Seed induced growth of binary Ag/Au nanostructures on a graphite surface

The growth of Ag on a graphite surface decorated by size selected Au "seed" nanoclusters is investigated. Compared with the behavior on bare graphite, the deposition of the Au clusters decreases the lateral diffusion of Ag atoms and enables the growth of Ag/Au nanostructures on/around the top of the initial Au clusters. Depending on the Au cluster shape, which can be tuned by the cluster deposition energy, Ag deposition either leads to 2 ML high platelets or three-dimensional nanoclusters. This cluster seeding technique shows potential for the rapid production of binary model catalysts, biochips, and optical films

Functionalization layer influence on the sensitivity of surface plasmon resonance (SPR) biosensor

1 - ArticlePlasmonic biosensors represent a rapidly expanding interdisciplinary field with numerous transducers which are based principally on the optical measurement of the plasmon shift, that is induced by the change of surrounding water optical index, due to the presence of biomaterials, in a binding event. A functionalization layer is practically used for selective detection of the molecules of interest. In this paper we show how this material can modify the sensitivity of the biosensor and we propose an optimization of the biosensor

Highly sensitive detection of estradiol by a SERS sensor based on TiO2 covered with gold nanoparticles

We propose the use of gold nanoparticles grown on the surface of nanoporous TiO2 films as Surface Enhanced Raman Scattering (SERS) sensors for the detection of 17-estradiol. Gold deposition on top of TiO2 surfaces leads to the formation of nanoparticles, which plasmonic properties fit the requirements of a SERS sensor well. The morphological and optical properties of this surface were investigated. Specifically, we demonstrated that the TiO2 background pressure during pulsed laser deposition and annealing conditions enabled the formation of a variety of Au nanoparticles with controlled size, shape and distribution thus resulting in a versatile sensor. We have exploited this surface for the detection of 17-estradiol, an emerging contaminant in environmental waters. We have found a limit of detection of 1 nM with a sensitivity allowing dynamic range of five orders of magnitude (up to 100 µM)

Nanoplasmonics tuned “click chemistry”

Nanoplasmonics is a growing field of optical condensed matter science dedicated to optical phenomena at the nanoscale level in metal systems. Extensive research on noble metallic nanoparticles (NPs) has emerged within the last two decades due to their ability to keep the optical energy concentrated in the vicinity of NPs, in particular, the ability to create optical near-field enhancement followed by heat generation. We have exploited these properties in order to induce a localised “click” reaction in the vicinity of gold nanostructures under unfavourable experimental conditions. We demonstrate that this reaction can be controlled by the plasmonic properties of the nanostructures and we propose two physical mechanisms to interpret the observed plasmonic tuning of the “click” chemistry

Sensing Polymer/Paracetamol Interaction with an Independent Component Analysis-Based SERS-MIP Nanosensor

In this article, we propose a new strategy to build a sensor for easy handling and rapid analysis on-site. Our sensor is based on the combination of surface-enhanced Raman spectroscopy (SERS) and molecularly imprinted polymers (MIPs). SERS provides a strong sensitivity for the detection of trace molecules while MIPs offer a highly selective and specific recognition platform. The research presented here focuses on the detection of the interaction between a robust ultra-thin layer of MIPs and of paracetamol, the targeted molecule. This drug is an environmental emerging pollutant, i.e., a molecule whose presence and significance have not yet been elucidated, which gives rise to health and environmental concerns. The results are a combined analysis of the SERS spectra and a multivariate analysis. The former provides a clear demonstration of the evolution of the MIP-nanostructure interaction when the concentration of paracetamol increases. The statistical analysis produces the proof of the selectivity of the senso

Multi-functionalization of lithographically designed gold nanodisks by plasmon-mediated reduction of aryl diazonium salts

International audiencePlasmon-driven surface functionalization of nanoparticles is receiving growing attention as it allows generating locally tailored chemical reactivity on the nanoparticle surface. The extension to surface multi-functionalization still represents a major breakthrough in chemistry. We address this issue by triggering regiospecific surface double-functionalization under plasmon excitation, using diazonium salts as surface functionalization agents