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.

X-Ray Photoelectron Spectroscopic Characterization of Chemically Modified Electrodes Used as Chemical Sensors and Biosensors: A Review

“…At last, FWHM and SoS values used in curve fittings should always be reported (see [69] for a good example) but this is rarely done. Canevari et al [104] and Fernandes et al [108] are appreciable examples of correctly reporting the results of XPS curve fittings.…”

“…Canevari et al described the preparation of a hybrid material composed of disordered mesoporous silica modified with multiwalled carbon nanotubes [104]. The material was characterized by N2 adsorption-desorption isotherms, XRD, FESEM, HRTEM, Raman and XPS techniques.…”

Synthesis and characterization of α-nickel (II) hydroxide particles on organic-inorganic matrix and its application in a sensitive electrochemical sensor for vitamin D determination

“…The hybrid material was prepared according to the following procedure [1]: TEOS (0.009 mol) was mixed with ethanol in the proportion 1/1 (v/v) and the solution was left stirring for 10 min. Then, 180 mg of graphene oxide was added together with 0.8 mL of H 2 O and the suspension was kept stirring for more 10 min.…”

“…The synergism that occurs between different components of the hybrid material improves its properties in comparison to each isolated one and, thus, increases its potential as well as its applications in several fields. In this way, hybrid organic-inorganic materials based on silica-containing carbon allotropes have long been used as a basis to support the development of electrochemical sensors, due to their high chemical stability, robustness, functional groups presence and excellent electrochemical properties [1,2].…”

A Sensitive and Selective Electrochemical Method for the Simultaneous Determination of Dopamine and Paracetamol based on a Multiwalled Carbon Nanotubes/Poly(l-lysine)-modified Glassy Carbon Electrode

“…According to Table S1, it is clear that the modified electrode developed in this study has a lower detection limit than some of the reported modified electrodes, 11,1416 while the linear dynamic range of the present study is also better than the values reported in most earlier studies. 2,13 The fabrication reproducibility for three MWCNTs/PLL/ GCE was investigated by comparing the oxidation peak current of 20.0¯M DA and PA. The relative standard deviation (RSD%) values in five replicate measurements using three different electrodes were 3.4% (for DA) and 3.8% (for PA).…”