In this work, efforts have been made to develop a conducting paper‐ (CP) based biosensor using poly(3,4ethylenedioxythiophene): poly(4‐styrene sulfonate) (PEDOT:PSS)‐grafted reduced graphene oxide‐titanium dioxide (rGO‐TiO2) nanohybrid. The effect of different dopant (ethylene glycol [EG], glycerine and methanol) on the conductivity of the paper has been investigated, and it was observed that the conductivity of the CP significantly increases from 6.9 × 10−5 S/cm to 1.1 × 10−4 S/cm on treatment with EG. While, after the incorporation rGO‐TiO2 nanohybrid into PEDOT:PSS‐grafted paper, the conductivity increased to 4.9 × 10−2 S/cm. The fabricated flexible rGO‐TiO2@CP was characterized using X‐ray diffraction, Thermogravimetric analysis, scanning electron microscopy, FTIR spectroscopy, and amperometric techniques. The developed rGO‐TiO2@CP has been utilized for the immobilization of glucose oxidase for the quantitative estimation of glucose. Electrochemical results reveal that the modified CP shows high sensitivity (94.98 μAmM−1 cm−2) with a low limit of detection (0.01 mM) and can be a promising substitute over other expensive conventional electrodes.

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A metal-free, enzymatic biosensor was developed using graphitic carbon nitride (g-C3N4)-wrapped poly-ortho-phenylenediamine (PoPD) for the determination of xanthine (Xn). Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction confirmed the successful formation of the PoPD, g-C3N4 nanosheets and PoPD@g-C3N4 nanocomposite. Furthermore, the electrochemical behavior of the biosensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The prepared enzyme electrode exhibited maximum response at pH 7.5 with a response time of 5 s, and its sensitivity was 5.798 μAM–1. The nanocomposite shows exceptional sensing capabilities for detecting Xn, having a wide linear range from 1 nM to 1 μM with a relatively low detection limit of 0.001 nM. The biosensor shows good stability (4 weeks) and reproducibility and can detect the presence of Xn from other interfering analytes. Validation of the biosensor with real samples obtained from Rohu (Labeo rohita) fish shows that the fabricated biosensor has the requisite potential to be used for Xn detection in meat samples.

Phenolic compounds (PhCs) are ubiquitously distributed phytochemicals found in many plants, body fluids, food items, medicines, pesticides, dyes, etc. Many PhCs are priority pollutants that are highly toxic, teratogenic, and carcinogenic. Some of these are present in body fluids and affect metabolism, while others possess numerous bioactive properties such as retaining antioxidant and antimicrobial activity in plants and food products. Therefore, there is an urgency for developing an effective, rapid, sensitive, and reliable tool for the analysis of these PhCs to address their environmental and health concern. In this context, carbonaceous nanomaterials have emerged as a promising material for the fabrication of electrochemical biosensors as they provide remarkable characteristics such as lightweight, high surface: volume, excellent conductivity, extraordinary tensile strength, and biocompatibility. This review outlines the current status of the applications of carbonaceous nanomaterials (CNTs, graphene, etc.) based enzymatic electrochemical biosensors for the detection of PhCs. Efforts have also been made to discuss the mechanism of action of the laccase enzyme for the detection of PhCs. The limitations, advanced emerging carbon-based material, current state of artificial intelligence in PhCs detection, and future scopes have also been summarized.