ABSTRACT
A dual-photoelectrode molecular imprinted photoelectrochemical (PEC) sensor is first built for the determination of sialic acid (SA) without additional energy supply. Specifically, WO3/Bi2S3 heterojunction behaves as a photoanode to provide amplified and stable photocurrent for the PEC sensing platform, which is attributed to the matched energy levels of WO3 and Bi2S3 promoting the electron transfer and improving photoelectric conversion properties. CuInS2 micro-flowers functionalized by molecularly imprinted polymers (MIPs) are served as photocathode to recognize SA, avoiding the deficiency of high production cost and poor stability from biological enzymes, aptamers, or antigen-antibodies. The inherent deviation between the Fermi level of the photoanode and the photocathode guarantees a spontaneous power supply for the PEC system. Benefiting from the photoanode and recognition elements, the as-fabricated PEC sensing platform has a strong anti-interference ability and high selectivity. Moreover, the PEC sensor displays a wide linear range of 1 nM-100 µM and a low detection limit of 7.1 × 10-10 M (S/N = 3) based on the relationship between photocurrent signal and SA concentration. Accordingly, this research provides a new and valuable approach to detecting various molecules.
ABSTRACT
Based on two different types of luminescence systems (Ru﹡(bpy)32+/TPA and SnO2 NFs/K2S2O8), a new type of electrochemiluminescence (ECL) immunosensor was prepared, which realized the detection of acute myocardial infarction biomarker cTnI. In this strategy, Ru(bpy)32+, above all, was immobilized on the NH2-MIL-125 as a capture probe. Subsequently, cTnI and SnO2 NFs was bonded to the electrode surface through the interaction between antigen and antibody in turn. During this process, Ru(bpy)32+ and the co-reactant TPA first showed strong and stable ECL emission. As the concentration of cTnI in the test system increased, the signal of SnO2 NFs and the co-reactant K2S2O8 gradually enhanced, indicating self-calibrating mechanism of the assay system. Therefore, the "off-on" ECL immunosensor can be detected in the linear range of 10-5 -104 ng/mL, and the limit of detection (LOD) is 3.39 fg/mL (S/N = 3), respectively. The dual-signal electrochemiluminescence method has the advantages of low cost, simple analysis process, wide detection range and good selectivity, providing a promising analysis protocol for clinical applications.
Subject(s)
Biosensing Techniques , Myocardial Infarction , Biomarkers , Humans , Immunoassay , Luminescent Measurements , Myocardial Infarction/diagnosisABSTRACT
Palladium-cobalt alloy nanoparticles were synthesized and dispersed on carbon black support, aiming to have a less expensive catalyst. Catalytic behaviors of PdCo/C catalyst for the oxidation of hydroquinone (HQ) with H2O2 in aqueous solution were evaluated using high-performance liquid chromatography (HPLC). The results revealed that PdCo/C catalyst had better catalytic activity than an equal amount of commercial Pd/C and Co/C catalysts because of the d-band hybridization between Pd and Co. The effects of pH value, solvent, and various interferents including inorganic and organic compounds on the efficiency of HQ oxidation were further investigated. Furthermore, on the basis of mixed potential theory, comprehensive electrochemical measurements such as the open-circuit potential-time (OCP-t) technique and Tafel plot were efficient to assess the catalytic activity of the catalyst, and the results obtained were consistent with those of HPLC measurements. The efficient HQ oxidation was closely associated with the catalytic activity of PdCo nanoparticles because they accelerated the electron-transfer process and facilitated the generation of OH radicals.
