|Gold nanoparticles for plasmonics and medicine|
Leader: Sylvie Marguet
Participants: Aurélie Habert, Jérôme Caron (Master-2), Mohammad Khaywah (Post-doc)
Summary: Our objective is to take advantage of the light-matter interaction in nanohybrids, composed of colloidal gold nanoparticles (AuNPs), whose morphology is optimized, to generate light, heat or charge carriers, depending on the targeted application*.
… for PLASMONICS: since 2008:
Collaborations : CEA-SPEC; L2n-Troyes; ISMO-Orsay; IS2M-Mulhouse; ILM-Lyon, ...
Plasmonics is a discipline at the interface between physics, chemistry and biology. The excitation of the plasmon resonance of a metallic nanoparticle (NP) generates very intense electromagnetic fields, confined to the surface of the NP, which can be used to enhance or initiate a photochemical reaction in a nearby "chromophore". The confinement of the electromagnetic field around a colloidal NP, monocrystalline and non-rough, is greater than that around the same object manufactured by nanolithography. The relaxation of the plasmon, which accompanies this amplification effect, occurs according to ultra-fast relaxation paths, in competition with each other. Their relative importance depends on the morphology of the NP, its "close" environment and the irradiation mode. Thus, gold nanoparticles can behave as nanosources of light, heat or charge carriers (electron, hole), depending on the predominant deactivation path. In terms of morphology, it is the size, the presence of peaks and the aspect ratio (surface/volume) of the NP that matter. The environment refers to both the "chromophores" adsorbed on the surface of the NP and in particular their energy levels (HOMO-LUMO for a molecule or VB-CB for a semiconductor) as well as the possible presence of a layer at the interface (surfactant residues, insulating layer...). Finally, the irradiation mode, continuous or pulsed at different time scales from micro to femto-second, is also a key parameter for the observation of these three types of nanosources.
We synthesize gold nanoparticles (Au-NP) by careful control of their morphology (size, shape) and crystalline structure. Some of these AuNPs are only produced in a few laboratories around the world. Microplates (triangular, hexagonal or disc-shaped), which are atomically flat, are promising for the FIB nanofabrication of monocrystalline, not otherwise accessible. A large number of protocols are being developed for various purposes: i) replacement of the initial surfactant by other more appropriate molecules; ii) homogeneous dispersion of NPs on various supports; iii) self-assembly in one (1D), two (2D), or three dimensions (3D) to produce "hot spots"; iv) coating by a layer of silica of variable thicknesses. Environmental and energy applications are envisaged in the longer term through the synthesis of multimetallic nanoparticles of the Au@X type (with X= Pd, Pt, Au, Ag or TiO2) which combines a plasmon component (Au) and a catalyst for plasmon catalysis and plasmon-induced photochemistry.
… for MEDICINE: since 2018:
Collaborations : LPQM-CentraleSupelec, LAC-Orsay, CEA-SPEC, PPSM-ENS, ...
We produce Au@silice core-shell nanoparticles that are promising contrast agents for many medical imaging techniques (photoacoustics, dark field scattering, multi-photonic luminescence, high frequency ultrasound, quantitative phase contrast, computer tomography...). In this sense, the recently accepted ANR SINAPSE project aims to develop a new class of nanoparticles for neuronal imaging (coord François. Marquier). Gold nanoparticles are excellent sensors (e.g. pregnancy test) of the LSPR, SERS, Fluorescence, or Pressure type. In the field of phototherapy, gold nanoparticles with a high aspect ratio (length/thickness), such as wires and platelets, are very interesting because they can be excited by infrared photons in the first windows (I,II,III,IV) of the transparency of biological tissues. Plasmon-induced heat generation (PTT; photothermal therapy) and more recently the generation of R.O.S. (reactive oxygen species) from gold nanoparticles alone (i. e. without photosensitizer) is an original approach to treat tumours, especially in the absence of oxygen, when conventional PDT (photodynamic therapy), based on the use of porphyrin molecules in the triplet excited state, cannot work. The HEPPROS project (cancer plan) aims to study the generation of heat and R.O.S. such as 1O2, OH., O2.-, H2O2 for various morphologies of gold nanoparticles and thus better understand the complex transient mechanisms involved at the AuNP/molecular adsorbate interface (coord Bruno Palpant).
Funded Collaborations (past and present) :
“SINAPSE” (2019-2021) ANR : Silicon Carbide NanoProbes and optical Signal Enhancement for intracellular transport investigation in 3D cultures of neurons
“HEPPROS” (2018-2020) Plan Cancer : Highly Efficient Plasmonic Production of Reactive Oxygene Species for Photodynamic Therapy:
“HAPPLE” (2013-2017) ANR : Hybrid Anisotropic Plasmon-Photonics for Light Emission:
“COSSMET” (2014-2015) DIM Nano-K :
Publications : up-to-date list.
"From plasmon-induced luminescence enhancement in gold nanorods to plasmon-induced luminescence turn-off: a way to control reshaping"
“Near-Field Localization of Single Au Cubes, a Predictive Group Theory Scheme.”
“Fano Transparency in Rounded Nanocube Dimers Induced by Gap Plasmon Coupling”,
“Two-photon luminescence of single colloidal gold nanorods: revealing the origin of plasmon relaxation in small nanocrystals”,
“Engineering the emission of light from a scanning tunneling microscope using the plasmonic modes of a nanoparticle."
“An Electrically Excited Nanoscale Light Source with Active Angular Control of the Emitted Light”
“Mapping the Electromagnetic Near-Field Enhancements of Gold Nanocubes”.
“Spatial Confinement of Electromagnetic Hot and Cold Spots in Gold Nanocubes”.