Abstract
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.
Highlights
The development of biosensors devices requires sophisticated approaches to detect and to identify the analytes [1,2,3]
Gold nanoparticles have been widely used during the past few years in various technical and biomedical applications
The resonance optical properties of nanometer-sized particles have been employed to design biochips and biosensors used as analytical tools
Summary
The development of biosensors devices requires sophisticated approaches to detect and to identify the analytes [1,2,3]. The optical properties of gold nanoparticles in the visible and near-infrared (vis-NIR) domains are governed by the collective response of conduction electrons These form an electron gas that moves away from its equilibrium position when perturbed by an external light field, creating induced surface polarization changes that act as a restoring force on the electron gas. This results in a collective oscillatory motion of the electrons similar to the vibrations of a plasma and characterized by a dominant resonance band lying in the vis-NIR for gold and called plasmon excitations. The accurate knowledge of the optical tunability could allow for improving sensing performance, sensitivity, and figure of merit of biosensors operating at detection limit in short time as requested in clinical applications
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