Utilizing COVID-19 as a Model for Diagnostics Using an Electrochemical Sensor.

This paper reports a rapid and sensitive sensor for the detection and quantification of the COVID-19 N-protein (N-PROT) via an electrochemical mechanism. Single-frequency electrochemical impedance spectroscopy was used as a transduction method for real-time measurement of the N-PROT in an immunosensor system based on gold-conjugate-modified carbon screen-printed electrodes (Cov-Ag-SPE). The system presents high selectivity attained through an optimal stimulation signal composed of a 0.

An electrochemical microfluidic device for non-enzymatic cholesterol determination using a lab-made disposable electrode.

Cholesterol is an important steroid and hormone precursor, and its levels in the blood are associated with risk factors for cardiovascular diseases. In this work, a non-enzymatic methodology for cholesterol determination in serum samples is described. First, a working electrode was constructed using homemade ink and a plastic substrate by a simple dunking process.

Enhancing a SARS-CoV-2 nucleocapsid antigen test sensitivity with cost efficient strategy through a cotton intermembrane insertion.

Lateral flow antigen tests have been widely used in the Covid-19 pandemic, allowing faster diagnostic test results and preventing further viral spread through isolation of infected individuals. Accomplishment of this screening must be performed with tests that show satisfactory sensitivity in order to successfully detect the target protein and avoid false negatives. The aim of this study was to create a lateral flow test that could detect SARS-CoV-2 nucleocapsid protein in low concentrations that were comparable to the limits of detection claimed by existing tests from the market.

Biochar: An environmentally friendly platform for construction of a SARS-CoV-2 electrochemical immunosensor.

Waste management is a key feature to ensure sustainable consumption and production patterns, and to combat the impacts of climate change. In this scenario, the production of biochar from different biomasses results in environmental and economic advantages. In this study, biochar was produced from sugarcane bagasse pyrolysis, to immobilize biomolecules, in order to assemble an electrochemical immunosensor to detect antibodies against SARS-CoV-2.

Selective carbonaceous-based (nano)composite sensors for electrochemical determination of paraquat in food samples.

A novel electrochemical sensor based on activated biochar (AB4) and reduced graphene oxide (rGO) was developed and tested for detection of paraquat (PQ) in food samples. Precursor biochar was obtained by the pyrolysis of water hyacinth biomass at 400, 500, and 600 °C, followed by a chemical activation step using HNO to increase the amount of oxygenated and nitrogenated groups. The modified electrodes (rGO-AB4) were tested in different experimental conditions, and exhibited good response under the optimized conditions, showing linearity from 0.

Label-free aptasensor for p24-HIV protein detection based on graphene quantum dots as an electrochemical signal amplifier.

Human immunodeficiency virus (HIV) is still considered a pandemic, and the detection of p24-HIV protein has an important role in the early diagnosis of HIV in adults and newborns. The accessibility of these trials depends on the price and execution difficulty of the method, which can be reduced using electrochemical methods by using enzymeless approaches, disposable and accurate devices. In this work, graphene quantum dots were acquired by a simple synthesis and employed as an electrochemical signal amplifier and support for the aptamer immobilization through a feasible and stable modification of disposable screen-printed electrodes.

Electrochemical sensor based on biochar and reduced graphene oxide nanocomposite for carbendazim determination.

For the first time, a nanocomposite based on biochar and reduced graphene oxide (rGO) was employed to construct a modified carbon paste electrode and applied for the determination of carbendazim (CBZ). Biochar was obtained by through pyrolysis of Eichhornia crassipes biomass, also known how "Aguapé" at 400 °C. The modified electrode with our nanocomposite proposal shows to be able to preconcentrate CBZ and presented the highest analytical response in comparison to the unmodified electrode and by the electrodes prepared with the proposed materials separately.

A simple enzymeless approach for Paraoxon determination using imidazole-functionalized carbon nanotubes.

This work describes the application of a glassy carbon electrode (GCE) modified with imidazole functionalized carbon nanotubes (CNT-H-IMZ) for Paraoxon (PX) determination in samples of commercial, fresh and 100% orange juice. Homemade multi-walled CNTs were treated according to the Hummers procedure to oxidize graphite and later chemically functionalized with imidazole groups. Modified electrodes with CNT-H-IMZ presented a high peak current of PX reduction and an electrocatalytic effect in comparison to the other electrodes.

A carbon fiber ultramicroelectrode as a simple tool to direct antioxidant estimation based on caffeic acid oxidation.

This work describes the construction and evaluation of carbon fiber ultramicroelectrodes (CF-UMEs) in the voltammetric estimation of the antioxidant capacity of wine and grape samples based on caffeic acid (HCAF) oxidation. For this, lab-made CF-UMEs were constructed using an arrangement of six carbon fibers (7 μm diameters individual) assembled in a glass capillary, and caffeic acid (HCAF) was used as a standard solution. By using the most straightforward 2-electrode cell arrangement (the CF-UME as a working electrode and Ag/AgCl as a reference/auxiliary electrode), voltammetric measurements of a 1.

Nonenzymatic electrochemical sensor based on imidazole-functionalized graphene oxide for progesterone detection.

The modification of electrode surfaces has been the target of study for many researchers in order to improve the analytical performance of electrochemical sensors. Herein, the use of an imidazole-functionalized graphene oxide (GO-IMZ) as an artificial enzymatic active site for voltammetric determination of progesterone (P4) is described for the first time. The morphology and electrochemical performance of electrode modified with GO-IMZ were characterized by scanning electron microscopy and cyclic voltammetry, respectively.

Evaluation of antimony microparticles supported on biochar for application in the voltammetric determination of paraquat.

This work describes the construction and application of carbon paste electrodes modified with biochar and antimony microparticles (SbBCPE) for voltammetric determination of paraquat using a simple and sensitive procedure based on voltammetric stripping analysis. Some parameters such as amount of biochar and antimony used in the composition of the carbon paste and instrumental parameters were examined in detail. Under optimized conditions, an analytical curve was obtained for paraquat determination employing SbBCPE, which showed a linear response ranging from 0.