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In this research, an electrochemical PSA (prostate specific antigen) immunosensor based on Nafion/reduced graphene oxide (rGO)/aldehyde methyl pyridine (CHO-MP) composite electrode was newly developed by using noncovalent functionalization of rGO and CHO-MP. Due to improper binding stability of the immobilized antibody, immunosensors may show false positive results. The proposed composite material can provide suitable microenvironment for the immobilized anti-PSA and improve the conductivity of electrode. Furthermore, the used nafion can improve the mechanical and chemical behaviors of the developed immunosensor. Physical characterization of rGO/CHO-MP was observed through XPS, FTIR, and FE-SEM. Under the optimized conditions, the fabricated immunosensor showed a linear range of 0.005-90 ng mL-1, detection limit of 1.6 pg mL-1, excellent selectivity, stability, and reproducibility. Lastly, human serum samples were analyzed and the recovery range was obtained as 95.8% to 107.9% with an RSD of 5.1% (n = 5). These results showed that the as-fabricated sensor is highly promising in clinical applications. [ABSTRACT FROM AUTHOR]

In this study, an environmentally friendly and simple method to synthesize rGO-BiNP nanocompositewas newly developed to address some drawbacks of in-situ Bi plating method for heavy metal ions detection and the synthesized nanocomposite was confirmed using physical and electrochemical analysis. Furthermore, the feasibility of Cd ions detection by the synthesized nanocomposite was confirmed using square-wave anodic stripping voltammetry (SWASV) without in-situ Bi plating, which can change the pH value of test solution and the sensing results. Therefore, the fabricated sensor can directly test target solution without pre-treatment. Under the optimal conditions, the sensitivity for Cd ions was 49 nA/ppb and the correlation coefficient was 0.983, respectively. The limit of detection was 0.3 ppb for Cd ions for a short deposition time of 150 s. The fabricated sensor exhibited linear response to Cd ions in the concentration range from 10 ppb to 120 ppb with good linearity. The determination efficiency toward Cd ions was significantly enhanced by the synthesized rGO-BiNP coated working electrode, due to the enlargement of active area and its electrochemical properties. These results indicate a great potential of the rGO-BiNP electrode for electrochemical heavy-metal ion sensor applications. [ABSTRACT FROM AUTHOR]

Here, an ultrasensitive enzymatic electrochemical L-glutamate sensor was successfully developed and characterized using carboxyl terminated reduce graphene oxide (Crbxl-RGO) and Pt nanoparticles as a supporting and catalyzing medium. Crbxl-RGO was drop casted on the Au substrate and Pt nanoparticles were electrodeposited on Crbxl-RGO/Au modified substrate. L-Glutamate dehydrogenase-chitosan (GLDH-chit) composite was immobilized on the sensing area using EDC/NHS bonding material treatment. The physical characteristic of the sensor matrix was monitored through field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS), Energy dispersive spectroscopy (EDX) and analytical characterization was analyzed by using cyclic voltammetry (CV), electrochemical impedance spectroscopy and differential pulse voltammetry (DPV). Under optimized condition the sensor showed sensitivity of 973 ± 4 μA/mMcm2, wide linear range 0.004-0.9 mM and limit of detection 0.1 μM that indicates promising approach for detecting L-glutamate. [ABSTRACT FROM AUTHOR]