| Electrochemical biosensor is a novel interdisciplinary frontier which includes thespecialty of chemistry, biology, physics and ebctronics. Because of the high sensitivity, fastresponses and advantages in miniaturization and online detection potentials, electrochemicalbiosensors have been extensively applied in clinical medicine, food inspection andenvironment protection, mnomaterials, have been widely used for the constructing ofelectrochemical biosensors which relate to their uniqueproperties of size effect, surface effect,macro quantum effect and dielectric confinement effect. The application of nanomaterials hasbrought a great of momemumto electrochemical biosensors and opens mwhorizonsfor hightysemitive detection. In this paper, we studied on the the novelelectrochemical biosensors basedon nanomterials, the detail list as below:The fist: A homogeneous CdS-PVA nanocomposite dispersion was obtained by mixinghollow CdS nanospheres in polyvinyl alcohol （PVA） solution under ultrasonic condition.Then the dispersion was dropped on a glassy carbon electrode for dryness to obtain theCdS-PVA modified electrode. Further, a novel DNA biosensor for Escherichia Coli wasfabricated by covalent immobilization of Escherichia Coli gene related oligonucleotides onthe modified electrode using terephthalic acid as the arm linker. The analytical performance ofthe biosensor was investigated by electrochemical impedance method, and the results revealedthat the constructed biosensor had a wide dynamic range from1.0×10-12mol/L to1.0×10-7mol/L and a low detection limit of1.3×10-13mol/L. The selectivity experiments showed thatthe DNA biosensor could accurately discriminate the complementary sequence from thesingle-base mismatched, three-base mismatched and noncomplementay sequences. When thebiosensor was applied for the detection of the real sample of Escherichia Coli, a satisfyingresult was obtained.The second: In this work, a novel rugby-ball shaped CoS nanoparticles （rCoS） wereprepared via hydrothermal method and their components and morphologies werecharacterized by scanning electron microscope and transmission electron microscope. AnovelpTSC/rCoS modified electrode was obtained by electro-polymerizedthiophene-2-sulfo-chloride on glassy carbon electrode with rCoS nanoparticles. Electrochemical impedance spectroscopy showed that the modified electrode possess goodperformance due to the good conductivity and the nanometer size effect of rCoS nanoparticles.Then a new style electrochemical DNA biosensor was fabricated by covalent immobolizatonof the ammonia modified Escherichia Coli gene segments with functional groups ofelectroplymerized2-thiophene sulfo-chloride polymers （TSC） on the modified electrode（S1/pTSC/rCoS/GCE）. DNA hybridization assays suggested that the target DNA could bequantified over a wide dynamic range of1.0×10-13mol/L to1.0×10-7mol/L with a lowdetection limit of1.14×10-14mol/L using methylene blue （MB） as an electro-chemicalindicator. In addition, the hybridization specificity experiments showed that the DNAbiosensor could accurately discriminate the complementary sequences from the single basemismatched, three base mismatched and noncomplementay sequences. This work describes asimple strategy for the preparation of a stable and conductive interface for electrochemicaldetection of DNA hybridization and opens a path for the application of rCoS nanoparticlesand2-thiophene sulfo-chloride polymers in DNAelectrochemical biosensing analysis.The third: The direct electrochemistry of hemoglobin （Hb） embedded in a novel supportmatrix of broccoli-like Bi2S3and Chitosan （bBi2S3-CS） nanocomposite on a glassy carbonelectrode was studied. The prepared bBi2S3-CS is of good biocompatibility, enhanced electricconductivity and large specific surface area. The immobilized Hb in bBi2S3-CS displaysexcellent direct electrochemistry and retains its biocatalytic activity toward the reduction ofhydrogen peroxide. The electrochemical signal shows a linear response to H2O2in theconcentration range from4.0×10-6to7.6×10-5mol/L with a detection limit of6.7×10-7mol/L.The results demonstrate that the bBi2S3-CS nanocomposite offers a biocompatible material forthe construction of biosensors.The forth: The direct electrochemistry of hemoglobin （Hb） embedded in a novel supportmatrix of MnS nanocomposite on a glassy carbon electrode was studied. The prepared MnS isof good biocompatibility, enhanced electric conductivity and large specific surface area. Theelectrochemical signal shows a linear response to H2O2and TCA. |
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