Electrochemical Detection Of Tumor Markers Based On Polyaniline Derivatives

Polyaniline and its derivatives have attracted much attention to be used as electeochemical immunosensor and chemosensor due to its unique and controllable optical and electrical properties. In this thesis, a label-free electrochemical biosensor for CEA and a multiplexed immunoassay for simultaneous electrochemical determination of CEA and AFP were prepared based on PATP, PODP/Au nanocomposites and poly(VFc-ATP)/Au nanocomposites, respectively. Moreover, a novel sensing system for Co2+detection was fabricated based on the special interaction among MB, ATP, and Cu2+. The results are summarized as follows:1. A multiple thiols conjugated polymer, PATP, which contains25repeated units was synthesized by chemical polymerization process and combined with gold nanoparticles (AuNPs) by Au-S bonds to fabricate a novel, sensitive, and label-free amperometric immunosensor for detection of CEA. The PATP not only acted as an electron transfer media in the recognition process but also provided tenacious attachment to the electrode due to the multiple thiols group. The immunosensor exhibited wide linear range (1fg mL-1-10ng mL-1) and low detection limit (0.015fg mL-1). Meanwhile, the electrochemical immunosensor was applied for the determination of clinical serum specimens, and the results were in accordance with those of the micropartical enzyme immunoassay (MPEI).2. POPD/Au and poly(VFc-ATP)/Au) nanocomposites were synthesized by one-step method. They were novel nanocomposites with advantages of good biocompatibility, diacritical potential, facile synthesis and easy modification. Based on the above advantages and the excellent redox-activity of POPD and poly(VFc-ATP)/Au), the redox-active polymer/Au nanocomposites were successfully used to prepare the probes of tumor markers and fabricate a multiplexed electrochemical immunosensor for simultaneous detection of CEA and AFP. The performance of the immunosensor was studied by elelctrochemical method. The simultaneous monitoring of CEA and APF was in a wide range of0.01-100ng mL-1and the detection limits (LOD) was0.006ng mL-1and0.003ng mL-1(S/N=3), respectively. In particular, the assay results of serum samples with the proposed method were well consistent with the reference values from standard MPEI method.3. A novel colorimetric method was developed for the sensing of Co2+ions based on the interaction of MB, ATP and Cu2+which formed a special complex (MB-ATP-Cu2+). Based on controlling the oxidation level of MB by the concentration of Co2+, the color of the sensing system was varied. The Co2+ions can therefore be easily achieved by visual method. The linear range and detection limit of the sensor was0.1mM-1.1mM and0.04mM (S/N=3), respectively.