Enzyme-Induced Transition of the Morphology of Polyelectrolyte Complexes

Polyelectrolyte complexes (PECs) can exist as liquid coacervates or solid precipitates with triggers such as salt, pH, or temperature driving transitions. However, it is unclear how enzymatic chain scission reorganizes solid PECs and alters their mechanics. We probed cellulase-mediated remodeling of solid PECs formed from carboxymethyl cellulose (CMC) and short or long poly(diallyldimethylammonium chloride) (PDADMAC). Turbidity and microscopy showed that short PDADMAC/CMC complexes decreased in turbidity and became liquid-like as enzyme dose and time increased. In contrast, long PDADMAC complexes exhibited a transient turbidity increase at high cellulase concentration and formed droplet-like phases consistent with competing PDADMAC/cellulase coacervation. Zeta potential supported cellulase binding to PDADMAC, which reduced the positive charge available for CMC bridging. Rheology showed dose- and time-dependent softening, while long PDADMAC remained more elastic and relaxed more slowly. Thus, the enzyme dose and polycation length jointly control the kinetics of coupled structural and mechanical transitions in solid PECs.