Development of ion-sensitive field-effect transistor-based sensors for benzylphosphonic acids and th.pdf

Analytica Chimica Acta 504 (2004) 113–122 Development of ion-sensitive field-effect transistor-based sensors for benzylphosphonic acids and thiophenols using molecularly imprinted TiO2 films Svetlana P. Pogorelova a,? , Andrei B. Kharitonov a , Itamar Willner a , Chaim N. Sukenik b , Hillel Pizem b , Thomas Bayer b a Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel b Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel Received 6 January 2003; received in revised form 17 April 2003; accepted 28 April 2003 Abstract Molecularly imprinted polymeric membranes, containing artificial recognition sites for a number of benzylphosphonic acid derivatives, were prepared by the polymerization of titanium(IV) butoxide in the presence of a titanium(IV) phosphonate complex. Reference polymers were prepared in the same manner but in the absence of the phosphonate template. FTIR spectroscopy was used to follow the formation of a benzylphosphonic acid–Titanium(IV) oxide complex during the imprinting process, and upon the association of the substrate in the imprinted TiO2 thin film. The imprinted polymers were examined as sensing membranes in an ion-sensitive field-effect transistors (ISFETs). The sensors reveal selectivity towards analyzing the imprinted substrates, yet the recognition ability of the sensors strongly depends on the substituents associated with the phosphonic acid structures. The response time of the sensors is ca. 45 s, and the sensors reveal unaffected stability for at least 2 weeks. Also, imprinted TiO2 films for thiophenol, and para-nitrothiophenol were generated on ISFET devices, and the respective substrates were selectively sensed by the functional devices. ? 2003 Elsevier B.V. All rights reserved. Keywords: Imprinted polymers; ISFET; Sensors; Benzylphosphonic acids; Thiophenol; Sol-gel 1. Introduction Substantial research activities are directed to the devel- opment of specific simple, cheap and miniaturized