Hierarchically porous polysaccharide aerogel with in situ anchored HKUST-1 for humidity-responsive carvacrol release and strawberry preservation.

Excessive moisture sensitivity of pristine HKUST-1 often causes rapid framework collapse and burst release under highly humid conditions, limiting its use as a humidity-triggered carrier for volatile antimicrobials. Here, we report a hierarchically porous composite aerogel constructed by in situ growth of HKUST-1 within a poly (vinyl alcohol)/carboxymethyl chitosan/TEMPO-oxidised cellulose nanofiber network, followed by carvacrol (CAR) loading to obtain PCTH@CAR. This confined growth architecture regulated metal organic framework (MOF) distribution, helped moderate moisture-induced structural disruption, and coupled polymer-derived macropores with MOF micropores, thereby improving cargo accommodation and release control. The cumulative CAR release reached 54.32% after 12 d even at 15% RH, while at 98% RH it reached 34.61% after 2 d and 81.99% after 12 d, with release sustained throughout storage rather than concentrated at the initial stage. The aerogel also showed effective vapour phase antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Botrytis cinerea. In strawberry packaging, PCTH@CAR delayed visible spoilage and reduced weight loss from 20.45% to 2.04% after 8 d, whereas untreated strawberries had already lost marketability by day 4 owing to evident mould growth and softening. These results support in situ grown HKUST-1 within a hierarchically porous biopolymer aerogel as a practical route to non-contact, humidity-adaptive active packaging for postharvest preservation.