Ionic-Liquid-Stabilized TiO₂ Nanostructures: A Platform for Detection of Hydrogen Peroxide

Hydrogen peroxide (H₂O₂) acts as a signaling molecule to direct different biological processes. However, its excess amount results in oxidative stress, which causes the onset of different types of cancers. TiO₂ nanostructure was synthesized by a facile hydrothermal method. The prepared material was characterized by FTIR spectroscopy, XRD, SEM, EDX, TGA, and Raman spectroscopy, which confirmed the formation of nanostructured material. Subsequently, the prepared nanoparticles (NPs) were capped with 1-H-3-methylimidazolium acetate ionic liquid (IL) to achieve its deagglomeration and functionalization. A new colorimetric sensing probe was prepared for the detection of H₂O₂ based on ionic liquid-capped TiO₂ nanoparticles (TiO₂/IL) and 3,3',5,5'-tetramethylbenzidine (TMB) dye, which acts as an oxidative chromogenic substrate. H₂O₂ reacts with TMB, in the presence of ionic liquid-coated TiO₂ NPs, to form a blue-green product. The color was visualized with the naked eye, and the colorimetric change was confirmed by a UV-vis spectrophotometer. To obtain the best response of the synthesized sensor, different parameters (time, pH, concentrations, loading of nanomaterials) were optimized. It showed a low limit of detection 8.61 × 10^-8 M, a high sensitivity of 2.86 × 10^-7 M, and a wide linear range of 1 × 10^-9-3.6 × 10^-7 M, with a regression coefficient (R ²) value of 0.999. The proposed sensor showed a short incubation time of 4 min. The sensing probe did not show any interference from the coexisting species. The TiO₂/IL sensor was effectively used for finding H₂O₂ in the urine samples of cancer patients.