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In this study, a novel, cost-effective, and environmental-friendly acetylcholinesterase (AChE)-based electrochemical biosensor was developed and utilized for paraoxon-ethyl (PE) detection. In this biosensor, cerium oxide (CeO2) and poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) (PESOT:PSS) modified paper electrode was fabricated by a simple dip-coating method. The synergistic effect of CeO2 and PEDOT:PSS enhance the performance of AChE-based biosensor in terms of sensitivity and selectivity. The electrical conductivity and stability of the fabricated electrode are further improved with the treatment of ethylene glycol (EG). EG decreases the coulombic interactions between PEDOT and PSS molecules, causes polymer chain reorientation, and improves the non-covalent interaction between cellulose molecules and PEDOT, which further leads to higher conductivity. All electrochemical results validate that the biosensor shows good selectivity (Kselectivity < 1), high sensitivity of 52.10 µA/nM, and a low detection limit of 0.12 nM. The accuracy and applicability of the proposed biosensor were also checked with two real samples. All results validate that the fabricated paper electrode can be a promising alternative to other conventional electrodes. [ABSTRACT FROM AUTHOR]

A highly sensitive, flexible, cheap, and biodegradable biosensor has been fabricated to detect paraoxon-ethyl (PE) more effectively. In this work, copper oxide (CuO) and poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS)-modified Whatman paper (WP)-based electrode are fabricated and then characterized by using different techniques. For the fabrication of CuO@PEDOT:PSS/WP electrode, firstly, the PEDOT:PSS/WP was optimized by various solvents such as ethylene glycol (EG), 1-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), N,N-dimethyl acetamide (NMA), and glycerol to enhance the conductivity. The EG-treated PEDOT:PSS/WP electrode shows maximum conductivity (1.4 × 10− 2 S cm− 1) among all solvents. Further, the incorporation of CuO enhances the electrochemical performance of proposed biosensor. All electrochemical results validate that the proposed biosensor (AChE/CuO@PEDOT:PSS/WP) shows high sensitivity and low detection limit of 9.1279 µA/nM and 0.42 nM, respectively. The proposed paper electrode can be a highly promising alternative to conventional electrodes that are known to have limited applications due to their high cost and limited flexibility. The accuracy of the proposed biosensor was successfully checked in two real samples, which makes it more applicable for PE detection in real-world scenarios. [ABSTRACT FROM AUTHOR]

A novel CuS grafted PEDOT:PSS conducting paper-based electrochemical immunosensor has been successfully fabricated for the detection of EpCAM antigen. Electrical conductivity is further improved by doping the CuS@PEDOT:PSS/WP electrode with different organic solvents such as N,N-dimethyl formamide (DMF), N,N-dimethyl acetamide (DMA), ethylene glycol (EG) and dimetyl sulfoxide (DMSO). It is observed that DMSO doped conducting paper shows the highest conductivity (6.1 × 10−2 S/cm) among all these solvents. This low cost, biodegradable electrochemical paper-based immunosensor (BSA/anti-EpCAM/EP) possesses a broad linear range from 0.01 pg/mL to 1000 ng/mL for EpCAM antigen detection. The immunosensor is found to have high sensitivity of 104.31 μA pg−1 mL. This conducting paper based immunosensor is further used to detect EpCAM antigen in human serum samples, thereby confirming a cost effective clinical tool over other costly conventional techniques. • An electrochemical paper-based immunosensor has been designed using CuS and PEDOT:PSS. • This low cost and flexible platform may be a promising candidate over other costly conventional electrodes. • It exhibits high sensitivity of 104.31 μA pg−1 mL in broad range of 0.01 pg/mL to 1000 ng/mL, for EpCAM detection. • The clinical applicability and validity has been checked with human serum sample. [ABSTRACT FROM AUTHOR]

In this paper, a novel nanocomposite is chemically synthesized by reinforcing Ag-doped CuO (Ag@CuO) nanoparticles into the matrix of polyaniline (PANI). This nanocomposite is used as a sensing platform for paraoxon-ethyl (PE) detection. The homogeneous distribution of Ag@CuO nanoparticles onto the PANI matrix provides a smooth and dense surface area, further accelerating the transmission of electrons. The synergistic effect of Ag@CuO and PANI matrix is responsible for the outstanding conductivity, biocompatibility, and catalytic power of the proposed biosensor. For the biosensor fabrication, the nanocomposite is electrophoretically deposited onto the surface of the ITO glass substrate and then the acetylcholinesterase (AChE) enzyme is immobilized onto the fabricated electrode surface by using glutaraldehyde as a crosslinking agent. Under all optimized detection conditions, the proposed biosensor (AChE/Ag@CuO/PANI/ITO) shows a broad linear range from 5 to 100 pM with a low detection limit (LOD) of 11.35 pM. All the electrochemical results confirm the high sensitivity (0.5536 μA (pM)−1 cm−2), high selectivity, good reproducibility, and acceptable stability of the proposed biosensor. Moreover, the proposed biosensor is successfully applied for paraoxon-ethyl (PE) detection in three real samples. • Ag@CuO/PANI based nanocomposite is used as sensing platform for paraoxon-ethyl detection. • The incorporation of Ag@CuO into PANI matrix enhances the surface area, catalytic power and conductivity of nanocomposite • The electrophoretic deposition of Ag@CuO/PANI nanocomposite onto ITO glass substrate enhances electrochemical performance • The biosensor shows high linear range (5–100 pM), high sensitivity (0.55 μA (pM)-1 cm-2) and low detection limit (11.35 pM) • Validation with real samples (banana, tomato and soil) shows its good accuracy and applicability for pesticide detection [ABSTRACT FROM AUTHOR]