UV crosslinked poly(acrylic acid): a simple method to bio-functionalize electrolyte-gated OFET biosensors

Publication year: 2015
Authors: M. Y. Mulla a, P. Seshadri a, L. Torsi a, K. Manoli a, A. Mallardi b, N. Ditaranto a, M. V. Santacroce c, C. Di Franco c, G. Scamarcio c and M. Magliulo, *a

* - Corresponding authors
a - Dipartimento di Chimica, Università degli Studi di Bari “A. Moro”, Via Orabona, 4-70126 Bari, Italy
b - CNR-IPCF, Istituto per i Processi Chimico-Fisici, Via Orabona, 4-70126 Bari, Italy
c - CNR-IFN and Dipartimento Interateneo di Fisica, Università degli Studi di Bari “A. Moro”, Via Orabona, 4 70126, Italy

Published in: Journal of Materials Chemistry B, 2015, Vol. 3, p. 5049-5057
doi: 10.1039/C5TB00243E

A simple and time-saving wet method to endow the surface of organic semiconductor films with carboxyl functional groups is presented. A thin layer of poly(acrylic acid) (pAA) is spin-coated directly on the electronic channel of an electrolyte-gated organic FET (EGOFET) device and cross-linked by UV exposure without the need for any photo-initiator. The carboxyl functionalities are used to anchor phospholipid bilayers through the reaction with the amino-groups of phosphatidyl-ethanolamine (PE). By loading the membranes with phospholipids carrying specific functionalities, such a platform can be easily implemented with recognition elements. Here the case of biotinylated phospholipids that allow selective streptavidin electronic detection is described. The surface morphology and chemical composition are monitored using SEM and XPS, respectively, during the whole process of bio-functionalization. The electronic and sensing performance level of the EGOFET biosensing platform is also evaluated. Selective analyte (streptavidin) detection in the low pM range is achieved, this being orders of magnitude lower than the performance level obtained by the well assessed surface plasmon resonance assay reaching the nM level, at most.

MP-SPR keywords: bioelectronic sensors, crosslinked, electrolyte-gated organic field-effect transistors (EGOFETs), multilayer coating, organic semiconductor (OS), point-of-care, protein binding, SiO2 (silicon dioxide) sensor slide, streptavidin, surface coverage