| The problem of environmental pollution, food safety and disease has threated the humanlife and health, it is urgent to be solved. Based on the electrochemical and optical detectiontechniques, such as electrochemical biosensors and surface enhanced Raman, provideefficient ways for low concentration toxic substances and biological molecules. Nanoporousgold (NPG) film is a kind of functional macromaterial. Specific surface area of thenanoporous gold has attracted considerable attention in trace-level molecular detection andanalysis in catalytic and surface plasmons systems. The assemble methods of nanostructureelectrodes are usually using adhesive or direct physical contacting, in which there are greatresistances. The low moleculer detection sensitivity, corresponding delay, poorreproducibility and stability influence catalysis and sensing. The extraordinary opticalproperties of nanostructured noble metals arising from surface plasmon resonance (SPR)have received increasing interests in fundamental research and technological applications inphotonic devices and biosensors. One of the most important applications ofsurface-plasmon-based techniques is surface enhanced Raman scattering (SERS) for probingand identifying tracelevel molecules in chemical and biological systems. Traditionalmaterials usually use metal sol, metal solid phase interface and metal ionl films, who havethe poor uniformity and stability, nanoporous gold (NPG) films have been demonstrated tobe promising SERS substrates and the unique bicontinuous nanostructure with nanosizedgold ligaments and pores enables NPG to provide reliable and excellent SERS signals. Themain contents are as follows:1. Diabetes has become one of the eight major threatening health diseases, its mortalityrate is as high as2.6%. Diabete patients need to monitor the glucose concentration daily, sothe development of high sensitivity, high selectivity, short response time and high stability ofthe glucose sensor becomes one of the focuses research. People usually use enzyme modifiedmaterials such as precious metals as the working electrode for glucose detection, butprecious metals such as platinum or gold electrode in the process of electric catalytic glucoseeasily adsorbed intermediate make the electrode passivated. And the enzyme activity issusceptible to temperature, the pH of the solution and the influence of poison material.Recently, people began to turn your attention to metal or metal oxide materials and the oxide compound electrode.(1).We synthesized solid/nanoporous Au by the method of multicyclic electrochemicalalloying/dealloying method based on a three electrode electrochemical cell.,Solid/nanoporous Au belongs to seamless integration metal material do not rely on usingadhesive or direct physical contacting. Thre is no resistance between them. In the preparationprocess, adusting the characteristics scale by changing the experiment conditions. Theseamless S/NPG wires were prepared by a multicyclic electrochemical alloying/dealloyingmethod based on a three electrode electrochemical cell, in which Zn plate and wire wereused as the auxiliary electrode and the reference electrode in a BA electrolyte containing1.5M ZnCl2, respectively.3D bicontinuous nanoporous layer with tunable microstructuralfeatures was decorated on polished Au wires，The seamless solid/nanoporous structurepossesses~1mm thick nanoporous layer, where a uniform and3D bicontinuous nanoporousstructure consists of quasi-periodic nanopore channels and Au ligaments with characteristiclength of~300nm，and the toughness is perfect.(2).We synthesized solid/nanoporous metal/oxide hybrid electrode by using thesolid/nanoporous Au as the basical metal, the multifunctional seamless solid/nanoporousAu/Co3O4hybrid microelectrodes are fabricated for nonenzymatic electrochemical glucosebiosensors by growing the Co3O4nanoparticles in the nanoporous gold ligament. Theelectrodes have broad contact area helful for transmission of ions and mass. on theelectrochemical detection of glucose concentration, the research results show that thecomposite electrode in glucose sensor detection showed a very superior performance, at thelow potential, the free enzyme glucose electrochemical biosensor micro electrode in the testshow the high sensitivity, good reliability and rapid response (<1s), the highest sensitivitycan reach to12.5mA mM-1cm-2. The hybrid microelectrode provides superb selectivity forglucose detection at the low applied potential of0.26V, which minimizes the responses ofcommon interference species such as uric acid, acetamidophenol and ascorbic acid, inphysiological levels, as well as other sugars. The predominant properties enlist this hybridmicroelectrode to exhibit high reliability for analyzing blood serums. The electrochemicalstability of the S/NPG/Co3O4hybrid microelectrode is investigated by thechronoamperometric method in four fresh solutions containing0.5M KOH and10mMglucose. In spite of the slow decrease of the current with time, the starting current responsemaintains stable in each fresh electrolyte, revealing the good stability of the hybridmicroelectrodes during the electrochemical measurements. This is also confirmed by UV–visible spectrum of the measurement solution, where no Co or Au ion is detected. Eventhe S/NPG/Co3O4hybrid microelectrode stored at room temperature for4months stillmaintains the high capability to analyse serum sample at ultralow concentrations. It shouldbe noted that a response time no more than1s to research95%of steady-state current.2. The Raman spectroscopy can provide rich information of the molecular structure, theadvantages make the SERS technology become an important tool in the field of biochemicalanalysis, the high-speed development of SERS technology greatly improves the detectionsensitivity of Raman spectrum, which overcome the shortfalls of Raman spectroscopy,surface plasmon resonance (SPR)have received increasing interests in fundamental researchand technological applications in photonic devices and biosensors. One of the mostimportant applications of surface-plasmon-based techniques is surface enhanced Ramanscattering (SERS) for probing and identifying tracelevel molecules in chemical andbiological systems. SERS active substrates usually use different shapes of colloid Au and Agnanoparticles, and when these particles come in pairs or a polymerization can generateelectromagnetic fields "hot spots", which can detect single molecule, on the downside,random combination of colloidal nanoparticles structure have poor reproducibility, stability,lead to the SERS effect of reliability, Hinder the performance of SERS sensor for widelyused. The structure which was constructed by embedding oxide nanoparticles into bimetallicnanoporous AuAg membrane, could control the pore size of porous gold substrates and thesize of oxide particles. At the same time, oxide has good stability and the nano-silver shellhas high SERS enhancement factor, typically102-103times compared with gold. We realizea facile and effective strategy for preparing the structure of largely embedding SnOnanoparticles into bimetallic nanoporous AuAg membrane (NP Au/SnO/Ag), only growing alayer of SnO nanoparticles on nanoporous gold film and covering Ag film on thatsubsequently to form a sandwich-like structure embedded oxides into bimetallic membrane.The sandwich-like structure as SERS active substrate has a high density and uniform “hotspots”, being very useful for vibrating or non-vibrating molecular. Embedding high-densitySnO nanoparticles into bimetallic nanoporous AuAg membrane is to produce a lot of “hotspots” in Au/SnO/Ag sandwich-like structure; this enhances the SERS effect of the wholeNP Au/SnO/Ag film immensely and the uniformity is very good. The enhancement factor(EF) is~1010, four orders of magnitude higher than that of NP AuAg and NP Au membranestructure. The high sensitivity even make the detecting concentration of folded NPAu/SnO/Ag film low as vibrating molecular R6G (10-15M) and that of cysteine with a small scattering cross section low as non-vibrating molecules (10-10M). |
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