Ionic Liquid Aqueous Two-Phase Systems for the Enhanced Paper-Based Detection of Transferrin and Escherichia coli.

Matthew F Yee,Daniel T Kamei,Benjamin M Wu,Grace N Emmel,Eumene Lee,Eric J Yang,Justin H Paek

doi:10.3389/fchem.2018.00486

Abstract

Aqueous two-phase systems (ATPSs) have been widely utilized for liquid-liquid extraction and purification of biomolecules, with some studies also demonstrating their capacity as a biomarker concentration technique for use in diagnostic settings. As the limited polarity range of conventional polymer-based ATPSs can restrict their use, ionic liquid (IL)-based ATPSs have been recently proposed as a promising alternative to polymer-based ATPSs, since ILs are regarded as tunable solvents with excellent solvation capabilities for a variety of natural compounds and proteins. This study demonstrates the first application of IL ATPSs to point-of-care diagnostics. ATPSs consisting of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) and sodium phosphate salt were utilized to quickly concentrate biomarkers prior to detection using the lateral-flow immunoassay (LFA). We found the phase separation speed of the IL ATPS to be very rapid and a significant improvement upon the separation speed of both polymer-salt and micellar ATPSs. This system was successfully applied to both sandwich and competitive LFA formats and enhanced the detection of both Escherichia coli bacteria and the transferrin protein up to 8- and 20-fold, respectively. This system's compatibility with a broad range of biomolecules, rapid phase separation speed, and tunability suggest wide applicability for a large range of different antigens and biomarkers.

Highlights

While global health has improved over the last few decades, health pandemics in resource-poor settings remain a large problem (Scarborough and Thwaites, 2008; Tang and Nour, 2010; Gunasekera and Pathiraja, 2016)
Following the detection of Tf, we studied the detection of E. coli as a large biomarker to demonstrate improvement using an ionic liquid (IL) Aqueous two-phase systems (ATPSs) in a sandwich-format lateral-flow immunoassay (LFA), where diminishing of line intensities will have a negative impact on the detection limit
We successfully demonstrated the first use of an IL ATPS for the enhanced detection of biomarkers with the LFA

Summary

Introduction

While global health has improved over the last few decades, health pandemics in resource-poor settings remain a large problem (Scarborough and Thwaites, 2008; Tang and Nour, 2010; Gunasekera and Pathiraja, 2016). In countries like the U.S, many of these illnesses are readily treatable, especially when diagnosed early; in resource-poor settings, patients lack easy access to standard laboratory-based tests such as the enzyme-linked immunosorbent assay (ELISA), nucleic acid amplification tests, and serology tests (Elbireer et al, 2011) With issues such as poor infrastructure and limited funding already leading to underutilization of central laboratories in these resource-poor settings (Elbireer et al, 2011; Nkengasong et al, 2018), there is a growing interest in Biomolecule Detection With Ionic Liquids developing point-of-care techniques to diagnose a variety of diseases. In comparison to the gold standard laboratory-based tests, these devices are still restricted by their limited sensitivity, indicating an increasing need for enhanced detection capabilities at the point-of-care

Methods

Results

Discussion

Conclusion