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.