Mechanical forces can be utilized to distort the shape of biomolecules, thereby explore their elastic properties. Furthermore, mechanical forces can be used to alter the rate of biochemical transitions, thereby access energetic and kinetic parameters of reactions. We use optical tweezers and scanning probe microscopies to investigate various biomolecular systems ranging from cytoskeletal filaments to nucleic acids and supramolecular complexes. Force-driven unfolding and refolding of the giant muscle protein titin provides a unique insight into how this molecule may be involved in the mechanics and regulation of muscle contractility. Nanomanipulation of methylated DNA allows us to dissect possible epigenetic mechanisms. Finally, the mechanical manipulation of bacteriophages gives a glimpse at the mechanisms of viral capsid architecture and the triggering of viral DNA ejection.

A major obstacle of using graphene for nanoelectronic applications is its significant vulnerability of contamination by adsorbed molecules. Various polymers commonly used for device processing leave residual traces on graphene, leading to doping effects and band structure modifications. We present an experimental study of time dependent ozone treatment on post-process epitaxial graphene using both electron transport measurements and resonant micro-Raman spectroscopy. We focus on a systematic analysis of residual polymer decomposition on the epitaxial graphene on SiC substrate. It was found that graphene could be effectively cleaned by ultraviolet (UV)/ozone treatment after nanofabrication from residual lithographic polymers. This procedure improves the charge carrier mobility, almost by a factor of two for strongly contaminated samples, decreases the doping level and does not introduce defect inside the graphene lattice. It was found that epitaxial SiC graphene is extremely stable when exposed to radical oxygen atoms. We ascribe this effect to the substrate topography, which significantly affects the graphene stability under UV/ozone treatment. Our calculations reveal that surface roughness of the SiC substrate can change the energy gain from epoxy group adsorption by a few tenths of electron volts.

Référence : V.S. Prudkovskiy, K.P. Katin, et al., Carbon, 109, 221 (2016) http://dx.doi.org/10.1016/j.carbon.2016.08.013

Fluorescent nanodiamonds (FNDs) represent a key component in recent development of ultra-high precision optical resolution techniques. FNDs can accommodate various color centers, including bright silicon-vacancy center (SiV) and nitrogen-vacancy (NV) center – extremely photostable crystal lattice defects emitting in near-infrared region. Electron transitions among NV quantum states can be influenced by very weak external electric or magnetic fields, which have been utilized for construction of various types of probes and nanosensors.
For application of FNDs in biological systems and for achieving high target selectivity, a precise control of particles’ bionanointerface is urgently needed. Different synthetic approaches towards bioapplicable FNDs will be presented. Creation of different antifouling polymeric coatings on FNDs, their physico-chemical comparison, bioorthogonal modification with various (bio)molecules using click chemistry, and imaging of cancer cells using these conjugates will be shown. Chemical aspects influencing interactions at FND surface will be discussed.

Nanoplasmonics is an active field of research, based on the use of noble metal nanoparticles. Such nano-objects can behave as efficient nanosources of light or nanosources of heat under illumination at their plasmonic resonance wavelength. Many applications of nanoplasmonics have been developed these last two decades, e. g. in nanochemistry, biosensing, microscopy, biomedicine, magnetic recording, etc.

This presentation will focus on nanoplasmonics using noble metal nanoparticles as nanosources of heat, an area of research called thermoplasmonics. The importance and impact of this field of research will be presented through an overview of all the applications, with a particular and critical focus on photothermal cancer therapy, the most promoted application in thermoplasmonics. Then, some of the applications developed in thermoplasmonics at the Institut Fresnel in Marseille will be presented, from physics to chemistry and cell biology.

Two-dimensional materials are currently a topic of widespread research interest, in areas both fundamental and applied. These are crystalline materials consisting of a single layer of atoms, although very thin, few-layer materials are also considered 2D or quasi-2D. Since the isolation of graphene in 2004, a wide variety of 2D materials have been found, with electronic properties ranging from metallic to insulating, and a variety of applications have been suggested. In this talk I will discuss the basic properties of 2D materials (including graphene, silicene, hexagonal boron nitride, black phosphorus, and the transition metal di-chalcogenides (TMDCs) such as molybdenum disulfide), their electromagnetic models, and various applications, including interactions with quantum emitters and valley pumping scenarios.