Synthesis of colloidal particles which are sterically stabilized in water and at the same time isorefractive in aqueous dispersion has been achieved by copolymerizing a fluoracrylate monomer with a PEG-macromonomer. Colloidal stability against salt addition and freeze-thawing cycles is demonstrated, indicating that the particles consist of a core of fluoroacrylate and a stabilizing surface layer of grafted PEG. To test the performance as a model system for studies of colloidal vitrification in aqueous media, the dynamics of a binary mixture of these particles with a size ratio of 0.8 and a number ratio of 1.3 (small : large particles) were studied in an isorefractive mixture of water and DMSO (≈ 11 mol % DMSO). The characteristic features of a system close to the glass transition were observed in the density density autocorrelation function f(q, τ) as measured by DLS. However, the glass transition occurred at an unexpectedly low volume fraction of 0.262. This discrepancy correlates with an unusually large difference between TEM and DLS radii and is explained by the presence of a rather extended hairy PEG surface layer.