Studies On The Mechanism And The Interaction Between Water Soluble CdTe Quantum Dots And Biomolecule

Semiconductor quantum dots (QDs), because of their unique optical profiles,are considered to be an ideal fluorescence probe applied to super sensitive detect,multicolor and multicomponent analysis,tumor target cell medicine selection and developing in the field of molecule biology and bioengineering. In this dissertation, we focused on the mechanism of reaction between CdTe QDs and small biomolecules. The detailed contents and results are as follows:1. Interaction between CdTe QDs and adenine is investigated by using fluorescence spectra, absorption spectra, infrared spectrometry and transmission electron microscopy in order to find the mechanism of QDs reacting with some biomolecules such as DNA and enlarge the application of QDs in biomedicine field, especially inimmunity detectction.(1) CdTe can combine with adenine molecule, the reaction condition has great effect on the PL intensity of conjugates. In order to obtain higher PL intensity and more stable conjugates the condition should be controlled in a lower ionic strength solution, less than 1h reflux time, neutral pH and 0.2-5 as molar ratio of adenine to CdTe.(2) The PL intensity of CdTe-adenine conjugate is the higher than that of CdTe-guanine, both of them are more than that of CdTe itself. After several days under low temperature the PL intensity of CdTe-guanine conjugate attenuates sharply whereas the PL intensity of CdTe-adenine decreases slowly. One conclusion is that the coordination, hydrogen bonding and conjugated structure of adenine can make great influence on the PL intensity. It can affect the stability of the conjugates. And the PL peak positions of CdTe-adenine, CdTe-guanine conjugate, CdTe QDs under low temperature are constant.(3) The mechanism of the conjugation between CdTe and adenine has been investigated by TEM, fluorescence microscope and photoluminescence (PL), IR, UV-vis spectra analysis.2. We use doxorubicin hydrochloride (DH) as drug, tamoxifen (TF) as P-glycoprotein inhibitor to chemically modify the surface of orange and green CdTe QDs, respectively. Further the interaction mechanism between peptide of P-glycoprotein and two probes (red emitting-CdTe-DH, green emitting-CdTe-TF) was analyzed based on the results obtained from IR, PL, and UV–vis spectra.The interaction between peptide and CdTe-DH can enhance the PL intensity, and the peak position of CdTe-DH-peptide is stable, comparing to pure CdTe-DH. The same tendency can also be seen for PL intensity and peak position of CdTe-TF-peptide. It may be result of coordination and hydrogen bonding between peptide and CdTe-DH or CdTe-TF.