Quaternary-ammonium chitosan/Sericin-modified carbon nanotubes Photothermal coatings: A reusable and sustainable chemical-free seed disinfection strategy

The increasing global demand for food and the adverse environmental impacts of excessive agrochemical use highlights the urgent need for sustainable and scalable seed treatment technologies. This paper reports a novel photothermal seed coating (QC@SCCNTs) with high biocompatibility, exceptional photothermal efficiency, and notable reusability, serving as an effective alternative to conventional chemical treatments. The coating consists of sericin-functionalized carboxylated carbon nanotubes (SCCNTs) electrostatically complexed with quaternary ammonium chitosan (QC), forming a composite film (QS film). Under 808 nm near-infrared (NIR) irradiation, QC@SCCNTs demonstrated antimicrobial efficacies exceeding 97 % against six pathogenic microorganisms, including prominent pathogens such as Aspergillus flavus and Fusarium solani. Applied to red kidney bean and pakchoi seeds, the coating effectively eliminated microbial contamination, increasing the germination rate of red kidney beans from 55.56 % to 91.67 %, and promoting seedling height from 14.48 cm to 41.01 cm. The QS film exhibited exceptionally gas barrier properties and mechanical strength, and completely degraded within just three days of soil burial. The coating retained antimicrobial performance over two reuse cycles after removal and washing. These findings demonstrate the potential of QC@SCCNTs as a biodegradable, reuseable, and scalable materials for safe seed protection and storage in sustainable agriculture.