In the present work, ternary mixtures of Acetaminophen, Ascorbic acid and Uric acid were resolved using the Electronic tongue (ET) principle and Cyclic voltammetry (CV) technique. The screen-printed integrated electrode array having differentiated response for the three oxidizable compounds was formed by Graphite, Prussian blue (PB), Cobalt (II) phthalocyanine (CoPc) and Copper oxide (II) (CuO) ink-modified carbon electrodes. A set of samples, ranging from 0 to 500 µmol·L−1, was prepared, using a tilted (33) factorial design in order to build the quantitative response model. Subsequently, the model performance was evaluated with an external subset of samples defined randomly along the experimental domain. Partial Least Squares Regression (PLS) was employed to construct the quantitative model. Finally, the model successfully predicted the concentration of the three compounds with a normalized root mean square error (NRMSE) of 1.00 and 0.99 for the training and test subsets, respectively, and R2 ≥ 0.762 for the obtained vs. expected comparison graphs. In this way, a screen-printed integrated electrode platform can be successfully used for voltammetric ET applications.
This research develops a label-free aptamer biosensor (aptasensor) based on graphite-epoxy composite electrodes (GECs) for the detection of lysozyme protein using Electrochemical Impedance Spectroscopy (EIS) technique. The chosen immobilization technique was based on covalent bonding using carbodiimide chemistry; for this purpose, carboxylic moieties were first generated on the graphite by electrochemical grafting. The detection was performed using [Fe(CN)6]3−/[Fe(CN)6]4− as redox probe. After recording the frequency response, values were fitted to its electric model using the principle of equivalent circuits. The aptasensor showed a linear response up to 5 µM for lysozyme and a limit of detection of 1.67 µM. The sensitivity of the established method was 0.090 µM−1 in relative charge transfer resistance values. The interference response by main proteins, such as bovine serum albumin and cytochrome c, has been also characterized. To finally verify the performance of the developed aptasensor, it was applied to wine analysis.
This research develops aptasensors for Lysozyme protein detection [1] using the Electrochemical Impedance Spectroscopy (EIS) technique which is simple, low-cost and follows the rapid highsensitivity transduction principle to monitor biosensing events that take place at the surface of an electrode; the EIS technique is also capable of showing responses at a very low concentration level [2]. To achieve the main objective of this work, electrodes based on Graphite-Epoxy Composite (GECs) were constructed. The chosen immobilization technique was covalent bond using carbodiimide chemistry; for this purpose, carboxylic moieties were first generated on the graphite by electrochemical grafting.The detection is performed using [Fe(CN)6] 3− /[Fe(CN)6] 4− as the redox marker. After recording the frequency response, values are fitted to its electric model; for this purpose, a nonlinear leastsquares regression protocol with complex arithmetic using Z-view is performed using the principles of the equivalent circuit. The aptasensor showed a linear response range of 0.25 μM-5 μM for Lysozyme and a limit of detection (LOD) of 0.19 μM. The sensitivity of the method established was 0.0889 μM −1 in relative charge transfer resistance values.The aptasensor can be regenerated by breaking the complex formed between the aptamer and Lysozyme using 2.0 M NaCl solution at 42 °C, showing its operation for five cycles. The main proteins' interference response, such as bovine serum albumin (BSA) and Cytochrome c (Cyt c), has also been characterized. To finally verify the performance of the developed aptasensor, it was applied to wine analysis. The developed aptasensors indicate their suitability given that they can detect Lys in a complex matrix such as wine obtaining recovery yields of 77%.
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