Electrochemical biosensors continue to develop as purposeful tools for food safety and environmental monitoring. Within this class, electrolyte-gated transistors are an attractive, emerging platform due to their use of high-capacitance and solution-processable materials. This combination yields low voltage operation, ease of fabrication, and the ability to amplify molecular binding events into quantifiable, electronic signals. Of the various existing platforms, the floating gate transistor (FGT) is unique in that it utilizes a coplanar floating gate to electronically couple the electrolyte-gated transistor to the aqueous sensing medium while physically separating the two compartments. Advantages of the FGT include prevention of incompatibility between the biological environment and transistor materials, versatile surface chemistries on gold for sensing surface design, and independent, strategic engineering of the two compartments for signal enhancement.<br/><br/>To date, FGTs have demonstrated detection capabilities of large, charged molecules, including proteins and DNA. With advanced understanding in the underlying mechanisms that dictate FGT responses to charge- and capacitance-based signals, the architecture and materials can now be designed for optimal sensitivity to alternative analytes of interest, in particular small molecules. The herbicide, glyphosate, is chosen based on its widespread use in agricultural applications, environmental and public health threats, and lack of alternatives to complex analytical instrumentation for detection. Surface chemistry for anti-glyphosate antibody conjugation to gold has been optimized and characterized with x-ray photoelectron spectroscopy, infrared spectroscopy, and epifluorescence microscopy. Our findings show specific detection of glyphosate with FGTs down to the lower limit of EPA tolerances (0.1 – 400 ppm), with minimal responses in antibody-free FGTs. A relatively simple equipment set and rapid sensing advance the platform toward user-friendly and on-site environmental monitoring of small molecule toxins.

Detection of the small molecule herbicide, glyphosate, with a floating gate transistor

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.