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

In situ HKUST-1 growth created a hierarchically porous hydrocolloid aerogel. • Polymer macropores and MOF pore domains jointly regulated carvacrol loading and release. • Humidity build-up triggered sustained rather than front-loaded carvacrol release. • Vapour phase carvacrol effectively inhibited bacterial and Botrytis cinerea growth. • PCTH@CAR delayed strawberry deterioration by maintaining texture and water status. 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. Download: Download high-res image (211KB) Download: Download full-size image