Efficient Preparation of a Nonenzymatic Nanoassembly Based on Cobalt-Substituted Polyoxometalate and Polyethylene Imine-Capped Silver Nanoparticles for the Electrochemical Sensing of Carbofuran

Abstract

The ever-growing exploitation of pesticides and their lethal effects on living beings have made it a dire need of the day to develop an accurate and reliable approach for their monitoring at trace levels. The designing of an enzyme-free electrocatalyst to electrochemically detect the pesticide residues is currently gaining much importance. In this study, a novel redox-sensing film was constructed successfully based on cobalt-substituted Dawson-type polyoxometalate [P 2 W 17 O 61 (Co 2+ ·OH 2 )] 7– (Co-POM) and polyethylene imine (PEI)-capped silver nanoparticles (AgNPs). A nanohybrid assembly was fabricated on a glassy carbon electrode’s surface by alternately depositing Co-POM and PEI-AgNPs using the layer-by-layer self-assembly method. The surface morphology of the immobilized CoPOM/AgNP multilayer nanoassembly was analyzed through scanning electron microscopy along with energy-dispersive spectroscopy for elemental analysis. The redox properties and surface morphologies of fabricated assemblies were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The practicability and feasibility of the proposed sensing layer was tested for the detection of a highly toxic insecticide, that is, carbofuran. The fabricated sensor exhibited a limit of detection of 0.1 mM with a sensitivity of 13.11 μA mM –1 for carbofuran. The results depicted that the fabricated nonenzymatic hybrid film showed excellent electrocatalytic efficiency for the carbofuran oxidation. Furthermore, the obtained value of “apparent Km”, that is, 0.4 mM, illustrates a good electro-oxidation activity of the sensor for the detection of carbofuran. The exceptionally stable redox activity of Co-POM, high surface area and greater conductivity of AgNPs, and the synergistic effect of all components of the film resulted in an excellent analytical performance of the proposed sensing assembly. This work provides a new direction to the progress and designing of nonenzymatic electrochemical sensors for pesticide determination in real samples.

Layer‐by‐Layer Construction of Hybrid Film Based on PEI Polymer and Preyssler‐Type Polyoxometalates: Its Electrochemical and Quartz Crystal Microbalance Measurement

“…In the circuit, R S is in series with C dl while C dl is parallel with Z W and R ct , which is together known as a diffusional branch. Because of the nonideal interfacial features of the electrode surface, C dl is replaced with a constant phase element (CPE) [8] . Given by, CPE=−1/(Ciω)n, where C is the capacitance, which describes the charge separation at the double layer interface, ω is the frequency in rad s −1 and the n exponent is due to the heterogeneity of the surface.…”

“…Because of the nonideal interfacial features of the electrode surface, C dl is replaced with a constant phase element (CPE). [8] Given by, CPE = À 1/(Ciω)n, where C is the capacitance, which describes the charge separation at the double layer interface, ω is the frequency in rad s À 1 and the n exponent is due to the heterogeneity of the surface. The CPE is closely related to the porosity and roughness of electrodes.…”

“…Polyoxometalates (POMs) are a significant class of inorganic metal oxide nanoclusters possessing a wide domain of structure and abundant elemental compositions. [1][2][3] POM's versatile properties, including stable redox states and the ability to undergo multi-electron redox processes with negligible structural changes, enable them to be employed across a large spectrum of applications, such as catalysis, [4] energy, [5] memory, [6] optics, [7] sensor, [8] magnetism [9] and bioapplications. [10] POM architectures are mostly formed by the condensation of oxygen atoms and early transition metals most commonly vanadium (V), [11] molybdenum (Mo) [12] tungsten (W), [13] and less commonly niobium (Nb) [14] and tantalum (Ta) [15] or a mixture of these elements in their higher oxidation states.…”

Nanomaterials in electrochemical nanobiosensors of miRNAs

“…By controlling the size and shape of AgNPs, they can help with label-free detection and more sensitive and amplified responses to various novel electrochemical sensing platforms. 103,104 The miRNA sensors developed based on this technology are reviewed in Table 5. In 2018, Gao et al constructed a novel electrochemical nanobiosensor to simultaneously determine miR-16 and alpha-fetoprotein (AFP) as hepatocellular carcinoma (HCC) diagnostic biomarkers.…”

Activated porous carbon supported Pd and ZnO nanocatalysts for trace sensing of carbaryl pesticide in water and food products

“…3 Pesticide residues impart serious hazards to human and non-target organisms and compromise the sustainability of the environment. 4 Among a large number of pesticides, carbaryl is the most widely used insecticide that shows a broad spectrum of activity and application. Carbaryl is the common name for the chemical, carbamic acid derivative 1-naphthyl N -methylcarbamate, which belongs to the carbamate pesticides class.…”