Determination of Anthracene on Ag-Au Alloy Nanoparticles/Overoxidized-Polypyrrole Composite Modified Glassy Carbon Electrodes

A novel electrochemical sensor for the detection of anthracene was prepared by modifying a glassy carbon electrode (GCE) with over-oxidized polypyrrole (PPyox) and Ag-Au (1:3) bimetallic nanoparticles (Ag-AuNPs). The composite electrode (PPyox/Ag-AuNPs/GCE) was prepared by potentiodynamic polymerization of pyrrole on GCE followed by its overoxidation in 0.1 M NaOH. Ag-Au bimetallic nanoparticles were chemically prepared by the reduction of AgNO3 and HAuCl4 using C6H5O7Na3 as the reducing agent as well as the capping agent and then immobilized on the surface of the PPyox/GCE. The nanoparticles were characterized by UV-visible spectroscopy technique which confirmed the homogeneous formation of the bimetallic alloy nanoparticles. Transmission electron microscopy showed that the synthesized bimetallic nanoparticles were in the range of 20–50 nm. The electrochemical behaviour of anthracene at the PPyox/Ag-AuNPs/GCE with Ag: Au atomic ratio 25:75 (1:3) exhibited a higher electrocatalytic effect compared to that observed when GCE was modified with each constituent of the composite (i.e., PPyox, Ag-AuNPs) and bare GCE. A linear relationship between anodic current and anthracene concentration was attained over the range of 3.0 × 10−6 to 3.56 × 10−4 M with a detection limit of 1.69 × 10−7 M. The proposed method was simple, less time consuming and showed a high sensitivity

Aptameric Recognition-Modulated Electroactivity of Poly(4-Styrenesolfonic Acid)-Doped Polyaniline Films for Single-Shot Detection of Tetrodotoxin

The work being reported is the first electrochemical sensor for tetrodotoxin (TTX). It was developed on a glassy carbon electrodes (C) that was modified with poly(4-styrenesolfonic acid)-doped polyaniline film (PANI/PSSA). An amine-end functionalized TTX-binding aptamer, 5′-NH2-AAAAATTTCACACGGGTGCCTCGGCTGTCC-3′ (NH2-Apt), was grafted via covalent glutaraldehyde (glu) cross-linking. The resulting aptasensor (C//PANI+/PSSA-glu-NH2-Apt) was interrogated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in sodium acetate buffer (NaOAc, pH 4.8) before and after 30 min incubation in standard TTX solutions. Both CV and EIS results confirmed that the binding of the analyte to the immobilized aptamer modulated the electrochemical properties of the sensor: particularly the charge transfer resistance (Rct) of the PANI+/PSSA film, which served as a signal reporter. Based on the Rct calibration curve of the TTX aptasensor, the values of the dynamic linear range (DLR), sensitivity and limit of detection (LOD) of the sensor were determined to be 0.23–1.07 ng·mL−1 TTX, 134.88 ± 11.42 Ω·ng·mL−1 and 0.199 ng·mL−1, respectively. Further studies are being planned to improve the DLR as well as to evaluate selectivity and matrix effects in real samples

AC voltammetric transductions and sensor application of a novel dendritic poly(propylene thiophenoimine)-co-poly(3-hexylthiophene) star co-polymer

The contamination of surface and underground water by polyaromatic hydrocarbons (PAHs), such asphenanthrene, presents significant latent risk to humans and the ecosystem through the food chain. Oneof the sources of PAH pollution is the activities of the oil industry. A novel dendritic star-copolymer sensorsystem (Au|G3PPT-co-P3HT) for the determination of phenanthrene (PHE) in oil-polluted wastewater wasprepared by in situ electrochemical co-polymerization of generation 3 poly(propylene thiophenoimine)(G3PPT) and poly(3-hexylthiophene) (P3TH) on a gold electrode. Electrochemical characterization and sensor application of the Au|G3PPT-co-P3HT electrode were performed by alternating current voltammetry (ACV), in a supporting electrolyte of 0.1 M Bu4NClO4in acetonitrile. The sensor parameters includea dynamic linear range (DLR) of application values of 2.78-7.65 nM and a limit of detection (LOD) of1.42 nM (0.253 ppb). The WHO guideline value for PAHs is 0.7 ppb, which falls within the DLR of thedendrimeric sensor for PHE. The Au|G3PPT-co-P3HT was sensitive to PHE determination in oil-polluted wastewater.