, and the organic-inorganic nanohybrid assembles give rise to their potential applicaton in efficient light energy conversation systems, optical devices, biological sensing and imaging. The constructure of the organic-inorganic nanohybrid clusters is need to understanding of the interaction between dyes and quantum dots, the adsorption pattern of dyes on the surface of quantum dots at the molecular level. However, little investigation on the adsorption behavior of dyes molecules on the surface of nanoparticles has been done. In this paper, mono-6-thio-β-CD capped CdTe QDs was synthesized and its interaction with netrual red, methylene blue, methylene green, malachite green and crystal violet were studied with fluorescence, UV-absorption and resonance Rayleigh scattering spectra at molecular level. At the same time, the reaction mechanism was discussed and the reaction model was proposed combining with the transimission electron microscope and quantum chemical calculate method. Based on it, the fluorescence of mono-6-thio-β-CD capped CdTe QDs was modulated reversiblely. The main inverstigation of systems are as follows:1. The synthesis of mono-6-thio-β-cyclodextrin capped CdTe QDs and its interaction with neutral redThis paper presents a novel method for the synthesis of CdTe quantum dots (QDs) capped with P-cyclodextrin in aqueous solution using both TGA and mono-6-thio-β-CD) as stabilizer. Mono-6-thio-β-CD capped CdTe QDs with narrow size distribution and high photoluminescence quantum yield up to 81.3% was obtained by optimizing the synthesis conditions, such as the molar ratio of mono-6-thio-β-CD to thioglycolic acid (TGA) and refluxing time. Additionally, the interaction between mono-6-thio-β-CD-CdTe QDs and neutral red (NR) was studied with fluorescence, UV-absorption and resonance Rayleigh scattering spectrum. At the same time, the reaction mechanism was discussed and the reaction model was proposed through comparing with the interaction between TGA-CdTe QDs (which was synthesized using TGA as stabilizer singly) and NR and combining with transmission electron microscope (TEM) technology. In pH 6.1 BR buffer solution, the neutral red cationic form (HNR+) and neutral form (NR) combined with-SCH2COO-and mono-6-thio-β-CD on the surface of mono-6-thio-β-CD-CdTe QDs, respectively, and then reached to saturation when the concentration of neutral red was 7.5×10-6 mol/L. When its concentration was over 7.5×10-6 mol/L, the neutral red began to aggregate on the surface of mono-6-thio-β-CD-CdTe QDs, which resulted in mono-6-thio-β-CD-CdTe QDs particle-size increased, the fluorescence quenched sharply and the intensity of RRS increased markedly.2. The interaction of mono-6-thio-β-cyclodextrin capped CdTe QDs with methylene blue and methylene green, and its fluorescence regulated reversiblyCdTe quantum dots (QDs) capped withβ-cyclodextrin was synthetized using both TGA and mono-6-thio-β-CD) as stabilizer. The interaction of mono-6-thio-β-CD-CdTe QDs with methylene blue (MB) and methylene green (MG) was studied with fluorescence, UV-absorption and resonance Rayleigh scattering spectrum. At the same time, the reaction mechanism was discussed and the reaction model was proposed through comparing with the interaction of TGA-CdTe QDs (which was synthesized using TGA as stabilizer singly) with NR and combining with transmission electron microscope (TEM) technology. In pH 7.4 PBS buffer solution, the MB/MG binded to the surface of mono-6-thio-p-CD-CdTe QDs with monomolecular, and resuluted in the quchening of the fluorescence of mono-6-thio-β-CD-CdTe QDs through photoinduced electron (PET) transfer from the conduction band of QDs to the ground state of MB/MG; MB mainly combined withβ-CD on the surface of mono-6-thio-β-CD-CdTe QDs, and MG mainly combined with-SCH2COO-on the surface of mono-6-thio-β-CD-CdTe QDs. In the presence of hsDNA, the MB-quenched fluorescence of NCs could be reversibly restored by hsDNA as the PET pathway is blocked when MB is taken away from the mono-6-thio-β-CD-CdTe QDs surface. Based on it, the fluorescence of mono-6-thio-β-CD-CdTe QDs was reversiblely modulated. 3. The interaction of mono-6-thio-β-cyclodextrin capped CdTe QDs with malachite green and crystal violetCdTe quantum dots (QDs) capped withβ-cyclodextrin was synthetized using both TGA and mono-6-thio-β-CD) as stabilizer. The interaction of mono-6-thio-β-CD-CdTe QDs with malachite green and crystal violet was studied with fluorescence, UV-absorption and resonance Rayleigh scattering spectrum. At the same time, the reaction mechanism was discussed and the reaction model was proposed through comparing with the interaction of TGA-CdTe QDs (which was synthesized using TGA as stabilizer singly) with MG/CV and combining with transmission electron microscope (TEM) technology. In pH 7.4 PBS buffer solution, the CV/MG binded to the surface of mono-6-thio-β-CD-CdTe QDs with monomolecular, and resuluted in the quchening of the fluorescence of mono-6-thio-β-CD-CdTe QDs through photoinduced electron (PET) transfer from the conduction band of QDs to the ground state of CV/MG; the combination of MG with mono-6-thio-β-CD-CdTe QDs was different with CV, which rendered theΚSV of mono-6-thio-β-CD-CdTe-MG greater than mono-6-thio-β-CD-CdTe-CV, at the same time the RRS intensities of mono-6-thio-β-CD-CdTe-MG was markly enhanced, and the RRS intensities of mono-6-thio-β-CD-CdTe-MG had no significantly change. Based on it, RRS method selectively recognited MG using mono-6-thio-β-CD-CdTe QDS as a probe.
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