Xanthan gum/hydroxypropyl methylcellulose/carbon quantum dots composite to enhance mango shelf life by triggering metacaspase-dependent apoptosis in Colletotrichum gloeosporioides.

Colletotrichum gloeosporioides, the primary fungal pathogen responsible for mango anthracnose, causes significant economic losses. Hence, we developed a xanthan gum/hydroxypropyl methylcellulose (XG/HPMC) film incorporating Dictyophora echinovolvata carbon quantum dots (DE-CQDs). These green-synthesized DE-CQDs are 2 nm spherical nanoparticles with good crystallinity and thermal stability, featuring functional groups such as -OH, -COOH, -NH₄, and -SO₃H, which enhance hydrophilicity, solubility, and charge properties. The negative charge of DE-CQDs, as evidenced by zeta potential measurements, enhances their dispersibility and inhibits aggregation, thereby contributing to the film's augmented UV-blocking and water vapor transmission characteristics. DE-CQDs inhibit C. gloeosporioides growth through a unique mechanism, inducing metacaspase-dependent apoptosis and causing ROS accumulation without DNA fragmentation. When incorporated into the XHC film, DE-CQDs improve UV-blocking by 30 % at 400 nm, enhance water vapor transmission, and increase water contact angle. The XHC film significantly reduces mango decay (decay index: 0.35 ± 0.05 to 0.21 ± 0.05) and boosts vitamin C retention (from 30 % to 61 % over 7 days), effectively extending shelf life and preserving nutritional quality. Among the XHC films, XHC6 shows the best overall performance. Thus, DE-CQDs serve as functional fillers in biodegradable, environmentally friendly packaging films, offering a novel solution for mango disease prevention and control.