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Synthesis of nanoparticles and photonic nanomaterials

Karine Mougin  karine.mougin@uha.fr

Nanomaterials and nanophotonics

Metal nanoparticles play a central role in nanophotonics, a discipline that studies the interaction of light with matter at the nanoscale. Thanks to their unique plasmonic properties, these nanoparticles can focus light well beyond diffraction limits, enabling the precise manipulation of electromagnetic fields on a very small scale. Their optical properties are particularly sought after : metal nanoparticles have been used for centuries by artists for the luminous colors produced by their interaction with visible light. Today, they are paving the way for numerous innovative applications, such as ultra-sensitive optical sensors, high-speed communication devices, and targeted therapies in biomedicine, high-tech textiles, cosmetics, pharmaceuticals, agri-food, aeronautics, and even automotive.

a. Solutions of colloidal gold nanoparticles of different shapes, TEM images of gold nanoparticles b. Spherical c. Nanorods d. Nano-urchins

Color changing nanomaterials

Smart materials (or active materials) are materials capable of reacting in a controlled manner to external stimuli (temperature, humidity, pressure, etc.). In this case, color-changing materials provide an innovative and relevant response without the need for electronics, batteries, or external power sources. This passive nature gives these materials great autonomy and ease of integration in many contexts, including the most demanding.
Our research therefore focuses on the manufacturing of these active hybrid materials combining polymers and metal nanoparticles to develop color-changing sensors. These materials react to various environmental stimuli by modifying their visual appearance, thus enabling simple, rapid detection without the need for embedded electronics. Manufacturing relies on chemical or photochemical synthesis processes, designed to be more environmentally friendly and more stable over time.

Color-changing sensor : a. Elastomer loaded with colloidal gold nanoparticles under stretching ; b. Polymer loaded with colloidal gold nanoparticles exposed to different humidity levels ; c. Schematic of a polymer that bends after illumination.

Their applications range from sports, with smart clothing, to health, particularly in the medical field (compression stockings, dentistry, surgery, etc.), to the preservation of sensitive products such as food to detect the presence of humidity, to agriculture, to mechanics for local overpressure problems, to printing inks and paint, to robotics, to security, to military and defense applications such as camouflage, etc.

Trace molecules sensors

Nanoparticle-based trace molecule sensors represent a major advance in the field of chemical and biological detection. Thanks to their very large specific surface area and unique physicochemical properties, nanoparticles can detect extremely low concentrations of substances, sometimes down to the nanomolar or picomolar scale. Our research focuses on the development of these optical, electrochemical or plasmonic sensors, which interact selectively with target molecules, resulting in a measurable signal at very low concentrations (trace molecules). These sensors find applications in environmental monitoring, food safety, medical diagnostics, explosives and drug detection, and battery leak detection.

a. Fabrication diagram of a trace molecule sensor, b. SEM image of a gold nanoflower-sensor, c. Optical response of the sensor for the detection of low concentrations of organic molecules.