Biosensors & Bioelectronics

Electrochemical Impedance Spectroscopy (EIS) as a Tool for Pathogen Detection

Abstract

Ducote M, Vinson BT, Hogquist S, Riggs B, Saksena J and Chrisey DB*

Background: In the event of a biological warfare attack, prompt real-time detection methods are necessary to identify the presence of a pathogen well before victims begin exhibiting symptoms in order to allow sufficient time for therapeutic intervention. Current techniques for detecting the presence of biological warfare agents in high-risk environments are exclusively structure-based, relying on the identification of key structural components of specific pathogens that are already well-known and studied. These techniques provide no defense against the modern capability to synthesize new and unfamiliar pathogens of an arbitrary structure that could evade these detection mechanisms.

Methods/Results: This investigation tested the prospect of using electrochemical impedance spectroscopy (EIS) to create a real-time function-based biosensor to identify any cytotoxic substance, whether known or unknown, without regard to its structure. The concept was tested by exposing A549 epithelial adenocarcinoma cells to ricin in several concentrations, ranging from 1 ng/mL to 1000 ng/mL, and observing the effect on the measured impedance of the cells. With as few as three unique trials for each concentration, a statistically significant difference was observed between the impedance data for ricin-exposed cells and that of a ricin-free control group. By comparing the change in the impedance of each sample over periods of 60 minutes and 4 hours, statistically significant detection was achieved within timeframes ranging from 65 minutes after adding 1000 ng/mL ricin to 45 hours after adding 1 ng/mL ricin.

Conclusion: EIS provides a highly sensitive, real-time, and non-destructive method to identify the presence of a cytotoxin. EIS demonstrates rapid detection times that become faster as the concentration increases. Further analysis describes how the design of a potential biosensing device could be used to convert an arbitrary airborne concentration to a media concentration sufficiently large as to achieve detection within the window of time necessary for therapeutic intervention.