Since 2004, Jean-Christophe Valmalette has been Professor in Physics, Université de Toulon (France), IM2NP Institute CNRS, Department of Materials and Nanoscience. Starting in 2005, he coordinates the Nanoscale Raman Project for the IM2NP Institute in collaboration with microelectronics companies. His group is using a Scanning Probe Microscope associated with a Raman spectrometer in a lateral configuration. This project is focused on the enhancement effects obtained by SERS substrates (applied to Self-Assembled Monolayers) and tailored probes (optical nano-antenna) obtained by bottom-up approaches for Tip Enhanced Raman Spectroscopy (TERS) applications.

Since 2010 he is also working on bio-inspired capture of light using Raman and hyperspectral spectroscopies. He firstly evidenced a photo-induced charge transfer mechanism occurring in biological interface and suggested for the first time a photosynthesis-like process in insect (Nature News 2010). More recently, he elucidated the capture of light by diatom frustules related to their multiscale nanostructured silica frustules.

KeyWords : Nano-Raman, Plasmonic Supracrystals, Bioinspired Materials, Biophysics, SERS and TERS,  

Selected Recent Papers :

Romann, J; Valmalette, J-C; Royset, A; Einarsrud, M-A, Optical properties of single diatom frustules revealed by confocal microspectroscopy, Optics Letters 40, 5 (2015) DOI:10.1364/OL.40.000740.

Valmalette, JC; Tan, ZQ; Abe, H; Ohara, S, Raman scattering of linear chains of strongly coupled Ag nanoparticles on SWCNTs, Scientific Reports 4, 5238 (2014) DOI: 10.1038/srep05238.

Sato, K; Arai, M ; Valmalette, JC; Abe, H. Surface Capping-Assisted Hydrothermal Growth of Gadolinium-Doped CeO2 Nanocrystals Dispersible in Aqueous Solutions, Langmuir 30, 40 (2014) DOI: 10.1021/la502861k.

Lin, Y.-P., Ksari, Y., Prakash, J., Giovanelli, L., Valmalette, J.-C., & Themlin, J.-M. Nitrogen-doping processes of graphene by a versatile plasma-based method. Carbon, 73, 216-224 (2014). DOI: 10.1016/j.carbon.2014.02.057.

Hashishin, T; Tan, ZQ; Yamamoto, K; Qiu, N; Kim, J; Numako, C; Naka, T; Valmalette, JC; Ohara, S; Quenching ilmenite with a high-temperature and high-pressure phase using super-high-energy ball milling, Scientific Reports 4, 1038 (2014) DOI: 10.1038/srep04700.

Sato K., Yokoyama Y., Valmalette J.C., Kuruma K., Abe H., Takarada T. "Hydrothermal Growth of Tailored SnO2 Nanocrystals" Crystal Growth & Design 21, 1685 (2013) DOI: 10.1021/cg400013q

Brat P., Valmalette J.C., Mertz C., de Souza G., Dombrovski A., Capovilla M., Robichon A., "Analysis of carotenoid compounds in aphids by Raman imaging and mass spectrometry" Nature-ProtocolExchange (2012) doi:10.1038/protex.2012.047

Valmalette, J. C., Dombrovsky A., Brat P., Mertz C., Capovilla M., Robichon A."Light- induced electron transfer and ATP synthesis in a carotene synthesizing insect" Scientific Reports 2, 579, (2012) doi:10.1038/srep00579

Raman investigation in a carotenoids synthesizing insect: First evidence of capture of light and light electron transfer by animal.

The bio-inspired capture of light for energy mass production is a challenging task for the next decades. The photosynthesis is considered as the main mechanism among biological systems able to capture energy from the sunlight. It can be considered roughly as a long chain of photo-induced electron transfers from pigments to the molecular machinery to in fine synthesize ATP, the energy source of all known cells. Recently, we reported a light-induced electron transfer and photo dependent ATP synthesis in an insect [1], the pea aphid. This mechanism appears as an archaic photosynthesis system consisting of photo-emitted electrons that are in fine funnelled into the mitochondrial reducing power in order to synthesize ATP molecules. Our results, based on Raman investigation techniques, have attracted much attention [3] since this is the first report of direct capture of light related ATP synthesis by an insect.

The aphid pigments involve carotenoid genes well defined in chloroplasts and cyanobacteria and amazingly present in the aphid genome, likely by lateral transfer during evolution. The abundant carotenoid synthesis in aphids suggests strongly that a major and unknown physiological role is related to these compounds beyond their canonical anti-oxidant properties.

Because strong carotenoid concentration was observed especially in the green and orange larval forms (despite a high level of variation between individuals in the same colonies when food resources are declining), we tried to unravel some putative physiological functions beside their canonical anti-oxidant properties. We investigated the hypothesis that the photon energy might excite the π delocalized electrons of the carotene polyene structure and trigger an electron transfer to acceptor molecules. Adult aphids (green, orange and white phenotypes) and larvae from orange mothers were placed in dark or left in light photoperiodicity (18/6 hours). Furthermore, these conditioned aphids were returned under light photoperiodicity (18/6 hours) after a dark episode. The striking data show that ATP synthesis is sensitive to light, but differs among the orange (marked effects), green (little effects likely because a strong lipid load in this variant acts as a metabolic reserve) and white phenotypes (no change).

We demonstrated that the ability to capture light involves carotene molecules amazingly synthesized by pea aphid as confirmed by its genome study. Nature News [3] has titled "photosynthetic-like insect" but the capture of light by insect is due to a mechanism different from plant photosynthesis and the mechanism is not yet elucidated.

[1] Valmalette J. C. et al. Sc. Reports 2 2012.
[2] Brat, P. et al. Nature Protocol Exchange 2012
[3] Lougheed K., Nature News 2012
[4] Moran N. Science 2011