Employing electrochemically derived pH gradients for Lab-on-PCB protein preconcentration devices.

Protein preconcentration is an essential sample preparation step for analysis in which the targeted proteins exist in low concentrations, such as bodily fluids, water, or wastewater. Nonetheless, very few practical implementations of miniaturized protein preconcentration devices have been demonstrated in practice, and even fewer have been integrated with other microanalytical steps. Existing approaches rely heavily on additional chemicals and reagents and introduce complexity to the overall assay. In this paper, we propose a novel miniaturized isoelectric focusing-based protein preconcentration screening device based on electrochemically derived pH gradients rather than existing chemical reagent approaches. In this way, we reduce the need for additional chemical reagents to zero while enabling device incorporation in a seamlessly integrated full protein analysis microsystem via Lab-on-PCB technology. We apply our previously presented Lab-on-PCB approach to quantitatively control the pH of a solution in the vicinity of planar electrodes using electrochemical acid generation through redox-active self-assembled monolayers. The presented device comprises a printed circuit board with an array of gold electrodes that were functionalized with 4-aminothiophenol; this formed a self-assembled monolayer that was electropolymerized to improve its electrochemical reversibility. Protein preconcentration was performed in two configurations. The first was open and needed the use of a holder to suspend a well of fluid above the electrodes; the second used microfluidic channels to enclose small volumes of fluid. Reported here are the resulting data for protein preconcentration in both these forms, with a quantitative concentration factor shown for the open form and qualitative proof shown for the microfluidic.

Integrated Electrochemical Biosensors for Detection of Waterborne Pathogens in Low-Resource Settings.

More than 783 million people worldwide are currently without access to clean and safe water. Approximately 1 in 5 cases of mortality due to waterborne diseases involve children, and over 1.5 million cases of waterborne disease occur every year. In the developing world, this makes waterborne diseases the second highest cause of mortality. Such cases of waterborne disease are thought to be caused by poor sanitation, water infrastructure, public knowledge, and lack of suitable water monitoring systems. Conventional laboratory-based techniques are inadequate for effective on-site water quality monitoring purposes. This is due to their need for excessive equipment, operational complexity, lack of affordability, and long sample collection to data analysis times. In this review, we discuss the conventional techniques used in modern-day water quality testing. We discuss the future challenges of water quality testing in the developing world and how conventional techniques fall short of these challenges. Finally, we discuss the development of electrochemical biosensors and current research on the integration of these devices with microfluidic components to develop truly integrated, portable, simple to use and cost-effective devices for use by local environmental agencies, NGOs, and local communities in low-resource settings.