Modular Assembly of a Biocatalytic Material for Stereoselective C─Si Bond Formation

ABSTRACT Biocatalysis offers sustainable routes to complex molecules, yet translating enzymatic activity into robust, reusable materials remains a major challenge. Here, we report the modular assembly of a self‐supporting biocatalytic material for stereoselective C─Si bond formation using an engineered Rhodothermus marinus cytochrome c (CC). The material was constructed by site‐specific covalent coupling of CC fused with two SpyCatcher domains (SC‐CC‐SC) with streptavidin variants bearing SpyTag domains (STV‐ST), yielding a red, porous enzyme foam with defined hexagonal architecture. The modular STV‐mediated crosslinking strategy enables the formation of carrier‐free materials with high enzyme density and minimal diffusion barriers. The CC foams retained structural integrity and catalytic activity after drying, catalyzing the formation of a chiral organosilicon compound with high enantioselectivity under mild conditions. The enzyme remains active at the extensive gas–liquid interfaces within the foam, effectively combining high catalyst loading with excellent mass transport. The resulting material retains high stereoselectivity (>95% ee), exhibits catalytic performance comparable to previously reported carrier‐based immobilization approaches, and maintains catalytic activity over five consecutive reuse cycles. This immobilization concept establishes a generalizable platform for fabricating biocatalytic materials from monomeric enzymes and expands the scope of enzymatic C─Si bond formation toward scalable, sustainable synthesis.