Carbon Quantum Dots-Enhanced Polyvinyl Alcohol: A Comprehensive Approach to Food Preservation.

Polyvinyl alcohol (PVA) is a promising biodegradable matrix for food packaging but suffers from high hydrophilicity, high water vapor permeability, and a lack of active functionalities. To overcome these limitations, recent research incorporates zero-dimensional carbon quantum dots (CQDs) as active nanomaterials. This review evaluates the physical, transport, and preservative synergies of CQD/PVA composite matrices. Integrating uniform CQDs reduces matrix wettability through dense intermolecular hydrogen bonding with PVA hydroxyl groups, as evidenced by a 26.16% increase in water contact angle for 3% lemon peel-derived CQDs. Furthermore, the impermeable nanoparticles introduce a classic tortuous-path effect and act as heterogeneous nucleation sites, densifying the network and driving a profound 94.68% decrease in oxygen permeability with just 1% green tea-derived CQDs. Beyond physical barrier optimization, embedded CQDs endow the matrix with robust multiwavelength UV-blocking properties, potent antioxidant radical scavenging, and broad-spectrum antimicrobial activity. These active functionalities effectively suppress oxygen-dependent degradative enzymes, such as polyphenol oxidase, to halt browning, extending shelf life across fruit, bakery, and seafood models. Driven by PET, FRET, and IFE luminescent mechanisms, these composites function as nondestructive, real-time freshness indicators, offering a sustainable, intelligent packaging.