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Advances in Optical Technologies
Volume 2012 (2012), Article ID 278194, 8 pages
Research Article

Nanoscale Biomolecular Detection Limit for Gold Nanoparticles Based on Near-Infrared Response

1Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via Fosso del Cavaliere 100, 00133 Roma, Italy
2Istituto di Scienze e Tecnologia dell’Informazione, Consiglio Nazionale delle Ricerche, Via Moruzzi 1, 56124 Pisa, Italy

Received 27 July 2012; Accepted 31 October 2012

Academic Editor: Carlo Corsi

Copyright © 2012 Mario D’Acunto et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Gold nanoparticles have been widely used during the past few years in various technical and biomedical applications. In particular, the resonance optical properties of nanometer-sized particles have been employed to design biochips and biosensors used as analytical tools. The optical properties of nonfunctionalized gold nanoparticles and core-gold nanoshells play a crucial role for the design of biosensors where gold surface is used as a sensing component. Gold nanoparticles exhibit excellent optical tunability at visible and near-infrared frequencies leading to sharp peaks in their spectral extinction. In this paper, we study how the optical properties of gold nanoparticles and core-gold nanoshells are changed as a function of different sizes, shapes, composition, and biomolecular coating with characteristic shifts towards the near-infrared region. We show that the optical tenability can be carefully tailored for particle sizes falling in the range 100–150 nm. The results should improve the design of sensors working at the detection limit.