High-efficiency restoration of stone cultural relics via immobilized carbonic anhydrase on magnetic graphite oxide.

Stone cultural relics face persistent threats from weathering and erosion processes, whereas conventional restoration techniques frequently induce material incompatibility and secondary damage. Enzyme-induced calcium carbonate precipitation (EICP) offers a solution by forming protective layers, but free enzymes suffer from short lifespan and poor stability. Therefore, this study proposes a strategy that the α-carbonic anhydrase from Helicobacter pylori strain 26695 (HpCA) was immobilized on magnetic graphene oxide (mGO) to obtain the immobilized enzyme mGO@HpCA for stone relic restoration. mGO serves as both a stabilization matrix for CA and a nanoscale dispersant for uniform enzyme distribution, while also providing nucleation sites for denser calcium carbonate layers. Compared to free enzymes, mGO@HpCA achieved 1.87 times greater mineral mass accumulation after 48 h, reduced water absorption by 75.7 % and air permeability by 27.7 %, and improved acid resistance, with 49.5 % less mass loss after 120 h of acid immersion. These features effectively safeguard stone relics against rainwater, soluble salts, and climate change effects. This approach provides an efficient, eco-friendly, and non-destructive conservation method.