Bioactive galactose-branched polyelectrolyte multilayers and microcapsules: Self-assembly, characterization, and biospecific lectin adsorption

We describe the fabrication of multilayers and microcapsules with biologically designed targeting activity using chemoenzymatic synthesized carbohydrate-branched polyelectrolytes. A novel cationic D-galactose-branched copolymer [poly(vinyl galactose ester-co-methacryloxyethyl trimethylammonium chloride), PGEDMC] is alternated with poly(styrene sulfonate) (PSS) to form thin multifilms by the layer-by-layer (LbL) technique on such different solid surfaces as quartz slides, poly(ethylene terephthalate) (PET) films, silicon wafers, and polystyrene (PS) microparticles. The experimental protocols were first optimized on flat, smooth silica substrates using UV-vis, contact angle, and atomic force microscopy (AFM) measurements. The film properties of PGEDMC/PSS multilayers are modified by varying polyelectrolyte concentration, ionic strength, and counteranion types. Hollow capsules were formed after the removal of colloidal templates; transmission (TEM) and scanning (SEM) electron microscopy were used to verify the LbL process integrity. PGEDMC/PSS planar films and capsules carrying beta-galactose as recognition signals have specific recognition abilities with peanut agglutinin (PNA) lectin rather than concanavalin A (Con A) lectin observed by fluorescence spectroscopy.