title: Sol-gel thin-film based mesoporous silica and carbon nanotubes for the determination of dopamine, uric acid and paracetamol in urine.
abstract: This work describes the preparation, characterization and application of a hybrid material composed of disordered mesoporous silica (SiO2) modified with multiwalled carbon nanotubes (MWCNTs), obtained by the sol-gel process using HF as the catalyst. This hybrid material was characterized by N2 adsorption-desorption isotherms, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HR-TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This new hybrid material was used for the construction of a thin film on a glassy carbon electrode. The modified electrode using this material was designated SiO2/MWCNT/GCE. The electrocatalytic properties of the electrode toward dopamine, uric acid and paracetamol oxidation were studied by differential pulse voltammetry. Well-defined and separated oxidation peaks were observed in phosphate buffer solution at pH 7.0, in contrast with the ill-defined peaks observed with unmodified glassy carbon electrodes. The electrode had high sensitivity for the determination of dopamine, uric acid and paracetamol, with the limits of detection obtained using statistical methods, at 0.014, 0.068 and 0.098 µmol L(-1), respectively. The electrode presented some important advantages, including enhanced physical rigidity, surface renewability by polishing and high sensitivity, allowing the simultaneous determination of these three analytes in a human urine sample.
authors.affiliation: Institute of Chemistry, State University of São Paulo, PO Box 780, 13560-970 São Carlos, SP, Brazil. Electronic address: tccanevari@gmail.com.
authors.forename: Thiago C
authors.initials: TC
authors.lastname: Canevari
authors.forename: Paulo A
authors.initials: PA
authors.lastname: Raymundo-Pereira
authors.forename: Richard
authors.initials: R
authors.lastname: Landers
authors.forename: Edilson V
authors.initials: EV
authors.lastname: Benvenutti
authors.forename: Sérgio A S
authors.initials: SA
authors.lastname: Machado
mesh_terms: D000082:Acetaminophen / Q000652:urine*; D004298:Dopamine / Q000652:urine*; D055664:Electrochemical Techniques; D004566:Electrodes; D006801:Humans; D006858:Hydrofluoric Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D008855:Microscopy, Electron, Scanning; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D044367:Phase Transition; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D014527:Uric Acid / Q000652:urine*
chemical_list: D037742:Nanotubes, Carbon; D014527:Uric Acid; D000082:Acetaminophen; D012822:Silicon Dioxide; D006858:Hydrofluoric Acid; D004298:Dopamine
keywords: Carbon nanotubes; Dopamine; Electrochemical sensor; Mesoporous silica; Paracetamol; Uric acid