Selective and Collaborative Optimization Methods for Plasmonics: A Comparison

International audienceIn this paper, we optimize the size parameters of hollow nanospheres and nanoshells used in cancer photothermal therapy and we focus on two practical therapy cases: the visible range for shallow cancer and the near infrared for deep cancer. For this, we consider analytical models: the Mie theory for coated spheres. The investigated optimization methods are the Evolutionary Method (EM) and the Particle Swarm Optimization (PSO) which are based on competitiveness and collaborative algorithms, respectively. A comparative study is achieved by checking the efficiency of the optimization methods, to improve the nanoparticles efficiency

Electromagnetic Heat-induced in Meso-structures: Computation of Temperature in Metallic Dimers

International audienceThe illumination of a dimer metallic nanostructure is known to produce an in- tense source of light, with nanometric size. This con¯nement of light in the gap between the two material structures can induce an increase of the absorption of the electromagnetic energy in the nanaoantenna itself, and therefore its warm-up. The multiphysics problem associated to this photo-thermal e®ect is modeled through a Finite Element Method (FEM). This contribu- tion consists in computing both the electromagnetic ¯eld and the temperature, and discussing the in°uence of the gap, in the case of a bow-tie nanoantenna. The applications could be the development of nanodevices with thermal properties

SERS detection of biomolecules using lithographied nanoparticles towards a reproducible SERS biosensor

International audienceIn this paper we highlight the accurate spectral detection of bovine serum albumin and ribonuclease-A using a Surface-Enhanced Raman Scattering (SERS) substrate based on gold nanocylinders obtained by Electron-Beam Lithography (EBL). The nanocylinders have diameter from 100 to 180 nm with a gap of 200 nm. We demonstrate that optimizing the size and the shape of the lithographied gold nanocylinders, we can obtain SERS spectra of proteins at low concentration. This SERS study enabled us to estimate high enhancement factors (105 for BSA and 107 for RNase-A) of important bands in the protein Raman spectrum measured for 1mM concentration. We demonstrate that to reach the highest enhancement it is necessary to optimize the SERS signal and that the main parameter of optimization is the LSPR position. The LSPR have to be suitably located between the laser excitation wavelength which is 632.8 nm and the position of the considered Raman band. Our study underlines the efficiency of gold nanocylinders arrays in spectral detection of proteins

Nanoshells for photothermal therapy: a Monte-Carlo based numerical study of their design tolerance

The optimization of the coated metallic nanoparticles and nanoshells is a current challenge for biological applications, especially for cancer photothermal therapy, considering both the continuous improvement of their fabrication and the increasing requirement of efficiency. The efficiency of the coupling between illumination with such nanostructures for burning purposes depends unevenly on their geometrical parameters (radius, thickness of the shell) and material parameters (permittivities which depend on the illumination wavelength). Through a Monte-Carlo method, we propose a numerical study of such nanodevice, to evaluate tolerances (or uncertainty) on these parameters, given a threshold of efficiency, to facilitate the design of nanoparticles. The results could help to focus on the relevant parameters of the engineering process for which the absorbed energy is the most dependant. The Monte-Carlo method confirms that the best burning efficiency are obtained for hollow nanospheres and exhibit the sensitivity of the absorbed electromagnetic energy as a function of each parameter. The proposed method is general and could be applied in design and development of new embedded coated nanomaterials used in biomedicine applications

Electromagnetic Heat-induced in Meso-structures: Computation of Temperature in Metallic Dimers

International audienceThe illumination of a dimer metallic nanostructure is known to produce an in- tense source of light, with nanometric size. This con¯nement of light in the gap between the two material structures can induce an increase of the absorption of the electromagnetic energy in the nanaoantenna itself, and therefore its warm-up. The multiphysics problem associated to this photo-thermal e®ect is modeled through a Finite Element Method (FEM). This contribu- tion consists in computing both the electromagnetic ¯eld and the temperature, and discussing the in°uence of the gap, in the case of a bow-tie nanoantenna. The applications could be the development of nanodevices with thermal properties

Pegylated doxorubicin gold complex: From nanovector to potential intercalant agent for biosensor applications

