| There are many different categories of biomarkers, such as proteins, nucleic acids, polysaccharides, biological metabolites et al. in serum. The key to achieving an electrochemical biosensor for the specific quantitative detection is to prepare or synthesize materials. Electrochemical sensors are valuable analytical tools for detecting target analytes through the changes of electrochemical signals before and after the recognition between antibodies and antigens, lectin and glycans, aptamers and ligands et al., which own the advantages of good selectivity, high sensitivity and low cost. Therefore, this research mainly focuses on the preparation of nanocomposite and the selection of sensitive interface to construct the electrochemical sensors. The research contents are mainly as follows:1. Ultrasensitive electrochemical immunosensor based on orderly oriented conductive wires for the detection of human monocyte chemotactic protein-I in serumFor the first time, a simple, ultrasensitive and label-free electrochemical monocyte chemotactic protein-I(MCP-I) immunosensor based on orderly oriented conductive wires has been developed. A conductive wire, which is similar to an electron-conducting tunnel, was designed with Au nanoparticles(Au NPs) joined to Au@Pt core-shell microspheres via a cysteamine(CA) crosslinker. To enhance the sensitivity of the immunosensor, Au NPs were electrodeposited onto the gold electrode, and CA was self-assembled via strong Au-S covalent bonds, providing an appropriate surface and promoting electron transfer. Next, Au@Pt core-shell microspheres with large surface area were grafted onto the modified electrode to immobilize more MCP-I antibodies. MCP-I is an initiating factor and biomarker of atherosclerotic diseases. Under optimal experimental conditions, differential pulse voltammetry(DPV) current changes were used to detect MCP-I with a broad linear range of 0.09- 360 pg mL-1 and a low detection limit of 0.03 pg mL-1(S/N=3). The proposed immunosensor exhibited good selectivity, reproducibility and reusability. When applied to spiked serum samples, the data for the developed immunosensor were in agreement with an enzyme linked immunosorbent assay, suggesting that the electrochemical immunosensor would be suitable for practical detection.2. Ultrasensitive electrochemical biosensor based on reduced graphene oxide-tetraethylene pentamine-BMIMPF6 hybrids for the detection of ?2,6-sialylated glycans in human serumIn this paper, a simple, ultrasensitive and label-free electrochemical ?2,6-sialylated glycans biosensor based on reduced graphene oxide-tetra-ethylene pentamine-1-butyl-3-methylimidazolium hexafluorophosphate(BMIMPF6) hybrids was developed. Due to the abundance of amino groups from reduced graphene oxide-tetraethylene pentamine(rGO-TEPA) and the electrostatic interaction of BMIMPF6, bimetallic gold platinum alloy nanoparticles(Au Pt NPs) were densely adsorbed onto the surface of the nanocomposite, providing a large surface area available for the immobilization of Sambucus nigra agglutinin(SNA). AuPt NPs have excellent conductivity and catalytic activity, which can promote electron transfer between the electrolyte solution and the surface of electrode and can enhance the sensitivity of biosensor. SNA, which specifically binds ?2,6-sialylated glycans, was covalently immobilized on Au Pt NPs for specific detection of ?2,6-sialylated glycans in human serum. Under optimal experimental conditions, amperometric response changes were used to detect ?2,6-sialylated glycans with a broad linear range of 10 fg mL-1- 1 ?g mL-1 and a low detection limit of 3 fg mL-1(S/N=3). When applied to spiked serum samples, the recovery of the developed biosensor ranged from 100.8% to 101.4%, suggesting that the electrochemical biosensor would be suitable for the practical detection of ?2,6-sialylated glycans. |
PDF Full Text Request