[Analytical Chemistry] Microfluidic Capillaric Circuit for Rapid and Facile Bacteria Detection
Urinary tract infections (UTI) are one of the most common bacterial infections and would greatly benefit from a rapid point-of-care diagnostic test. Although significant progress has been made in developing microfluidic systems for nucleic acid and whole bacteria immunoassay tests, their practical application is limited by complex protocols, bulky peripherals, and slow operation. Here we present a microfluidic capillaric circuit (CC) optimized for rapid and automated detection of bacteria in urine. Molds for CCs were constructed using previously-established design rules, then 3D-printed and replicated into poly(dimethylsiloxane). CCs autonomously and sequentially performed all liquid delivery steps required for the assay. For efficient bacteria capture, on-the-spot packing of antibody-functionalized microbeads was completed in < 20 s followed by autonomous sequential delivery of 100 uL of bacteria sample, biotinylated detection antibodies, fluorescent streptavidin conjugate, and wash buffer for a total volume ~ 115 uL. The assay was completed in < 7 min. Fluorescence images of the microbead column revealed captured bacteria as bright spots that were easily counted manually or using an automated script for user-independent assay readout. The limit of detection of E. coli in synthetic urine was 1.2 x 10EXP2 colony-forming-units per mL (CFU/mL), which is well below the clinical diagnostic criterion (> 10EXP5 CFU/mL) for UTI. The self-powered, peripheral-free CC presented here has potential for use in rapid point-of-care UTI screening.
Ayokunle Oluwafemi Olanrewaju, Andy Ng, Philippe Decorwin-Martin, Alessandra Robillard, and David Juncker Anal. Chem., Just Accepted Manuscript DOI: 10.1021/acs.analchem.7b01315 Publication Date (Web): May 25, 2017 Copyright © 2017 American Chemical Society