We report an original approach to synthesize hybrid gold nanostructures in which doxorubicin (DOX), mixed to Poliethylenglycole diacid (PEG-COOH) led to original hybrid gold nanovector (DOX IN PEG AuNPs). In this work, we investigate the ability of DOX IN PEG-AuNPs to detect the amplification of the hybridization process by a sensitive Quartz crystal Microbalance with dissipation (QCM-D) by intercalation process. The sensing layer was carried out by self-assembled monolayer of β mercaptoethylamine (cysteamine) on gold-coated quartz crystal sensor composed by a rigid homobifunctional cross-linker 1,4 phenilenediisothiocyanate (PDITC) linked covalently with amino-probe oligonucleotides. By QCM characterization in the range from 8 µM to 20 nM, we demonstrate high specificity of DOX IN PEG-AuNPs-DNA with a limit of detection (LOD) of 9 nM. This result is very promising for development of sensitive and effective nanoparticle-based biosensor for quantifying small biomolecules concentration in physiological liquids. These results open a possibility to realize a new class of nanovector which will be tailored for different biomedical application, such as imaging, targeting and drugs delivery. Keywords: Quartz Crystal Microbalance (QCM), Chemical surface, DNA hybridization, Gold nanoparticles, Doxorubici

Defect-induced activation of symmetry forbidden infrared resonances in individual metallic nanorods

International audienceWe report on the observation of second-order infrared (IR) plasmon resonances in lithographically prepared gold nanorods investigated by means of far-field microscopic IR spectroscopy. In addition to the fundamental antennalike mode, even and odd higher order resonances are observed under normal incidence of light. The activation of even-order modes under normal incidence is surprising since even orders are dipole-forbidden because of their centrosymmetric charge density oscillation. Performing atomic force microscopy and calculations with the boundary element method, we determine that excitation of even modes is enabled by symmetry breaking by structural deviations of the rods from an ideal, straight shape. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3437093

Towards Reliable and Quantitative Surface‐Enhanced Raman Scattering (SERS): From Key Parameters to Good Analytical Practice

Experimental results obtained in different laboratories world‐wide by researchers using surface‐enhanced Raman scattering (SERS) can differ significantly. We, an international team of scientists with long‐standing expertise in SERS, address this issue from our perspective by presenting considerations on reliable and quantitative SERS. The central idea of this joint effort is to highlight key parameters and pitfalls that are often encountered in the literature. To that end, we provide here a series of recommendations on: a) the characterization of solid and colloidal SERS substrates by correlative electron and optical microscopy and spectroscopy, b) on the determination of the SERS enhancement factor (EF), including suitable Raman reporter/probe molecules, and finally on c) good analytical practice. We hope that both newcomers and specialists will benefit from these recommendations to increase the inter‐laboratory comparability of experimental SERS results and further establish SERS as an analytical tool.Peer Reviewe

Endemic Plants: From Design to a New Way of Smart Hybrid Nanomaterials for Green Nanomedicine Applications

International audienc

A graphical method for performance mapping of machines and milling tools

Optimal design of the machining setup in terms of installed machines, cutting tools and process parameters is of paramount importance for every manufacturing company. In most of the metal cutting companies, all choices related to machine eligibility and cutting parameters selection typically come from heuristic approaches and follow supplier indications or base on the skill of experienced machine operators. More advanced solutions, such as model-based and virtual approaches, are adopted less frequently mainly due to the lack of these techniques in grasping the underlying knowledge successfully. Aim of this work is to introduce a synthetic graphical representation of machining centers and cutting tools capabilities, to provide an accessible way to evaluate the feasibility and close-to-limit conditions of the cutting process. Taking inspiration from previous scientific works from the measurement engineering field, a set of 2D and 3D graphs are presented to map machine, tools and process capabilities, as well as their obtainable manufacturing performances and expectable tool life. This approach synthesizes the nominal data coming from different sources (catalogues, database, tool model geometries etc.) and the real cutting tools parameters used during the production phase. Some examples are provided to show the potential of this graphical evaluation in supporting process planning and decision-making and in formalizing the machining setup knowledge. Further developments are devoted to extend the method to other manufacturing processes, including hybrid processes. At the same time, an in-process data gathering software will be integrated for building a solid database that can be used by an autonomous multi-technological process selector, as well as by a pre-process condition advisor in an Industry 4.0 oriented way