Spectroscopic Studies Of Interaction Among Cdte Quantum Dots, Antioxidant Drugs And Protein, Polypeptide

In this paper, we synthesized3-mercaptopropionic acid (MPA) capped CdTe quantum dots (CdTe QDs) in aqueous solution.The prepared QDs were characterized by using atomic force microscope (AFM), transmission electron microscope (TEM), fluorescence microscope (FM) and X-ray powder diffraction (XRD). The mechanisms of the interactions among QDs, a series of antioxidant drug molecules and proteins, peptides were explored by fluorescence spectroscopy (FL), ultraviolet-visible (UV-vis) absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR) and electrochemical measurement. Additionally, simple and sensitive spectroscopy assays for determining antioxidant drug molecules and proteins were proposed. The work also has some significance for metabolism and antioxidant activity of drug molecules.The main contents are as follows:1. Interaction of flavonoids (baicalein and hesperetin) with CdTe QDs by optical and electrochemical methods and their analytical applicationsInteractions between CdTe QDs and two flavonoids (baicalein and hesperetin) were investigated by fluorescence spectroscopy, UV-vis absorption spectroscopy, and electrochemical measurement. The results showed that, baicalein and hesperetin could linear quench the fluorescence of the QDs significantly via electron transfer progress within a certain range of concentrations. Based on this, a sensitive and simple assay for detecting baicalein and hesperetin was proposed which using QDs as fluorescent probe. Under the best experimental conditions, the linear range for baicalein and hesperetin were32.0-5.0×104ng·mL-1and82.0-1.2×105ng·mL-1, respectively, and the limit of detections (3δ) for baicalein and hesperetin were9.7ng·mL-1and24.5ng·mL-1, respectively. The recovery of spiked baicalein and hesperetin in human urine ranged from98.5%to99.4%and100.2%to104.7%respectively. We also studied that different fluorescence quenching efficiency of QDs by baicalein and hesperetin is partly related to the antioxidant activity of flavonoids.2. Study of interaction between resveratrol and human serum albumin via QDs photoluminescence turn-on mode and highly sensitive strategy for protein determinationHerein, we described a new highly sensitive strategy for fluorescent detection of human serum albumin (HSA) via a photoluminescence turn-on mode. The strong fluorescence of CdTe QDs can be quenched significantly by resveratrol (RES) and restored gradually by adding HSA based on the fluorescence resonance energy transfer (FRET) from HSA to RES, which has the potential for HSA quantification. As expected, the developed method for detecting HSA showed a good linearity for the calibration plot with a detection limit (3δ) of8.0ng·mL-1and a linear range of26.6-1×105ng·mL-1. This strategy was successfully applied to synthetic samples, whose recovery range is from99.7%to100.3%, and demonstrated ideal selectivity.3. Reversible control of fluorescence based on the interaction among CdTe QDs, CHA and Ang ⅠElectron-hole recombination of CdTe QDs was blocked by Chlorogenic acid (CHA), which leads to the fluorescence quenching of QDs. The fluorescence intensity of QDs against the concentration of CHA showed a good linearity in a certain range of concentrations (correlation coefficient R=0.9985). Determination of CHA by fluorescent spectrometry was provided on this account. Angiotensin Ⅰ human acetate salt hydrate (Ang Ⅰ) could restore the fluorescence of QDs which was quenched by CHA, Ang Ⅰ interacted with CHA, which result in CHA far away from the surface of QDs, and served as the main reason for fluorescence restoration of QDs. Thus reversible control of fluorescence of the QDs was realized.