Study On Novel Biosensors Based On New Bionic Materials As Immobilization Interface

Bionic materials are a kind of materials based on the imitation of characteristics of natural creatures, which possess special morphologies or properties and many applications. Bionic materials can keep the bioactivity of biological molecules due to the good compatibility, and consequently be widely used in biochemistry.The third generation biosensor based on direct electron transfer is an advanced technology, it possesses many advantages, such as small size, high sensitivity, short response time, no need for pretreatment of samples, and low cost. Therefore, biosensor has wide application in many fields, such as medical science, military, environmental monitoring and food security. The key to the construction of biosensor is the preservation of the bioactivity of the biological molecules. Therefore, several kinds of biosensors were fabricated using novel bionic materials. Details are summarized as follows:Part 1 Amperometric hydrogen peroxide biosensor based on electro-codeposition of chiral zirconium phosphonate/Hemoglobin on gold electrodeA new kind of material-chiral zirconium phosphonate (Zr(P04)(H2PO4)0.50·(H03PCH2NCH2SC2H3COOH)o.5o-1.6H20) (abbreviated as ZrPMT), was employed for the construction of hydrogen peroxide biosensor. UV-Vis absorption spectra displayed that hemoglobin (Hb) retained its native structure after interaction with ZrPMT, showing that ZrPMT provided good compatibility. Cyclic voltammetry experiment showed that ZrPMT could greatly improve the electron transformation between the modified electrode and electrolyte. The biosensor was prepared by electro-codepositing of ZrPMT and Hb onto gold electrode (Au), this method was simple and easy, and the biosensor exhibited good response to the reduction of hydrogen peroxide with linear range from 5×10-7 mol L-1 to 1.2×10-4 mol L-1, and detection limit of 1.6×10-7 mol L-1, coefficient constant of 0.99 (S/N=3), the stability and selectivity were also good.Part 2 Enzyme biosensor based on Hemoglobin entrapped in intestine-like SnO2 nano-cluster A new morphology of SnO2, intestine-like nano-cluster was employed for the fabrication of hydrogen peroxide biosensor. The prepared SnO2 exhibited excellent biocompatibility and adsorption of hemoglobin, and the biosensor constructed by electro-codepositing of SnO2 and hemoglobin on gold electrode exhibited sensitive response to the reduction of hydrogen peroxide, and the linear range was from 1×10-5 mol L-1 to 1.6×10-2 mol L-1 with coefficient constant of 0.99 (n=23), and the detect limit was estimated to be 3.5×10-6 mol L-1 (S/N=3). The selectivity, reproducibility and stability were also good.Part 3 A novel label-free electrochemical immunosensor for the detection of a-fetoprotein based on graphene/chitosan compositeA novel label-free immunosensor was fabricated for the detection of a-fetoprotein. The construction process of the immunosensor was firstly cast chitosan/graphene composite on the electrode, and then adsorbed nanogold particles on the composite, and finally adsorbed a-fetoprotein antibody. This method is very simple and the proposed immunosensor possessed high sensitivity, good selectivity and reproducibility, the detect range was from 0.01 to 20 ng mL-1 with a detect limit of 3 pg mL-1 (3σ), and the regrssion equation was△I (μA)=0.569+0.984 CAFP (ng mL-1) with a coefficient of 0.998, showing potential application in clinical diagnosis.