Topology-Enabled Star Polyelectrolyte Coacervates for Adaptive and Robust Enzyme Immobilization

Enzyme immobilization in solid porous supports often faces a trade-off among enzyme loading, mass transport, catalytic activity, and operational stability. Here, we report star polyelectrolyte coacervates (SPEC) as a liquid-like immobilization platform formed by simple mixing of oppositely charged star polyelectrolytes. The multivalent star topology organizes the coacervate into a compact yet dynamically adaptive network, enabling near-quantitative enzyme capture while preserving local reconfigurability and reaction-coupled transport. Using lipase as a model enzyme, SPEC achieved 97 ± 2% loading efficiency and accelerated apparent catalytic kinetics by about one order of magnitude. Michaelis–Menten analysis showed a decrease in apparent Michaelis constant  (K_m ) from 0.419  mM to 0.196 mM and a 16.3-fold increase catalytic efficiency (k_cat/K_m, from 37.5 M^-1 s^-1 to 613 M^-1 s^-1 ). Beyond activity enhancement, the star architecture generated a compact, low-polarity microenvironment that strongly suppressed ion penetration. Even in near-saturated NaCl solution (4.88 M), the internal salt concentration remained only 0.32 M, corresponding to an ion-partition coefficient of 0.07. This topology-enabled ion exclusion preserved enzyme structure and hydration under ionic stress, allowing SPEC-immobilized lipase to retain about 80% activity in 1.5 M NaCl, whereas free lipase was nearly deactivated. SPEC also remained robust against pH, temperature, and organic-solvent perturbations and supported continuous-flow biocatalysis for approximately 200 h. Generality was demonstrated across lipases from multiple sources, alkaline phosphatase, and trypsin. These results establish SPEC as adaptive interfacial polymer assemblies that couple efficient molecular transport with microenvironmental protection, providing a general strategy for high-performance biocatalysis under demanding conditions.