Synthesis Of Precious Metals Nanomaterials And Their Applications In Photometric Analysis And Electrochemical Biosensors

The precious metal nano-materials were applied to the analysis of heavy metalions and biological molecules detection. The advantages, such as sensitivity fast andconvenient detection, maniputatity and selectivity, have attracted more and morescientific researchers. The research have developed electrochemical aptamer sensorbased on the special optical properties of gold nanorods and good biologicalcompatibility and Pt@Ir binary alloy nano-materials of good catalytic performancehave been applied in detecting Cu2+, optical sensors and carcinoembryonic antigencodeine, microcystins-LR (MC-LR) of electrochemical sensors have been prepared,those have achieved satisfactory results. The details are summarized as follows:(1) Based on the literature reported that the preparation of gold nanorods (GNR),we have adopted the method of the growth of the seeds mediated and synthesisedGNR that length to diameter ratio of about3. When there are Cu2+in solution, thegold atoms will cause a complexation reaction with sodium thiosulfate (Na2SO3)andammonia (NH3·H2O), and gold atoms can be oxidized, which leaded to GNR’sstructure change,we can use UV-visible spectrophotometry to detect the change ofabsorbance,which can reflect the solution of the initial amount of Cu2+indirectly. Theoptical sensor detection range from5nM to500mM with a detection limit of1.6nM.(2) GNR was coated with poyl(styrene sulfonate)(PSS) and poyl(allylamine)hydrochloride (PAH) by layer-by-layer (L-B-L) deposition. Hexadecyl trimethylammonium bromide (CTAB) was on the surface of GNRs, which we can develop anovel method for detection of carcinoembryonic antigen (CEA). When the CEA andanti-CEA react selective specifically. Consequedtly GNRs self-assembly will be made,which can make UV-visible absorption spectrum change, so we can realize the CEAquantitative detection. Using electrochemical impedance spectroscopy and cyclicvoltammetry were investigated of different combination to GNR surface modificationlayer changes; Besides, the research also investigated the solution’s pH, thecombination time of anti-CEA with CEA, the impact of the correspondingsignal.Results show that the method has a liner relationship with the concentration ofCEA ranging from10ng/mL to100ng/mL, with a detection limit of3.3ng/mL.(3) A novel aptamer sensor for rapid determination of codeine, goldnano-particles (GNP) was synthesized by solvothermal method, and the adsorption ofGNP polyamide-amine resin polymer (PAMAM) fixed on the screen printing electrode by chitosan (CHIT), by using of the strong bond between goldnano-particles (GNP) and hydrosulphonyl, so we can take advantage of these strongbound to immobize wite sulfychyl codeine aptamer on the screen electrode surfaceindirectly. When aptamer was incubated with different concentrations of codeine,codeine aptamer will combine with codeine specificityly, which hampering theelectron’s transfer and reducing the response of current. As the increase ofconcentration of codeine, the more combination between codeine and codeine’saptamer, the less current respond. According to the current decreases, the quantitativedetection of codeine can be finished. The research investigate liquid conditions suchas pH and cultivating time affect the performance of the sensor. The Results showedthat the pH of7.2and the range of the sensor detection1pM~1M, with detectionlimit of0.33pM. The sensor preparation is simplicity, sensitivity and stability.(4) Pt@Ir binary alloy nano-particles were synthesized by solvothermal methodand were labled on micro capsule algal toxins coupling antigen (MC-LR-BSA).Thescreen printed electrode were modified chitosan,by using glutaraldehyde crosslinkingeffect of microcystin algae toxin antibody (Anti-MC-LR) fixed to the electrodesurface to develop competitive microcystin algae toxin immune sensor.Through theMC-LR and Pt@Ir-MC-LR-BSA and Anti-MC-LR specificity competitioncombination, catalyzed by chronoamperometry test Pt@Ir H2O2produced by thereduction in current value to detect of MC-LR in the solution. The current value of thereduction of H2O2catalysed by Pt@Ir was inversely proportional to the consentritionof MC-LR. The experimental conditions, such as incubation time, antibodyconcentration and the volum ratio of antigen with labeled antigen were studied. Theresult showed that the biosensor has a detectation ranging from0.1ng/mL to50g/mL, with a detection limit of0.033ng/mL, and the sensor has a good selectivity.