Exhaled Breath analysis of smokers and nonsmokers using sensors based ultrapure Organically Modified Gold Nanoparticles
In this study we present a new technological approach for the fabrication of ultrapure organically modified gold nanoparticles (AuNPs) for chemical sensing applied to exhaled breath analysis. To achieve a high purity level of the sensing films, we combine
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niversidad de Pamplona, Facultad de Ingenierías, EEST, Pamplona, Colombia 2 Universidad de Pamplona, Facultad de Económicas, Pamplona, Colombia 3 MiNoS, Universitat Rovira i Virgili,DEEA, Tarragona, Spain
Abstract— In this study we present a new technological approach for the fabrication of ultrapure organically modified gold nanoparticles (AuNPs) for chemical sensing applied to exhaled breath analysis. To achieve a high purity level of the sensing films, we combined Advanced Gas Deposition (AGD) technique to deposit ultrapure monodispersed AuNPs, and dip coating process for functionalization of the AuNPs with thiolated organic ligands. Morphology and surface analysis revealed the deposition of ultrapure isolated AuNPs after the first processing step, and a network of nanoparticle–ligand nanoassemblies after the second processing step. Gas sensing measurements were performed with exhaled breath samples collected from a group of smokers, a group of non-smokers, and ambient air. Sensors responses towards these samples demonstrated characteristic responses for each study group. PCA analysis further revealed samples classification in three distinct characteristic clusters, which indicates the suitability of the molecularly modified AuNPs presented in this communication for breath analysis applications. Keywords: Monolayer capped AuNPs; advanced Deposition; Breath analysis.
I. INTRODUCTION The search for non-invasive diagnostic methods and diseases monitoring on the basis of volatile organic compounds (VOCs) detected in exhaled breath has led to the development of sensors arrays sensitive to low VOCs concentrations. In this regard, molecularly modified gold nanoparticles have proven excellent potential for detecting very low VOCs concentrations in biofluid samples [1]. The conventional fabrication method of these nanomaterials is based on wet-chemistry processes, which can leave traces of impurities and residual compounds in the sensing film [2]. In order to counteract this negative effect, we propose in this study an innovative methodology that employs the Advanced Gas Deposition technique to fabricate ultrapure, size-controlled, dispersed AuNPs in the first processing step, followed by AuNPs functionalization with thiolated organic ligands in the second processing step. A chemical sensors array based
on monolayer-capped AuNPs fabricated employing this innovative technique was tested for exhaled breath analysis. II.
EXPERIMENTAL
a. AuNPs fabrication and functionalization AuNPs were deposited on sensing devices fabricated on one side polished p-type Si substrates (13 mm x 8 mm) with two parallel Au electrodes, 15 μm gapped, patterned on top by rf-sputtering. Nanoparticles growth and deposition was achieved employing the AGD equipment (ULVAC, Japan) configured in a two-chambers set-up for ultrapure AuNPs generation and deposition [3] – see Fig. 1. A piece of pure gold metal (99.99% purity) was placed on a carbon crucible inside the lower evaporation chamber, and a copper induction coil surrounding the crucible provide
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