We report a simple and scalable fluorinated silane-based synthesis that yields aqueous suspensions of optically transparent, monodisperse colloidal particles with programmable internal architecture. The resulting low–refractive-index particles are near index-matched to water, enabling deep three-dimensional optical imaging without solvent exchange. The method provides precise control over particle size and morphology, allowing the fabrication of solid spheres, hollow shells with tunable wall thickness, and colloids with off-centered fluorescent labeling. The latter act as single-particle rotational probes, enabling the direct measurement of rotational dynamics in dense aqueous suspensions. We demonstrate the utility of these particles through real-time confocal imaging of dense crystals and by quantifying rotational Brownian motion at the particle level. This approach establishes fluorinated silane colloids as a general aqueous system for studying structure, dynamics, and mechanics in soft condensed and biological matter with full optical access.
Zhu et al. (Mon,) studied this question.