The spike protein of SARS-CoV-2 can be detected by electrochemical impedance spectroscopy using antibody desorption from iron magnetic nanoparticles.

SARS-CoV-2 is a matter of concern. Here, biosensors were prepared using iron magnetic nanoparticles containing antibodies against the receptor binding domain (RBD) of the spike protein. Antibodies were adsorbed to nanoparticles in three configurations, including direct adsorption without functionalization (DANPs).

Removal of p-cresol using wash waters from lipopeptide production.

This work shows the efficiency of wash waters from lipopeptide production as a remediation strategy to treat urban water samples contaminated with p-cresol. The harvesting step in surfactin production involved a centrifugation step, generating a major soluble fraction and a fraction that is adsorbed to the biomass. The adsorbed fraction was recovered by washing steps.

Residual biomass from surfactin production is a source of arginase and adsorbed surfactin that is useful for environmental remediation.

Lipopeptides are important secondary metabolites produced by microbes. They find applications in environmental decontamination and in the chemical, pharmaceutical and food industries. However, their production is expensive.

Optical paper-based sensor for ascorbic acid quantification using silver nanoparticles.

In this paper, we demonstrate for the first time the use of silver nanoparticles (AgNPs) for colorimetric ascorbic acid (AA) quantification in a paper-based sensor. This device is constituted by spot tests modified with AgNPs and silver ions bordered by a hydrophobic barrier which provides quantitative and fast analysis of AA. In addition, this device is employed as point-of-care monitoring using a unique drop of the sample.

The use of a graphite-castor oil polyurethane composite electrode for the determination of hydroquinone in photographic developers.

The performance of a new graphite-castor oil polyurethane composite electrode in the determination of hydroquinone in photographic developers in a differential pulse voltammetric (DPV) procedure is described. The 60% (graphite, w/w) composite electrode presented good stability, repeatability and accurate response. Limit of detection of 934 nmol L(-1) was observed for hydroquinone within a linear dynamic range from 66 to 530 nmol L(-1).

Electrochemical detection of cysteine in a flow system based on reductive desorption of thiols from gold.

A simple strategy for cysteine determination using flow-injection analysis with electrochemical detection is described. The approach is based on the chemisorptions reactions of the sulfur moiety of cysteine upon polycrystalline gold electrodes and its subsequent reductive desorption. The electrochemical measurements were accomplished by the application of differential pulse voltammetry (DPV) for the operational optimization and pulsed electrochemical detection (PED) in combination with flow-injection analysis for the electrochemical detection as time function.

Surface plasmon resonance immunosensor for human cardiac troponin T based on self-assembled monolayer.

The cardiac troponin T (cTnT) is specific biomarker important for trials of acute myocardial infarctions (AMI). In this paper, a SPR sensor in real time to detect the biomarker was developed on a commercially available surface plasmon resonance AUTOLAB SPIRIT. The cTnT receptor molecule was covalently immobilized on a gold substrate via a self-assembled monolayer (SAM) of thiols by using cysteamine-coupling chemistry.