Smartphone-Based Electrochemical Biosensor for On-Site Nutritional Quality Assessment of Coffee Blends.

This work aimed to develop an easy-to-use smartphone-based electrochemical biosensor to quickly assess a coffee blend's total polyphenols (Phs) content at the industrial and individual levels. The device is based on a commercial carbon-based screen-printed electrode (SPE) modified with multi-walled carbon nanotubes (CNTs) and gold nanoparticles (GNPs). At the same time, the biological recognition element, Laccase from Trametes versicolor, TvLac, was immobilized on the sensor surface by using glutaraldehyde (GA) as a cross-linking agent. The platform was electrochemically characterized to ascertain the influence of the SPE surface modification on its performance. The working electrode (WE) surface morphology characterization was obtained by scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) imaging. All the measurements were carried out with a micro-potentiostat, the Sensit Smart by PalmSens, connected to a smartphone. The developed biosensor provided a sensitivity of 0.12 µA/µM, a linear response ranging from 5 to 70 µM, and a lower detection limit (LOD) of 2.99 µM. Afterward, the biosensor was tested for quantifying the total Phs content in coffee blends, evaluating the influence of both the variety and the roasting degree. The smartphone-based electrochemical biosensor's performance was validated through the Folin-Ciocâlteu standard method.

ASu@MNPs-based electrochemical immunosensor for vitamin D3 serum samples analysis.

We report a new sensitive label-free electrochemical immunosensor to detect Vitamin D3 (25-OHD3) in untreated serum samples. To this aim, a graphite screen printed electrode (SPE) was modified using cysteamine (CYM) functionalized core-shell magnetic nanoparticles (Au@MNPs) then, the 25-OHD3 antibody (AbD) was immobilized via glutaraldehyde crosslinking. The several steps involved in the immunosensor development and 25-OHD3 analysis were monitored by using differential pulse voltammetry (DPV). The developed immunosensor showed a LOD of 2.4 ng mL-1 and a linear range between 7.4 and 70 ng mL-1. The effectiveness of the immunosensor in human serum analysis was assessed by comparing the results obtained with the chemiluminescence-immunoassay (CLIA) reference method. The high sensitivity and excellent agreement with the reference method suggest its potential use as a POCT to monitor hypovitaminosis 25-OHD levels.

Label-free magnetic nanoparticles-based electrochemical immunosensor for atrazine detection.

This work presents the realization of a label-free electrochemical immunosensor for the quick, cheap, and straightforward determination of atrazine. This biodevice is based on developing a technological platform where a gold screen printed electrode (Au-SPE) surface was modified by the electrodeposition of a highly porous gold layer. As an internal probe redox, a Prussian Blue thin layer (PB) was then electrosynthetized onto the modified Au-SPE. Atrazine antibody (Ab-ATZ) was immobilized using G protein-functionalized magnetic nanoparticles (MNPs@protG) to ensure the correct orientation of the antibody to enhance the immunoaffinity. Under optimum experimental conditions, the electrochemical characterization of the developed immunosensor displays a linearity range towards atrazine within 0.05-1.5 ng/mL, a LOD of 0.011 ng/mL good reproducibility and stability. The immunosensor was tested in the analysis of spiked drinking water samples with a mean recovery ranging from 95.7 to 108.4%. The overall good analytical performances of this immunodevice suggest its application for the screening and monitoring of atrazine in real matrices.

Metal Oxide Nanoparticle Based Electrochemical Sensor for Total Antioxidant Capacity (TAC) Detection in Wine Samples.

A single-use electrochemical screen-printed electrode is reported based on biomimetic properties of nanoceria particles (CeNPs). The developed tool showed an easy approach compared to the classical spectrophotometric methods reported in literature in terms of ease of use, cost, portability, and unnecessary secondary reagents. The sensor allowed the detection of the total antioxidant capacity (TAC) in wine samples. The sensor has been optimized and characterized electrochemically and then tested with antioxidant compounds occurred in wine samples. The electrochemical CeNPs modified sensor has been used for detection of TAC in white and red commercial wines and the data compared to the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS)-based spectrophotometric method. Finally, the obtained results have demonstrated that the proposed sensor was suitable for the simple and quick evaluation of TAC in beverage samples.