Co-Doped CeO(2)/Activated C Nanocomposite Functionalized with Ionic Liquid for Colorimetric Biosensing of H(2)O(2) via Peroxidase Mimicking

Hydrogen peroxide acts as a byproduct of oxidative metabolism, and oxidative stress caused by its excess amount, causes different types of cancer. Thus, fast and cost-friendly analytical methods need to be developed for H(2)O(2). Ionic liquid (IL)-coated cobalt (Co)-doped cerium oxide (CeO(2))/activated carbon (C) nanocomposite has been used to assess the peroxidase-like activity for the colorimetric detection of H(2)O(2). Both activated C and IL have a synergistic effect on the electrical conductivity of the nanocomposites to catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB). The Co-doped CeO(2)/activated C nanocomposite has been synthesized by the co-precipitation method and characterized by UV–Vis spectrophotometry, FTIR, SEM, EDX, Raman spectroscopy, and XRD. The prepared nanocomposite was functionalized with IL to avoid agglomeration. H(2)O(2) concentration, incubation time, pH, TMB concentration, and quantity of the capped nanocomposite were tuned. The proposed sensing probe gave a limit of detection of 1.3 × 10(−8) M, a limit of quantification of 1.4 × 10(−8) M, and an R(2) of 0.999. The sensor gave a colorimetric response within 2 min at pH 6 at room temperature. The co-existing species did not show any interference during the sensing probe. The proposed sensor showed high sensitivity and selectivity and was used to detect H(2)O(2) in cancer patients’ urine samples.