Abstract
Paper-based microchip electrophoresis has the potential to bring laboratory electrophoresis tests to the point of need. However, high electric potential and current values induce pH and temperature shifts, which may affect biomolecule electrophoretic mobility thus decrease test reproducibility and accuracy of paper-based microfluidic electrophoresis. We have previously developed a microchip electrophoresis system, HemeChip, which has the capability of providing low-cost, rapid, reproducible, and accurate point-of-care (POC) electrophoresis tests for hemoglobin analysis. Here, we report the methodologies we implemented for characterizing HemeChip system pH and temperature during the development process, including utilizing commercially available universal pH indicator and digital camera pH shift characterization, and infrared camera characterizing temperature shift characterization. The characterization results demonstrated that pH shifts up to 1.1 units, a pH gradient up to 0.11 units/mm, temperature shifts up to 40 °C, and a temperature gradient up to 0.5 °C/mm existed in the system. Finally, we report an acid pre-treatment of the separation media, a cellulose acetate paper, mitigated both pH and temperature shifts and provided a stable environment for reproducible HemeChip hemoglobin electrophoresis separation.
Highlights
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland.Paper-based microfluidics provide low-cost, easy-to-use and portable bio-sensing solutions for a broad spectrum of point-of-care (POC) applications, including disease screening/diagnosis, environmental monitoring, food safety, water testing, as well as drug screening and delivery [1,2,3]
We report the methodologies we implemented for characterizing HemeChip system pH and temperature during the development process, including utilizing commercially available universal pH indicator and digital camera pH shift characterization, and infrared camera characterizing temperature shift
The characterization results demonstrated that pH shifts up to 1.1 units, a pH gradient up to 0.11 units/mm, temperature shifts up to 40 ◦ C, and a temperature gradient up to 0.5 ◦ C/mm existed in the system
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Multiple strategies have been developed to mitigate these effects, including employing large-volume liquid reservoirs around the electrodes, involving continuous fluid flow of the buffer solution, as well as adding chemical components to the buffer These strategies are often difficult to employ in miniaturized devices since most of them require large reservoirs or complicated flow systems. These pH and temperature shifts have not been fully characterized in paper-based electrophoresis microfluidic systems such as our HemeChip, some of these technologies are at risk of experiencing compromised separation performance, reproducibility, and robustness under higher electric potentials. We report one approach that we employed to mitigate the pH and temperature shifts in our paper-based microchip electrophoresis system
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