Enhancing\nStrawberry Freshness: Multifunction Sustainable\nFilms Utilizing Two Types of Modified Carbon Nanotubes for Photothermal\nFood Packaging

Currently,\nantimicrobial films with stable and efficient antibacterial\nactivities are receiving considerable attention in the food packaging\nindustry. Herein, a chemically/physically linked konjac glucomannan–sodium\nalginate (KGM–SA)@carbon nanotubes (CNTs)/Fe<sup>3+</sup> composite\nfilm with outstanding resistance to ultraviolet radiation, oxidation,\nand bacteria, as well as excellent photothermal effects and mechanical\nproperties, was successfully prepared using a solvent flow method.\nTannic acid-modified carboxyl-functionalized CNTs (TCCNTs), l-cysteine-modified carboxyl-functionalized CNTs (LCCNTs), and Fe<sup>3+</sup> were incorporated into the prepared film. The film structure\nof KGM–SA@CNTs/Fe<sup>3+</sup> was characterized using various\nmethods, confirming the formation of a dual-cross-linked network through\nmetal-coordination bonds and hydrogen bonding. This unique structure\nendowed the film with excellent water vapor permeability (3.58 g mm/m<sup>2</sup> day kPa), water resistance (water contact angle = 93.66°),\nand thermal stability. Further, the film exhibited outstanding photothermal\nconversion efficiency and stability under near-infrared irradiation\n(300 mW/cm<sup>2</sup>) as well as excellent bactericidal properties\nagainst <i>Staphylococcus aureus</i> and <i>Escherichia\ncoli</i>, achieving a bacterial inhibition rate of >99%. In\na\nstrawberry preservation experiment, the KGM–SA@CNTs/Fe<sup>3+</sup> composite film exhibited remarkable preservation effects,\nextending the shelf life of strawberries by 4–6 d. Thus, this\nphotothermal antibacterial film offers a new approach for the application\nof CNTs in food packaging.