Design of a Laccase Bioelectrode Using Multipoint Covalent Immobilization: Behavior Under Different Stress Conditions and Long‐Term Storage

The practical implementation of enzyme bioelectrodes is limited by the inherent lability of proteins, which require mild conditions to maintain both catalytic activity and long‐term stability. The lack of standardized reference parameters and the inherent complexity of biointerfaces also hinder direct comparison among electrochemical enzyme systems. Here, we present a reproducible platform based on the rational structural design of a laccase bioelectrode. Using its crystallographic structure, we performed an in silico evaluation of solvent accessibility and thermal flexibility to identify surface‐exposed lysine residues suitable for multipoint covalent immobilization on aryl‐carboxylic functionalized carbon paper under mild conditions. This strategy creates a simplified biointerface in which stability is integrated as an intrinsic property of the electrode‐enzyme system, eliminating the need for complex nanostructured materials. After 24 h of interfacial protein stabilization, the modified electrode exhibited improved electrochemical kinetics and retained ≈80% of its electroactivity after thermal, mechanical, chemical, and electrochemical stress, and ≈40% after 40 days of storage. The bioelectrode operated as a cathode in both a zinc‐based hybrid cell and a Geobacter sulfurreducens bioelectrochemical system, demonstrating the operational versatility of this approach. This work establishes a structurally guided strategy for the development of robust, reproducible, and comparable biointerfaces for bioelectrochemical applications.