In this report, an electrochemical genosensor has been fabricated for Escherichia coli O157:H7 (E. coli) detection using a graphene oxide–nickel ferrite–chitosan (GO/NiF/ch) nanocomposite film as the sensing platform. The prepared GO/NiF/ch nanocomposite was characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and thermo-gravimetric analysis. Nucleic acid hybridization technique was employed for the detection of a specific sequence of E. coli. The hybridization between the complementary DNA and probe DNA was investigated by differential pulse voltammetry (DPV) using methylene blue as redox indicator. The fabricated biosensor exhibits a linear response to complementary DNA in the concentration range of 10⁻⁶ to 10⁻¹⁶ M with a detection limit of 1 × 10⁻¹⁶ M.

A multi-walled carbon nanotube composite electrode incorporating Polyaniline (PANI) and Polyacrylic acid (PAA) is presented by diffusing aniline and PAA into Nafion- MWCNTs membranes supported upon a platinum macrodisc electrode. Nafion is found to be an ideal medium for dispersion of MWCNTs and for the formation of a homogeneous composite. The composite has been characterized utilizing SEM, TEM, FT-IR and electrochemical techniques. Electrochemical characterization reveals that the redox activity of the composite is improved with the cumulative effect of MWCNTs and PAA as additives. The electroanalytical behavior of the composite is evaluated towards the sensing of ascorbic acid in the presence of dopamine and uric acid exhibiting a detection limit of 2.5 × 10⁻⁷ M.

The incorporation of carbon-based nanomaterials in screen-printed electrode sensors has overtaken traditional techniques in biological and environmental sample analysis where immediate on-site monitoring is required. Our review focuses on 1D and 2D biosensor materials.

A highly sensitive electrochemical sensor is reported for glucose detection using carbon nanotubes grown in situ at low temperatures on photolithographically defined gold microelectrode arrays printed on a glass substrate (CNTs/Au MEA). One of the main advantages of the present design is its potential to monitor 64 samples individually for the detection of glucose. The selectivity of the fabricated MEA towards glucose detection is achieved via modification of CNTs/Au MEA by immobilizing glucose oxidase (GO_x) enzyme in the matrix of poly (paraphenylenediamine) (GO_x/poly (p-PDA)/CNTs/Au MEA). The electrocatalytic and electrochemical responses of the proposed sensing platform towards glucose determination were examined via cyclic voltammetry and electrochemical impedance spectroscopy. The developed impedimetric biosensor exhibits a good linear response towards glucose detection, i.e., 0.2–27.5 µM concentration range with sensitivity and detection limits of 168.03 kΩ⁻¹ M⁻¹ and 0.2 ± 0.0014 μM, respectively. The proposed glucose biosensor shows excellent reproducibility, good anti-interference property, and was successfully tested in blood serum samples. Further, the applicability of the proposed sensor was successfully validated through HPLC. These results supported the viability of using such devices for the simultaneous detection of multiple electroactive biomolecules of physiological relevance. Graphical Abstract