Investigating bottom phase extraction from aqueous two-phase systems for detecting bacteria using the lateral-flow...

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Clinical Diagnostics

Background:

• Urinary tract infections (UTIs) are commonly diagnosed using lateral-flow immunoassays (LFAs).
• Dilute bacterial concentrations in urine samples can lead to false-negative results with current LFAs.
• Point-of-care diagnostics require methods robust to sample variability.

Purpose of the Study:

• To implement aqueous two-phase systems (ATPSs) for preconcentrating Escherichia coli (E. coli) in urine samples before LFA analysis.
• To demonstrate that ATPS preconcentration improves LFA sensitivity for E. coli detection.
• To develop a streamlined workflow for point-of-care UTI diagnostics.

Main Methods:

• Utilized ATPS to partition and preconcentrate E. coli biomarkers into a smaller volume (bottom phase).
• Investigated the effect of volume ratio (VR) on preconcentration efficiency and LFA sensitivity.
• Developed a custom 3D-printed device to minimize manual liquid handling steps.
• Validated the workflow using synthetic urine samples with varying E. coli concentrations.

Main Results:

• Achieved consistent limit of detection (LOD) irrespective of the VR when the entire bottom phase was applied to LFAs.
• Demonstrated a 10-fold improvement in sensitivity compared to non-preconcentrated samples.
• Successfully detected E. coli down to 2 × 10^5 colony-forming units (cfu) mL^-1 in synthetic urine.
• The 3D-printed device reduced liquid handling, enhancing ease of use.

Conclusions:

• ATPS preconcentration is an effective strategy to overcome sensitivity limitations of LFAs for E. coli detection.
• The developed workflow addresses patient sample variability, improving diagnostic accuracy at the point of care.
• This integrated approach offers a robust and user-friendly solution for UTI diagnostics.