Colorimetric Analysis Platform of Porous Nanoparticles for Biosensing Application Based on Gires-Tournois Resonator

Abstract

Nanophotonic resonators paves the way for label-free bright-field imaging and quantification of nanoscale bioparticles by confinement of light in subwavelength volumes. Direct colorimetric sensing and imaging of viral particles (VP) using porous nanoparticles usually a challenging task owing to their nanoscale size and varying Refractive index (RI) which needs high resolution microscopy with tailored system and complicated methodology. Gires Tournois (GT) resonator, a three stacked photonic structure that enables slow light phenomenon in the resonant layer by slowing down the velocity of the reflected light prior to the incident light being reflected. Vivid colorimetric visualization and quantification of various nanometer-sized VP with low RI is visible through a conventional Microscopy where VP clusters and background shows distinctive color difference depending on the diameter, RI, gap, and layer on the surface of the resonator. Porous nanostructured Particles have been employed extensively for bio-sensing applications of various analytes owing to their wide surface area and excellent optical properties. However because of the nanoscale diameter and pore size of the particles, surface functionalization of analytes binding becomes a complex issue which deteriorates and limits the performance of the label-free biosensor. Here, an effective and robust approach is reported for label-free colorimetric biosensing utilizing Mesoporous Silica nanoparticles (MSN) based on GT resonator which provides enhanced light-matter interaction for surface biofunctionalization with the analytes.