Digitally Controlled Printing of Bioink Barriers for Paper-Based Analytical Devices: An Environmentally Friendly One-Step Approach.

The patterning of hydrophilic paper with hydrophobic materials has emerged as an interesting method for the fabrication of paper-based devices (PADs). Herein, we demonstrate a digitally automated, easy, low-cost, eco-friendly, and readily available method to create highly hydrophobic barriers on paper that can be promptly employed with PADs by simply using a bioink made with rosin, a commercially available natural resin obtained from conifer trees. The bioink can be easily delivered with the use of a ballpoint pen to produce water- and organic solvent-resistant barriers, showing superior properties when compared to other methods such as wax-printing or permanent markers.

Fabrication of paper-based analytical devices using stencil-printed glass varnish barriers for colorimetric detection of salivary α-amylase.

Background: Developing disposable paper-based devices has positively impacted analytical science, particularly in developing countries. Some benefits of those devices include their versatility, affordability, environmentally friendly, and the possibility of being integrated with portable electrochemical or colorimetric detectors. Paper-based analytical devices (PADs) comprising circular zones and microfluidic networks have been successfully employed in the analytical chemistry reign.

Occupational Stress Monitoring Using Biomarkers and Smartwatches: A Systematic Review.

This article presents a systematic review of the literature concerning scientific publications on wrist wearables that can help to identify stress levels. The study is part of a research project aimed at modeling a stress surveillance system and providing coping recommendations. The investigation followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Electromembrane Extraction of Naphthenic Acids in Produced Water Followed by Ultra-High-Resolution Mass Spectrometry Analysis.

Naphthenic acids comprise one of the most toxic compounds of the produced water released from offshore oil platforms. Therefore, developing and applying faster, simpler, and more efficient analytical methods for analyzing naphthenic acids are urgently needed. Electromembrane extraction (EME) uses the electrokinetic migration of target ions through a porous membrane.

Plug-and-play assembly of paper-based colorimetric and electrochemical devices for multiplexed detection of metals.

Heavy metals are the main pollutants present in aquatic environments and their presence in human organisms can lead to many different diseases. While many methods exist for analysis, colorimetric and electrochemistry are particularly attractive for on-site analysis and their integration on a single platform can improve multiplexed metals analysis. This report describes for the first time a "plug-and-play" (PnP) assembly for coupling a microfluidic paper-based device (μPAD) and a screen-printed electrochemical paper-based device (ePAD) using a vertical and reversible foldable mechanism for multiplexed detection of Fe, Ni, Cu, Zn, Cd and Pb in river water samples.

Biomimetic electrochemical sensors: New horizons and challenges in biosensing applications.

The urge to meet the ever-growing needs of sensing technology has spurred research to look for new alternatives to traditional analytical methods. In this scenario, the glucometer is the flagship of commercial electrochemical sensing platforms, combining selectivity, reliability and portability. However, other types of enzyme-based biosensors seldom achieve the market, in spite of the large and increasing number of publications.

Enzymatic Electroanalytical Biosensor Based on Fungus for Detection of Phytomarkers in Infusions and Green Tea Kombucha.

In this work, we developed an enzymatic voltammetric biosensor for the determination of catechin and gallic acid in green tea and kombucha samples. The differential pulse voltammetry (DPV) methodology was optimized regarding the amount of crude enzyme extract, incubation time in the presence of the substrates, optimal pH, reuse of the biosensor, and storage time. Samples of green tea and kombucha were purchased in local markets in the city of Goiânia-GO, Brazil.

Environmentally Friendly Manufacturing of Flexible Graphite Electrodes for a Wearable Device Monitoring Zinc in Sweat.

Electrochemical sensors based on graphite and polymers have emerged as powerful analytical tools for bioanalytical applications. However, most of the fabrication processes are not environmentally friendly because they often involve the use of toxic reagents and generate waste. This study describes an alternative method to produce flexible electrodes in plastic substrates using graphite powder and thermal laminating sheets by solid-solid deposition through hot compression, without the use of hazardous chemical reagents.

Functionalized polyacrylamide as an acetylcholinesterase-inspired biomimetic device for electrochemical sensing of organophosphorus pesticides.

A plethora of publications has continuously reported electrochemical biosensors for detection of pesticides. However, those devices rarely accomplish commercial application due to technical issues associated with the lack of stability and high cost of the biological recognition element (enzyme). Alternatively, the biomimetic catalysts have arisen as a candidate for application in electrochemical biosensors to overcome the enzymatic drawbacks, combining low cost scalable materials with superior stability.

Sensitive determination of carbendazim in orange juice by electrode modified with hybrid material.

This paper describes the application of a glassy carbon electrode modified with a thin film of mesoporous silica/multiwalled carbon nanotubes for voltammetric determination of the fungicide carbendazim (CBZ). The hybrid material, (SiO2/MWCNT), was obtained by a sol-gel process using HF as the catalyst. The amperometric response to CBZ was measured at +0.

On the behavior of acetylcholinesterase immobilized on carbon nanotubes in the presence of inhibitors.

The behavior of acetylcholinesterase before and after click-chemistry reaction on carbon nanotubes was evaluated by kinetic parameters from Michaelis-Menten equation. These data were obtained by means of UV-vis absorption for the enzyme in solution and attached to MWCNTs under two experimental conditions involving the presence or absence of enzyme inhibitors (chlorpyrifos and paraoxon pesticides). After the immobilization step it was possible to obtain, from Michaelis-Menten equation, Km values comparable to those for free enzyme, suggesting that the immobilization procedure does not affect the enzyme-substrate interaction.