Numerous works are based on the design, the elaboration and the study of the optical properties of gold nanoprobes for
potential applications in biotechnologies (bioimaging, biosensing). Among all the possible shapes, it appears that sharp
gold nanostructures exhibit interesting features due to the strong filed generated at their tips ends, making them very
sensitive to the surrounding medium. Here we describe a complete study of PEGylated gold nanoparticles : nanostars and
bipyramids as potential agents for bioimaging. The nanoprobes are first prepared in high yield before functionalization
with a biocompatible polymer. Then, the PEGylated gold nanoparticles are incubated with melanoma B16-F10 cells and
observed using Dark-field microscopy. Results show that the biocompatible gold nanoparticles are easily internalized and
most of them localized within the cells.
We review our work on hybrid gold nanoparticles that are optimized for their bright fluorescence and photobleaching resistance. Our first goal in using gold nanoparticles is to load a large density of photoactive molecules onto a biocompatible nanoplatform. Our second goal is to optimize the molecule-gold nanoparticle interaction to improve the photoactive properties, in particular their photobleaching resistance. In this project gold nanoparticles have typical dimensions in the 50-100 nm that are suitable for in vivo imaging and photodynamic therapy. Their geometrical shapes include nanoshell, spheres, rods, bipyramids and stars.
The use of microfluidic devices for the handling and analysis of suspensions of colloidal gold particles is presented. The plasmonic particles are detected via their resonant light scattering (RLS) in a simple and versatile LED-based dark field illumination geometry. RLS enables both microscopic imaging and microspectroscopy. The measurement of the diffusion coefficient of nanoparticles in this type of devices is demonstrated. Nanoparticles are separated from small (free ligand) molecules in a continuous flow process. Reversible aggregation of functionalized particles is detected in microflow by means of RLS, which opens perspectives for the development of microfluidic bioplasmonic detection schemes.