Amino-Functionalized Laponite Clay Material as a Sensor Modifier for the Electrochemical Detection of Quercetin

Abstract

In this work, an electrode modified with an amino-functionalized clay mineral was used for the electrochemical analysis and quantification of quercetin (QCT). The resulting amine laponite (LaNH2) was used as modifier for a glassy carbon electrode (GCE). The organic–inorganic hybrid material was structurally characterized using X-ray diffraction, Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and CHN elemental analysis. The covalent grafting of the organosilane to the clay backbone was confirmed. The charge on the aminated laponite, both without and with the protonation of NH2 groups, was evaluated via cyclic voltammetry. On the protonated amine (LaNH3+)-modified GCE, the cyclic voltammograms for QCT showed two oxidation peaks and one reduction peak in the range of −0.2 V to 1.2 V in a phosphate buffer–ethanol mixture at pH 3. By using the differential pulse voltammetry (DPV), the modification showed an increase in the electrode performance and a strong pH dependence. The experimental conditions were optimized, with the results showing that the peak current intensity of the DPV increased linearly with the QCT concentration in the range from 2 × 10−7 M to 2 × 10−6 M, leading to a detection limit of 2.63 × 10−8 M (S/N 3). The sensor selectivity was also evaluated in the presence of interfering species. Finally, the proposed aminated organoclay-modified electrode was successfully applied for the detection of QCT in human urine. The accuracy of the results achieved with the sensor was evaluated by comparing the results obtained using UV–visible spectrometry.

Synthesis by Melt-Polymerization of a Novel Series of Bio-Based and Biodegradable Thiophene-Containing Copolyesters with Promising Gas Barrier and High Thermomechanical Properties

“…The FTIR spectra of the copolyesters PTBB, PTHH, and PTB x H y were analyzed, and the results are presented in Figure 1 . The spectra show the characteristic bands of the thiophene ring at 3120 cm −1 , 1570–1580 cm −1 , and 711 cm −1 , which are attributed to C=C, C–H, and C–S stretch bonds, respectively [ 48 , 49 , 50 , 51 ]. The sharp peak of the phenyl ring was observed at 1577–1585 cm −1 and 750 cm −1 , and the methylene groups attached to the THH and TBB units were seen at 2930 and 2865 cm −1 , respectively.…”

Fabrication of an Organofunctionalized Talc-like Magnesium Phyllosilicate for the Electrochemical Sensing of Lead Ions in Water Samples

“…The calibration curve (insert of Figure 12 a) was linear over the studied concentration range, with the equation Ip(A) = 3.6[Pb 2+ ](M) + (2.66 × 10 −6 ) (R 2 = 0.997). The detection limit (D L ) and quantitation limit (Q L ) were calculated from D L = 3 S b /m [ 73 , 74 ], and Q L = 10 S b /m, where S b is the standard deviation of the blank and m is the slope of the calibration curve. D L and Q L were estimated to be 7.45 × 10 −8 M and 24.84 × 10 −8 M, respectively, and the sensitivity of the method of 3.6 µA.µM −1 was obtained.…”