Surface bound microgels on the basis of carboxymethylcellulose: preparation <i>via</i> the Ugi reaction and structural investigation using fluorescent and spin labels

A microgel with an average diameter of 368±4 nm was obtained by adding a small amount of polyvinylamine (PVAm) to a 0.3% aqueous solution of carboxymethylcellulose (CMC). The CMC/PVAm microgel particles were deposited on a layer of pure PVAm, which in turn was located on a glass substrate. Four-component Ugi condensation in aqueous solutions at pH 5.0–5.5 was applied to fix the resulted structures. A water-insoluble layer of PVAm gel with CMC/PVAm microgel particles distributed over its surface was obtained. It was shown that at pH 8 the CMC/PVAm gel particles swell, more completely covering the surface of the PVAm gel layer applied to a glass substrate. Fluorescent labels (aminofluorescein moiety) and spin labels (amino-TEMPO moiety) were introduced into the CMC structure in order to monitor this process using fluorescence microscopy and EPR spectroscopy.