Our objective is to exploit the whole set of plasmonic processes (field enhancement, heat and hot electron generations) to identify, detect or modify bio-objects (biomolecules, cells) or biological processes to answer to specific biomedical issues.

We focus on three different topics:

1. The observation of biomolecular interactions to enhance the detection of biomarkers and the disease diagnosis

We will use the field enhancement locally produced by the plasmon to enhance the Raman signal from molecules located close to the nanoparticle surface. This effect known as Surface Enhanced Raman Scattering (SERS) has proven its efficiency to detect molecules at very low concentrations (nM or pM Range). SERS biosensors were proposed and the proof of concept were given for the detection of analytes as pollutants, toxins or biomarkers. However, to be efficient a biosensor needs to be specific to one analyte especially if it is present in a biological medium. The specificity is provided by a bioreceptor having affinity with the analyte. To improve the sensing performances, it is of first importance to understand the bioreceptor/analyte interaction. It is therefore important to know how the interaction occurs and if the interaction induces a modification of the bioreceptor conformation.

Our objective is then to provide a better understanding of the biomolecular interactions using SERS. As SERS provides the analyte identification and information of molecular structures, one can have access to any conformation modifications induced by the interaction and thus monitor the interaction.

To investigate the interaction mechanism, we will focus on aptamers (single strand DNA) specific to disease biomarkers (proteins, miRNA) to develop biomedical applications (aptasensor). 

2. The design of a nanoheater to locally destroy some cells and to treat cancer by hyperthermia

The plasmon excitation induces a temperature increase in the nanoparticle and the generated heat can be transferred to the surrounding medium. The nanoparticle becomes a nanoheater usable for hyperthermia. Temperature increases of several degrees were measured for nanoparticles in solution.

Our objective is to correlate the heat generation with the plasmon properties of nanoparticles of different materials and geometries in different environments on a wide spectral range (from visible to near-IR range).

For medical applications, we need to take into account the nanoparticle fate inside the body. As the nanoparticles will be in contact with biological media (blood), they will interact with biomolecules before reaching their target (tumors for instance). We will study the thermoplasmonic effect in biological media and the influence of bio-corona on heat generation will be determined. We will determine the best conditions to get the highest heat generation in biological media. Finally, we will internalize nanoparticles covered by a bioreceptor in cancer cells to destroy them by hyperthermia

3. The generation of hot electrons to enhance biochemical reactions

The enhancement of chemical reactions via the plasmon excitation is a promising new approach in chemistry but limited to organic transformations. The plasmon excitation induces the excitation of hot electrons with high energy that can be transferred to molecules to form radicals or change the oxidation state of catalyst grafted at the nanoparticle surface and induced catalytic reaction. As biochemical reactions are based on oxido-reduction processes (electron transfer between reactants), we then propose to use this plasmon effect to mediate and enhance biochemical reactions and biochemical process.