Fabrication Of Various Molecular Recognition Biosensing Active Interfaces And Their Application Research

As an advanced monitoring method to develop biotechnology, biosensor is a multidisciplinary approach which is composed of molecular recognition component and transduction element. It has wide application prospects in pharmaceutical analysis, foodsafety, industry control, clinical diagnosis,biochip technology and environmental protection. The biosensor interface fabrication is a crucial step in biosensor design, which directly influences the electrochemical performance of biosensor, such as sensitivity, limit of detection, linearly range and stability etc. This thesis focus on developing new functional materials and immobilization technology for constructing quartz crystal microbalance (QCM) affinity biosensor and hydrogen peroxide, glucose biosensor, and investigate their applications in bioanalysis field. The main Research contents and results are as follows:(a)A novel QCM affinity biosensor based carboxylated multi-walledcarbon nanotubes(MWCNTs) immobilized onto the platinum electrode for real time monitoring the interaction between interleukin-6(IL-6) and solubleinterleukin-6receptor (sIL-6R). The results showed that the apparent equilibrium association constant (Ka) and Dissociation Constant (KD) are respectively. This results are consist with traditional way’s, revealing the reliability and scientificity of this method. Moreover, as a simple technology, this method not only provides a possibility for monitoring the interaction of biomacromolecules more efficiently, but also has broad application prospects in studies on the action mechanism of traditional Chinese medicine, which will greatly extend the biosensor’s application range.(b) The amperometric non-enzymatic hydrogen peroxide biosensor based on poly(vinylalcohol)(PVA)/MWCNTs/Platinum nanoparticles (PtNPs) nano-composite film was constructed. In this hybrid film, the PtNPs were electrochemical deposited onto the surface of MWCNTs which were non-covalentlyfunctionalizedby freezing-thawingPVA. Since the synergic effect of MWCNTs and PtNPs, the PVA-MWCNTs-PtNPs film modified electrode exhibited excellent electrocatalytic performance for H2O2, such as awide linear range(0.002-3.8mM), a remarkable sensitivity(122.63μA mM-1cm-2), a low detection limit (0.7μM) at the signal-to-noiseratio of3and a fast response time (within5s). In addition, the as-prepared sensor also showed long-termstability, excellentreproducibility and anti-interference performance. The current construction method canprovidea feasiblemeanand development platform to fabricate other non-enzymatic sensors.(c) Aseriesof different morphology of copper nanomaterials, such as copper nano-particles, bulks, dendrites and flowers were prepared by direct electrochemical position process from coppersulfate (CuSO4)precursor through the change of reaction conditions. The morphology was characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), and X ray diffracmeter (XRD). The growth mechanism of copper structures was also illustrated in detail. The electrochemical performance of the copper nanodendrites and its oxidation catalytic activity towards glucose in NaOH solution were detected by electrochemical workstation. The results showed that the copper nanodendrites modified electrode exhibited good catalytic activity towards glucose in the absence of enzyme. At the work potential of0.55Vvs. Ag/AgCl, it displayed fast current response, low detection limit and wide detection range. Meanwhile, it possessed good stability, anti-interference, and repeatability.(d) A novel enzyme-free biosensor based on copper oxide nanoleaves which were prepared through a film plating/potential cycling method (consecutive two-step electrodeposition). The resulting sensor showed excellent electrocatalytic activity to glucose and H2O2in0.1M NaOH solution. For the glucose detection, the sensor showed a high sensitivity of53.19μA mM-1, a wide linear range of12.5μM-4.29mM, and a low detection limit of4.17μM. Furthermore, the as-prepared sensor exhibited long-time stability, good anti-interference, and reproducibility.(e) The reduction graphene oxide (RGO) was obtained through the reaction of chitosan (CS) and graphene oxide (GO) in the high temperature of90℃for10hours. Then the gold nanoparticles (AuNPs) were modified onto the surface of RGO through high temperature reduction. The resulted CS-RGO-AuNPs hybrids were employed to immobilize glucose oxidase (GOD). The glucose biosensor based on GOD/CS-RGO-AuNPs modified Pt electrode was developed and its electrochemical properties were detected by cyclicvoltammetry and chronoamperometry methods. At the work potential of0.5V vs. Ag/AgCl, it showed a high sensitivity of102.4μA mM"1cm-2, a low detection limit of1.7μM (S/N=3), and a wide linear range of0.015-2.13mM. This good performance is attributed to synergic effect of RGO and AuNPs, such as large specific surface area, rapid electron transferring etc. Moreover, the CS provided a suitable microenvironment to keep GOD bioactivity.