(241c) Printed Electronic Biosensors for Protein Detection

Floating gate transistor (FGT) sensors offer the potential for label-free detection of biomolecules with high sensitivity. In the typical ChemFET sensing strategy, the transistor is immersed in the sample solution. Binding of an analyte to the gate electrode or the semiconductor turns the transistor ON and produces the signal. This approach imposes substantial constraints on the materials used for the transistor, since one needs to balance the electronic properties of the semiconductor with its stability in the (aqueous) sensing environment.

To solve this problem with ChemFETs, we have developed a side-gated FGT sensing strategy that decouples the electronics from the sensing environment. In our approach, the semiconductor channel is capacitively coupled to a floating gate, the latter being functionalized with an antibody or aptamer for the desired analyte, and only the floating gate is available for binding. The potential of the floating gate is controlled by the main gate electrode, which is also in contact with an electrolyte solution. Binding of the target molecule to the antibody or aptamer film on the floating gate can turn the transistor ON. To enhance sensitivity and speed of analysis, we have augmented this basic architecture with an ion-gel dielectric, which provides large charge separation at relatively modest applied potentials and allows us to fabricate the electronics using aerosol jet printing, and a microfluidic system that permits rapid mass transfer to the sensor surface and prevents contact between the main gate and the sample solution.

In the first part of this presentation, I will present a series of fundamental experiments that we have used to uncover the details of the sensing mechanism and design rules to enhance sensitivity. In the second part, I will present results for the detection of increasingly challenging analytes, moving from DNA hybridization to ricin to gluten, in challenging matrices such as liquid foods and strongly reducing media. In particular, these applications demonstrate the ability of this sensing strategy to achieve quantitative detection and limits-of-detection at application relevant levels (e.g., “gluten free”) without the need for any pre-concentration steps or sample cleanup.

References:

Scott P. White, Srinand Sreevatsan, C. Daniel Frisbie and Kevin D. Dorfman, Rapid, selective, label-free aptameric capture and detection of ricin using a printed floating gate transistor. ACS Sensors 1, 1213-1216 (2016).

Scott P. White, Kevin D. Dorfman and C. Daniel Frisbie, Operating and sensing mechanism of electrolyte-gated transistors with floating gates: Building a platform for amplified biodetection. Journal of Physical Chemistry C 120, 108-117 (2016).

Scott P. White, Kevin D. Dorfman and C. Daniel Frisbie, Label-free DNA sensing platform with low-voltage electrolyte-gated transistors. Analytical Chemistry 87, 1861-1866 (2015).