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    Direct, Label-Free, and Rapid Transistor-Based Immunodetection in Whole Serum

    Year: 2017

    Journal: ACS Sens., Volume 2, SEP, page 1278–1286

    Authors: Gutierrez-Sanz, Oscar; Andoy, Nesha M.; Filipiak, Marcin S.; Haustein, Natalie; Tarasov, Alexey

    Keywords: Debye length; field-effect transistor (FET); biosensor; thyroid-stimulating hormone (TSH); label-free; serum

    Transistor-based biosensors fulfill many requirements posed upon transducers for future point-of-care diagnostic devices such as scalable fabrication and label-free and real-time quantification of chemical and biological species with high sensitivity. However, the short Debye screening length in physiological samples (<1 nm) has been a major drawback so far, preventing direct measurements in serum. In this work, we demonstrate how tailoring the sensing surface with short specific biological receptors and a polymer polyethylene glycol (PEG) can strongly enhance the sensor response. In addition, the sensor performance can be dramatically improved if the measurements are performed at elevated temperatures (37 degrees C instead of 21 degrees C). With this novel approach, highly sensitive and selective detection of a representative immunosensing parameter human thyroid-stimulating hormone is shown over a wide measuring range with subpicomolar detection limits in whole serum. To the best of our knowledge, this is the first demonstration of direct immunodetection in whole serum using transistor-based biosensors, without the need for sample pretreatment, labeling, or washing steps. The presented sensor is low-cost, can be easily integrated into portable diagnostics devices, and offers a competitive performance compared to state-of-the-art central laboratory analyzers.
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