Real-time, Specific and Sensitive Detection of Salmonella Using a Hand-held Immuno Field Effect Transistor (ImmunoFET)

Introduction: Today, most foodborne pathogen testing requires dedicated, off-site labs, specialized equipment, trained personnel and can often takes days to complete. With the goal of shifting the paradigm to on-site, real-time results, we have developed a high sensitivity, incubation-free detection system for pathogen contaminants, in a portable, user-friendly format. Our platform technology utilizes a solid-state field effect transistor functionalized with an antibody (an immunoFET) to detect specific analytes of interest in small volume liquid samples, with a turnaround time of minutes.

Purpose: The purpose of this study is to demonstrate the sensitivity and specificity of an immunoFET sensor for the detection of Salmonella enterica bacteria.

Methods: ImmunoFETs functionalized with an anti-Salmonella antibody were used to detect the presence of S. enterica at different concentrations in blinded, artificially contaminated saline solutions. Cross-reactivity of the immunoFET to other bacteria was evaluated using spiked solutions of Escherichia coli and Listeria monocytogenes.

Results: Preliminary data shows that the lowest concentration of S. enterica detectable with our immunoFET sensor is 100 colony forming units/ml. Further, the immunoFET accurately identified the presence or absence of S. enterica in spiked samples in our trials. We did not detect cross-reactivity of our sensor with samples spiked with E. coli or L. monocytogenes. Total time from sampling to result output is less than 10 min.

Significance: We have demonstrated that our immunoFET sensor can directly measure the presence of even low concentrations of S. enterica in liquid samples within minutes, eliminating the need for sample incubation. Our handheld sensor can be readily used with little training, at the point of testing, to accurately identify and quantify contamination.