Electrochemical Biosensors Based On Novel Nanomaterials

Biosensor is a multidisciplinary research filed involved biology, chemistry, materials, electronics and physics. Electrochemical biosensor based on functional nanomaterials has many advantages, such as simple fabrication, high sensitivity, fast response and low cost, which has broad application in many fields including food, pharmaceutical, environmental monitoring and biomedicine. The main contents of this paper focus on the preparation of novel functional nanomaterials, and its application in electrochemical biosensor. The specific works are included as follows:(1) An electrochemical sensor of Cd2+ was constructed by electrochemical reduction of graphene oxide on the glassy carbon electrode(GCE). The determination of Cd2+ was proceeded by square wave voltammetry. The Stripping voltammetric behavior of Cd at the graphene modified electrode was studied. The amount of graphene, deposition potential, deposition time, pH and the supporting electrolyte were optimized. In comparison with the bare glassy carbon electrode, the response signal of the graphene modif ied GCE was obviously increased. Under the optimal conditions, the linear calibration curve ranges from 0.001 to 1 μg/mL. The linear equation was y= 27.8592x+0.3445(R=0.998). The detection limit was 0.001 μg/mL. The reproducibility and repeatability were also investigated with RSD of 2.56%(n=6) and 2.51%(n=6), respectively. Owing to its simple fabrication, high sensitivity, fast response, good stability and repeatability, the developed sensor can serve as promising electrochemical platform for the detection of Cd2+ in real samples.(2) We developed a novel strategy to synthesize gold nanoparticles(AuNP) by a green synthetic method. The AuNP were synthesized by using glucose as the reducing agent and polyvinylpyrrolidone as the stabilizing agent. AuNP is modified on the surface of glassy carbon electrode, and the modified electrode was applied to hydrogen peroxide(H2O2) detection by chronoamperometry. We optimized the amount of AuNP, the applied potential and the pH of phosphate buffer solution for H2O2 detection. AuNP exhibits excellent electrocatalytic activity for H2O2 reduction, such as an excellent sensing performance with a wide linear range from 0.005 to 3.5 mM H2O2, and a low detection limit to 2.0 μM. The developed electrochemical biosensor based on AuNP possesses advantages such as simple fabrication, fast response, exellent selectivity and relatively low detection limit.(3) Electrochemical reduction of graphene oxide was applied to prepare graphene. Copper sulfide hollow spheres were obtained using Cu2 O nanoparticles as sacrificial templates. We fabricated an electrochemical biosensor for hydrogen peroxide(H2O2) detection with nanocomposites of the reduced graphene oxide and CuS hollow spheres by chronoamperometry. The amount of graphene, the reduction time of graphene oxide, the amount of CuS hollow spheres, the pH of phosphate buffer solution and the applied potential were optimized. Under the optimized experimental conditions, the response current versus the concentration of H2O2 is in a linear range of 0.005 to 4.0 mM and the detection limit is 3.0 μM(S/N=3). The linear equation is y=7.1245x+0.3659(R=0.9989). The reproducibility was investigated with a RSD of 2.46%(n=3). The reduced graphene oxide and CuS hollow spheres have good synergistic effects, which can significantly enhance the amperometric response of the sensor toward H2O2. The de veloped H2O2 sensor based on reduced graphene oxide and CuS hollow spheres possesses advantages such as simple fabrication, fast response, good selectivity, wide linear range and low detection limit.