Effect of gold nanoparticles size and buffer solution on their interaction with fixed cells.

Fluorescence imaging is one of the most commonly used diagnostic techniques which allows the localization of biomolecules inside cells. However, the strong overlap between intrinsic fluorescence and emitted signal from the protein of interests is one of the most important limits related to this technique. In this context, numerous studies have confirmed the strong ability of plasmonic nanoparticles to alter the fluorescence signal, making them good candidates for the optical contrast enhancement [1,2]. Nevertheless, there have been conflicting reports on the role of AuNP size and buffer solution on their effect on the fluorescence and the interaction with cells. We therefore thought to extensively investigate the AuNP size/buffer solution-fluorescence bioimaging relationship. Here we review the effects of nanoparticle size variation on the contrast enhancement in laser scanning confocal microscopy imaging modality, to detect the endothelial nitric oxide synthase proteins in lungfish gills. we used AuNPS with sizes ranging from 5 to 100 nm. We demonstrate that smaller AuNPs show greater optical contrast enhancement and easier biodistribution than larger one [3]. we have also demonstrated an increase of the affinity between nanoparticles and cells thanks to the optimization of the optical contrast by 3-fold, simply by using a different buffer [4].