Minimalist Second-Sphere Engineering with Polyvinyl Alcohol Drives Cooperative Hydrolysis in Zn(II) System

Abstract

First sphere engineering has enabled potent artificial phosphatases, but strategies that generate enzyme-like second-sphere effects with simple disordered materials remain limited. Here we demonstrate that partially hydrolyzed polyvinyl alcohol (PVA80, 80% hydrolyzed) acts as a minimalist soft matter scaffold that amplifies the hydrolytic activity of hydrated Zn(II). Rather than functioning as a static host, the amphiphilic polymer undergoes substrate induced reorganization to form hydrophobic microdomains. These microdomains enrich the substrate and organize labile Zn(II) into cooperative catalytic networks that exhibit cooperative kinetics with a Hill coefficient of 4.2, and selectivity for hydrophobic substrates. The catalyst has an apparent Michaelis-Menten constant (KM) of 0.52 mM and a catalytic efficiency (kcat/KM) of 1.86×10-2 M-1 s-1, approaching the performance of synthetic Zn(II) phosphoesterases based on Zn(II) complexes. Solvatochromic and solvent isotope analyses indicate that rate enhancement arises from coupled hydrophobic partitioning and polymer assisted proton transfer. In contrast, Ce(IV) retains Michaelis-Menten behavior upon polymer addition, with PVA80 primarily enhancing substrate availability without inducing cooperative activation. These findings show that enzyme like behavior can emerge from disordered polymer interfaces, and simple polymer chains can provide an accessible strategy to modulate metal reactivity without complicated synthesis.