Fabrication of a novel tantalum boride/vanadium carbide modified screen-printed carbon electrode for voltammetric determination of pimonidazole in bio-fluids.

For the first time, a tumour hypoxia marker detection has been developed using two-dimensional layered composite modified electrodes in biological and environmental samples. The concept of TaB2 and V4C3-based MXene composite materials is not reported hitherto using ball-milling and thermal methods and it remains the potentiality of the present work. The successful formation is confirmed through various characterisation techniques like X-ray crystallography, scanning electron microscopy photoelectron, and impedance spectroscopy. A reliable and repeatable electrochemical sensor based on TaB2@V4C3/SPCE was developed for quick and extremely sensitive detection of pimonidazole by various electroanalytical methods. It has been shown that the modified electrode intensifies the reduction peak current and causes a decrease in the potential for reduction, in comparison with the bare electrode. The proposed sensor for pimonidazole reduction has strong electrocatalytic activity and high sensitivity, as demonstrated by the cyclic voltammetry approach. Under the optimal experimental circumstances, differential pulse voltammetry techniques were utilised for generating the wide linear range (0.02 to 928.51 µM) with a detection limit of 0.0072 µM. The resultant data demonstrates that TaB2@V4C3/SPCE nano-sensor exhibits excellent stability, reliability, and repeatability in the determination of pimonidazole. Additionally, the suggested sensor was successfully used to determine the presence of pimonidazole in several real samples, such as human blood serum, urine, water, and drugs.

Picomolar level electrochemical detection of hydroquinone, catechol and resorcinol simultaneously using a MoS2 nano-flower decorated graphene.

Herein, a graphene-nano-molybdenum disulphide (pGr-MoS2), synthesized from pulverized graphite and using precursors of MoS2, was investigated for the electrochemical sensing of dihydroxy benzene isomers (DHBI): hydroquinone (HQ), catechol (CA), and resorcinol (RE). Interestingly, the material could sense the three isomers simultaneously, with well-defined peaks and an adequate potential difference between each peak. The detection limits (3σ method) of HQ, CA, and RE on the glassy carbon electrode (GCE) modified with pGr-MoS2 are 10-13, 10-12, and 10-8 M (i.e., 0.1 pM, 1 pM, and 10 nM), respectively, and are the lowest reported so far for the isomers. The pGr-MoS2/GCE exhibited selectivity towards DHBI, in the presence of other toxic contaminants and metal ions such as phenol, dinitrophenol, trinitrophenol, urea and glucose, Hg(II), Ca(II), Ni(II), Zn(II), Cu(II), Na(I) and K(I). A possible mechanism for this superior selectivity of pGr-MoS2 towards DHBI is discussed based on the structural properties of pGr-MoS2 with evidence. Further, the pGr-MoS2 sensor exhibited reproducibility (with six different electrodes), stability (≥90 days), and repeatability properties. The sensing performance was successfully demonstrated in real water samples such as ground-, tap-, and river- water spiked with HQ, CA, and RE.