Controlled and reversible modulation of the optical response of noble metal nanoassemblies for biosensing in microfluidic systems – COMONSENS

Noble metal nanoparticles, in particular gold and silver nanoparticles, possess a strong optical response which manifests itself through strong light absorption and - for objects larger than ~20 nm - intense light scattering at wavelengths in the visible and the near-infrared. These phenomena are associated to the plasmon resonance of the particles and are very sensitive to the immediate environment of the structures. A strong modulation of the optical response can be achieved by the assembly of several particles. In the case of molecularly functionalised particles in liquid suspension, such assembly may be readily obtained through biomolecular interactions.

The COMONSENS projects aims to (1) control the modulation of the optical response of self-assembled noble metal nanostructures, (2) make this modulation reversible and sensitive to biomolecular interactions, (3) harness the optical response for the detection of individual assemblies inside microfluidic systems and (4) trap and manipulate noble metal nanoparticles and their assemblies using electric fields (dielectrophoresis) in order to enhance their optical signal. The project combines design and synthesis of functionalised metal nanoparticles, biomolecular self-assembly, the spectroscopic and microscopic investigation of particles and their assemblies in suspension and at the single-object level, the study of the interaction of metallic nano-objects with variable electric fields and design and fabrication of microfluidic systems that integrate particles, electrodes and optics.

We will mainly focus on question of fundamental nature, in particular the stability of functionalised particles at very high dilution in aqueous and biological media, the understanding and control of the optical response of the assembly as a function of their structures obtained through self-assembly and through dielectrophoresis, and the implementation of microsystems suited to the constraints of optical detection. Beyond these question, the COMONSENS project opens up the possibility of miniaturised methods for biosensing that may offer a triple selectivity (biochemical, electrical and optical) as well as high sensitivity.