| Nitric oxide (NO), a radical diatomic molecule, exists widely in living organisms and has strong biological activity, NO is produced endogenously from L-arginine by a family of enzymes called nitric oxide synthases (NOSs). It is an important messenger molecule, which has been found to be active in the cardiovascular, nervous, and immune systems, and in the wound-healing process. Exogenously NO donors and NO synthase inhibitors play important roles in clinical application. However, the over concentration of NO is harmful to the living health. So it is very important to explore the sensitive and selective analytical techniques capable of its measurement and quantification. Of the known techniques, electrochemical sensors represent one of the most promising approaches. It has many advantages, such as high sensitivity, quick response, real-time measurements in vivo and single cell analysis. Electrochemical sensors depend on the distribution of the modified film to obtain sensitivity and selectivity response. So it is essential to design suitable sensing interface with molecular sensitive, energy transfer effective and high catalytic activity and investigate the sensing mechanism.Photoelectrochemical sensor has low background signal and high sensitivity for employing the optical excited source and electrochemical detector. With simple equipment and easy operation, photoelectrochemical sensor has extraordinary superiority on molecular recognition and analysis. Based on nanoparticles with high catalytic activity and some functional materials, we have designed some novel sensing interface with high sensitivity, selectivity and catalytic activity to develop new NO electrochemical and photoelectrochemical sersors. Moreover, we investigated the application value of the sensors in the biomedicine field. The main works are summarized as follows:(1) MWNT/WO3hybrid nanostructures were prepared by solvothermal synthesis. The results of TEM showed that WO3nanoparticles were adsorbed on the surface of MWNT homogeneously, forming a hybrid nanostructure. We designed a sensitve NO sensing interface and prepared a NO electrochemical sensor based on MWNT/WO3/Nafion/GCE. Electrocatalytic oxidation of NO was realized sensitively on the sensing interface. A good linear relationship between the amperometric response of the sensor and the concentration of NO in the range of36nmol/L～1.0μmol/L was achieved, along with a low detection limit of18nmol/L (S/N=3). The selectivity was improved by applying the permselective Nafion film. The NO sensor was used to detect the NO released from different donors, such as sodium nitroprussiate and sodium nitroprusside with the white light irradiation, and the results were satisfied.(2) A simple electroless plating method for growing a gold nanoparticles (GNPs) film on a quartz fiber by chemical liquid deposition was reported. The gold film coated quartz fiber possessed good conductivity and mechanical property, and can be used as a novel gold fiber microelectrode (GFME). Being electropolymerized with niacinamide (NA) and further coated by Nafion for GFME, a disposable nitric oxide (NO) electrochemical microsensor was fabricated. The microsensor exhibits a wide linear range (7.2nmol/L～18μmol/L) and a low detection limit of2nmol/L (S/N=3). Additionally, it can efficiently resist the interference of many coexistent substance (such as ascorbic acid and uric acid). The present work demonstrated that GFME, with the merits of easy fabrication, low cost, good mechanical property, excellent conductivity and high homogeneity, was a promising disposable microelectrode platform for biomedical analysis.(3) Based on acetylene black nanoparticles, we prepared a low cost carbon paste microelectrode by simple filling method. The organic dye molecular methylene blue was electrodeposited on the surface of the carbon paste electrode and a layer of Nafion film was casted to obtain a new NO microsensor. Electrocatalytic oxidation of NO was realized sensitively on the sensing interface.The NO microsensor possessed a wide calibration range from18nmol/L to76μmol/L, a response sensitvity of0.12μA/μmol/L, a low detection limit of9nmol/L and good anti-interference ability. It was successfully applied in the detection of NO released from rat liver homogenate.(4) Gold nanoparticles (GNPs) electrode-on-paper array was prepared by inkjet printing, on which hemoglobin (Hb) was incorporated in reduced graphene oxide (rGO) modified film. Hb/rGO/GNPs biosensor array combined the excellent properties of GNPs and rGO. A pair of well-defined and quasi-reversible cyclic voltammetric peaks was obtained, which reflected the direct electron transfer of heme protein. The immobilized proteins retained their biocatalytic activity to the reduction of NO and hydrogen peroxide, which provide the perspective to be the disposable and environment-friendly biosensor array.(5) The polyhydroquinone (PH2Q) was prepared by the oxidation-based self-polymerization of hydroquinone. Fullerenes (C60) was functionalized by PH2Q through noncovalent π-π interactions, providing a simple but effective approach to prepare the water-soluble C60/PH2Q suspension with high stability and solubility. A cathodic photocurrent response of NO was observed on C60/PH2Q modified ITO electrode under visible light radiation, indicating the reduction of NO was catalyzed by C60with optical radiation. There was good linear relationship between the cathodic photocurrent and NO concentration in the range of0.2μmol/L～100μmol/L, along with a low detection limit of40nmol/L. So a NO photoelectrochemical sensor based on C60/PH2Q/ITO was developed. The main interferent NO2-has no apparent photoelectrochemical response on the sensor, revealing the high selectivity of NO photoelectrochemical sensor. Addionally, it was demonstrated that C60can eliminate NO radicals effectively, implying the application value of C60in the biomedicine and clinical field. |
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