Giant hyaluronan polymer brushes display polyelectrolyte brush polymer physics behavior

We report on the polyelectrolyte brush behavior of extra-large hyaluronan polymer brushes (~15 microns) recently developed using an enzyme-mediated growth process. The giant height of the brushes enables direct characterization of 3D structure and time-dependent behavior. In this study, we explored the stimulus response of the brush to ionic strength and solvent changes. The brush displays classic osmotic brush and salted brush regime behaviors. In poor solvent (ethanol), the brush collapse by 96%. The collapse is rapid when changing from a good to a poor solvent, but re-expansion is extremely slow when changing back to a good solvent. The observed brush behavior is similar to that seen for smaller polyelectrolyte brushes, indicating that these ultra-thick brushes will serve well as model systems to study more complex phenomena, including dynamics, through confocal microscopy