Nanoparticle-Supported, Rapid Detection of Shiga Toxin-Producing E. coli Infection from Food Matrices and Human Specimens

Authors:
Preprint
Publisher website
Google Scholar
Abstract
Shiga toxin-producing Escherichia coli (STEC) are major foodborne pathogens responsible for severe infections, sometimes fatal. However, the current diagnostic methods lack the sensitivity and speed required for effective clinical assessment and food safety inspection. Highly sensitive detection of Shiga toxin 2 (Stx2), a primary virulence factor of STEC, could potentially offer critical benefits for timely intervention. In this work, gold nanoparticles (AuNPs) are functionalized with a pair of high-affinity designed ankyrin repeat proteins (DARPins), targeting the A and B subunits of Stx2, and used as multifunctional signal transducers for rapid electronic detection (RED) of Stx2. This DARPin-RED platform leverages active centrifugal forces, vortex agitation, and a digital readout device for rapid (<30 min), yet highly sensitive (fg/mL-level) detection of Stx2 in food matrices (e.g. milk, lettuce extract, and ground beef extract) and biological fluids. For example, the analytical limits of detection (LoDs) are 14.8, 38, and 25 fg/mL in serum, whole blood, and stool, respectively, supporting future evaluation in well-characterized clinical specimens. Additionally, DARPin-RED can detect multiple Stx2 subtypes with minimal background interference, distinguish different bacterial inoculation doses (p = 0.011), resolve incubation-time-dependent toxin production, and differentiate high-toxin-producing E. coli strains (e.g. RM5856) from low-toxin producers (e.g. RM9872) (p = 0.037). These results establish DARPin-RED as a rapid and sensitive analytical platform for further development in STEC testing and food-safety surveillance.

This publication has 32 references indexed in Scilit: