The Preparation Of Polyamidoamine Dendrimers And Their Application On Sensors

Dendrimer is a new type of functional macromolecule compound that have special characters of designing the molecular size, shape and functional group at the molecular level. Synthesis and properties of Dendrimer is becoming the focus gradually in the macromolecule field, recently. It also acquires a breakthrough in some application field, such as drug deliver, catalyst carrier, gene therapy, sensor etc. According to the characters of dendrimer structure, it is a very prospect research to study on the functionalization and application of molecular systematically and devoting to solving the practical problem in the traditional fields.This thesis is composed of four parts, which are as follows:1. A series of PAMAM dendrimers of 0.5~4.0 generation were synthesized by divergent method using ethylenediamine as a rawmaterial by means of Mickeal addition reaction and amidation reaction. Their structures were characterized by IR, NMR. Meanwhile their fluorescence and UV-Vis properties were studied. The results showed that PAMAM dendrimers have good optical property and wide prospect in the field of optical matericals. Also, the coordinations between Sm3+,Dy3+,Ce3+ and polyamidomine dendrimer were studied by the fluorescence spectrophotometric method. By experiments of reaction time, molar ratio of RE3+/PAMAM and pH value of solution, the best coordination conditions of rare earth ions (RE3+) and PAMAM were determined. These offer the theoretical foundation for the preparation of rare earth atom clusters, which were in the polyamidomine dendrimer and size controlled.2. Cobalt (II) polyamidomine dendrimer was prepared by cobalt chloride, glyoxal and polyamidomine dendrimer 5.0 generation reacting. The interaction of cobalt(II) polyamidomine dendrimer complex with herring sperm (hsDNA) have been carried out using methylene blue (MB) as the probe molecule by absorption and fluorescence spectroscopy and synchronous fluorescence spectroscopy. And salt effect on their interaction was discussed. The results showed that the interaction of complex with hsDNA was electrostatic. The effect of sodium chloride showed that sodium ion can significantly constrain the interaction of complex with hsDNA. 3. A new chemically modified gold electrode was prepared by covalent self-assembled using 3-mercaptopropionic acid as a modifier, then 3-mercaptopropionic acid and cobalt (II) polyamidomine dendrimer modified electrode was prepared by the covalent interaction. The sensor can be used to study the electrocatalytic oxidation of guanine. The effects of pH value, scanning rate and guanine concentration were discussed. It showed that the assembled electrode has obvious electrocatalytic activity on guanine and decreased the oxidation potential of the guanine. The guanine was measured in acetate buffer solution (pH=5.8), the detection limit is 6.6×10-7mol/L.4. Dendrimer encapsulated Au/Pd nanoparticles were prepared. The nanoparticles doping chitosan was modified on glass carbon electrode (GCE), and then a novel DNA sensor was prepared by a covalently action between amino group of electrode surface and phosphate group of DNA. The immobilization dsDNA was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Experiment results showed that the immobilized amount of DNA probe on modified layer increased. The DNA biosensor was adopted to study the antioxidant property of silk sericin. The results showed that sericin had very good antioxidant properties, scavenging·OH effect was the best when concentration of sericin was 0.90 mg/mL.