Sphingolipid Gel/Fluid Phase Transition Measurement by Integrated Resonance Probe Light

International audienceThe paper describes nanophotonic sensors realized by way of inexpensive organic processes. As hybrid silica/polymer resonators, they are suited to detect biological molecules in gel/fluid phase transition at infinitesimal concentrations (sphingomyelin lipids). Such a family of photonic structures is made of specific amplified deep UV210 photoresist-polymer waveguides coupled by a sub-wavelength gap with various racetrack micro-resonators. Thus, temperature dependent wavelength shifts characterizing the optical resonances of the device have been evaluated, highlighting a low thermal feature of the sensor, which is advantageous for this specific application. With an adapted vesicle lipid deposition process, specific in biology, together with an apt experimental thermo-photonic protocol, the dynamic evolution of the sphingomyelin lipid phase transition has been followed and assessed. The ability to detect their gel/fluid transition phase and melting temperature has been demonstrated with a mass product factor value 10^7 lower than that of classical methods as differential scanning calorimetry. The global equilibrium regimes of the coupling effect of resonances and the scattered part of the light are clearly highlighted as markedly modified by the dynamic of the sphingomyelin during its own phase transition