Polyaniline-functionalized ion-sensitive floating-gate FETs for the on-chip monitoring of peroxidase-catalyzed redox reactions

Qi Zhang, Matti Kaisti, Alok Prabhu, Yingjie Yu, Yong Ak Song, Miriam H. Rafailovich, Arifur Rahman, Kalle Levon

Research output: Contribution to journalArticlepeer-review


In this study, we surface-functionalized the extended floating gate (FG) sensing surface (Al2O3) of an ion-sensitive floating-gate field-effect transistor (ISFGFET) with polyaniline/dinonylnaphthalenesulfonic acid (PANI/DNNSA) to construct an organo-surface functionalized bio-sensing device. We measured the threshold voltage (VT) of the device, which was used to determine the potential change at the interface between the PANI/DNNSA layer and aqueous solution. The device was characterized under various pHs as well as enzymatic reaction catalyzed by horseradish peroxidase (HRP) immobilized on the PANI/DNNSA functionalized floating-gate sensing surface. Interestingly, upon surface modifications, the pH and enzymatic reaction sensing behaviors of the device became dependent on the PANI/DNNSA layer, proving that open circuit potentiometric (OCP) responses can be transferred to ISFGFETs. Kinetics of the reactions was tuned through the selection of substrates, exemplified with o-Phenylenediamine (OPD) and 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS). The potential shifts caused by those reactions were explained using an operational model that illustrates “dual sensitivity” of PANI/DNNSA toward ionic and redox species. The sensing concept for the probing of peroxidase-catalyzed charge/electron transfers can potentially be applied to hydrogen peroxide (H2O2) sensing and paves the way for multiplexed potentiometric ELISA tests on such an ion-sensitive field-effect transistor (ISFET) device.

Original languageEnglish (US)
Pages (from-to)256-264
Number of pages9
JournalElectrochimica Acta
StatePublished - Jan 20 2018

ASJC Scopus subject areas

  • General Chemical Engineering
  • Electrochemistry


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