A stepwise in situ construction of ZnO@ZIF-8 Core-Shell structures on lignocellulosic substrates for durable antifungal performance

As a highly valued natural lignocellulosic biopolymer, bamboo plays a critical role in developing sustainable material systems. However, when exposed to rainwater, this biopolymeric substrate is highly susceptible to fungal degradation, making it difficult for traditional fungicides to retain long-term efficacy. Their inevitable leaching weakens antifungal performance and raises environmental concerns, while conventional treatments often compromise the mechanical integrity of the lignocellulosic structure. Therefore, developing green, durable, and substrate-compatible antifungal technologies is essential. Nanoscale zinc oxide (ZnO) is a promising inorganic antimicrobial agent due to its multi-mechanism activity and favorable biosafety, yet issues like agglomeration, poor stability, and rapid ion release limit its long-term performance. To overcome these drawbacks, a stepwise in-situ construction strategy is introduced, where a ZnO layer is first grown as both the core and zinc source to direct ZIF-8 formation, yielding a shell that stabilizes ZnO and ensures sustained Zn 2+ release for long-lasting antifungal efficacy. Comprehensive characterization verifies the successful formation of a compact, crystalline core-shell heterostructure well-integrated with the biopolymer matrix. Mechanical testing confirms that the ZnO@ZIF-8 treatment preserves the intrinsic mechanical properties of the bamboo, maintaining a tensile strength of 96.52 MPa while elevating bending strength by 31.79% to 169.46 MPa. Anti-mold and anti-leaching evaluations further demonstrate excellent durability, maintaining Grade 0 (no mold growth) infection after 14 days of leaching and 28 days of humid-heat incubation. This work presents an efficient, durable, and environmentally friendly antifungal strategy for bamboo, offering valuable insights into the application of metal oxide-MOF composites in bamboo protection.