Biosensors and Bioelectronics 20 (2004) 1203–1210 Piezoelectric sensors for dioxins: a biomimetic approach M. Mascini a,e,∗ , A. Macagnano b , D. Monti c , M. Del Carlo a , R. Paolesse b,c , B. Chen d,e , P. Warner e , A. D’Amico b,f , C. Di Natale b,f , D. Compagnone a a Dipartimento di Scienze degli Alimenti, Universit` a di Teramo, 64023 Teramo, Italy b IMM-CNR Sezione di Roma, 00133 Roma, Italy c Dipartimento di Scienze e Tecnologie Chimiche, Universit` a “Tor Vergata”, 00133 Roma, Italy d Department of Chemistry, Sheffield University, Sheffield S10 2TN, UK e Institute of BioScience and Technology, Cranfield University at Silsoe, Bedfordshire MK43 0AL, UK f Dipartimento di Ingegneria Elettronica, Universit` a “Tor Vergata”, 00133 Roma, Italy Received 12 November 2003; received in revised form 10 June 2004; accepted 16 June 2004 Available online 20 August 2004 Abstract The aim of this work was to design a fast, cheap and easy to use analytical system for dioxins. Piezoelectric sensors coupled with the pentapeptides as biomimetic traps (the receptors), selective for the dioxins, were used for the realisation of this analytical system. A methodology to select specific receptors among all possible pentapeptides randomly generated was represented by the use of molecular modelling software. Three peptides called later on A, B and C (A:[N]Asn-Phe-Gln-Gly-Ile[C]; B:[N]Asn-Phe-Gln-Gly-Gln[C]; C:[N]Asn- Phe-Gln-Gly-Phe[C]), were selected and evaluated for their potential usage as artificial receptors in solid–gas analysis by using a quartz crystal microbalance (QCM) sensors array. The peptide sequences were functionalised by two terminal cysteine residues in order to achieve a covalent interaction with the QCM gold surface. A manganese–porphyrin complex and two other pentapeptides, a pentaglutamine (pentapeptide D) and a pentalysine (pentapeptide E), were used as negative control sensors. The QCM sensors (A, B and C) gave a good linearity against different sample concentrations of the 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) and a mixture of dioxins. In particular, the selectivity against 2,3,7,8-TCDD was nicely correlated to the estimated binding energy of the receptors calculcated by computational modelling. The cross-reactivity of the system was quantified using commercial polychlorinated biphenyls (PCBs) mixtures (dioxin-like compounds). © 2004 Elsevier B.V. All rights reserved. Keywords: Molecular modelling; Pentapeptides; Piezoelectric gas sensors; Dioxins 1. Introduction Dioxins and dioxin-like compounds are collective terms for the group of polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs), which belong to the chlo- rinated hydrocarbons (CHCs). The Dioxins family has as many as 200 compounds. They are highly toxic substances, and well-known environmental pollutants and carcinogens (World Health Organization, 1999). The US Environmental Protection Agency method (EPA, 1994), assigned for dioxin detection, requires the use of high- ∗ Corresponding author. Tel.: +39 085 8071509; fax: +39 085 8071509. E-mail address: mmascini@unite.it (M. Mascini). resolution gas chromatography(HRGS) and high-resolution mass spectrometry (HRMS) on sample extracts that have been subjected to three specified cleanup steps (acid/base treatment; silica gel and alumina column chromatography; carbon column chromatography). The toxicity of an individ- ual dioxin compound is expressed as toxicity equivalence (TEQ) with respect to 2,3,7,8-tetrachlorinated dibenzo-p- dioxin (TCDD) (World Health Organization, 1997). These techniques are known for high sensitivity but rather expen- sive, slow and difficult procedures needs to be carried out. It is of fundamental importance to build selective sensors for this class of compounds. Piezoelectric sensors using the peptides as biomimetic traps, selective to the dioxins, can be used as new analytical 0956-5663/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.bios.2004.06.048