Gold nanoparticles-peptide based gas sensor arrays for the detection of food aromas D. Compagnone a,n , G.C. Fusella a , M. Del Carlo a , P. Pittia a , E. Martinelli b , L. Tortora c , R. Paolesse c , C. Di Natale b a Department of Food Sciences, University of Teramo, via C. Lerici 1, Mosciano S.A. 64023, Italy b Department of Electronic Engineering, University of Tor Vergata, via del Politecnico 1, 00133, Rome, Italy c Department of Chemical Sciences and Technologies, University of Tor Vergata, via della Ricerca Scientifica 1, 00133 Rome, Italy article info Article history: Received 12 June 2012 Received in revised form 25 October 2012 Accepted 30 October 2012 Available online 22 November 2012 Keywords: Gas sensor array Peptides Gold nanoparticles QCMs Food aromas abstract A gas sensor array based on peptide modified gold nanoparticles deposited onto 20 MHz quartz crystal microbalances has been realized. Glutathione and its constituting aminoacids and dipeptides have been used as ligands. A great increase in sensitivity (2 orders of magnitude) was achieved using gold nanoparticles versus monolayer modified QCMs. The sensors have been charachterised in terms of sensitivity for hexane, water, trimethylammine and ethanol. Highest sensitivity was found for water. The ability to discriminate typical food aromas as cis-3-hexenol, isopentylacetate, ethylacetate, and terpinen-4-ol dissolved in different solvents was studied using a gas sensor array constituted by gold nanoparticles modified with the glutathione peptides, thioglycolic acid and an heptapeptide. The array was found able to discriminate the food aromas, the response being dependent on the polarity of the solvent used. Tests on real olive oil samples gave a satisfactory separation among samples having defects versus non defected samples demonstrating that this approach has high potential for the development of gas sensor arrays to be used in real samples. & 2012 Elsevier B.V. All rights reserved. 1. Introduction The use of oligopeptides as binding elements in affinity sensing has represented in recent years a challenge for the development of the so called biomimetic biosensors. Because of the binding ability of mimicking protein receptors and antibodies, ease of synthetic routes and high number of potential structural arrangements, they have been reported as valuable alternative to other biomimetic sensing approaches based, for example, on molecularly imprinted polymers and aptamers. Quartz crystal microbalance (QCM) based sensing appear very useful for the development of oligopeptide based sensors. In fact, in addition to the low cost and ease of handling of the devices, the presence of the gold electrodes on the QCM results particu- larly useful to immobilize the peptides via self-assembled mono- layer, using cysteine as terminal aminoacid or a thiolated spacer. With this approach classical piezoelectric biosensors operating in liquid phase have been developed; these were mainly designed for the detection of proteins having high affinity for the immo- bilized peptides. Melles et al. (2005) have proposed the immobi- lization of proinsulin C-peptide for protein purification purposes, Mascini et al. (2006) developed heptapeptides based biosensors for the detection of heat shock proteins 70 in mussels using a computational/combinatorial approach, Okada et al. (2007) immobilized peptides onto QCMs to evaluate their affinity to profilin while Luo et al. (2007) proposed a similar approach for the detection of recombinant human interferon b. An inter- esting work, in which peptides have been immobilized of carbon nanotubes deposited on QCMs has been also reported by Drouvalakis et al. (2008); this sensor was directed to the detec- tion of disease-specific autoantibodies. The use of aminoacids or oligopeptides in gas phase has been also attempted. Efforts have been directed by Wu (1999) in the immobilization of purified olphactory receptor proteins and later by Wu et al. (2001) and by Lu et al. (2009) in the immobilization of peptides for the detection of volatile organic carbons (VOCs). Different peptides, obtained using molecular modeling and dock- ing experiments on the binding sites of odorant binding proteins, were tested to achieve selectivity versus different volatile organic compounds using a specially designed cell. An e-nose for the diagnosis of uremia based on adsorbed peptides modeled on trans-membrane receptor proteins has been also proposed by Lin et al. (2001). A similar approach was used by Sankaran et al. (2011a, 2011b) in 2 papers to obtain gas sensing of alcohols (3-methyl-1-butanol and 1-hexanol) associated with the presence Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/bios Biosensors and Bioelectronics 0956-5663/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.bios.2012.10.096 n Corresponding author. E-mail address: dcompagnone@unite.it (D. Compagnone). Biosensors and Bioelectronics 42 (2013) 618–625