Cellulose-Based Photothermal Coating: A Sustainable Solution for Seed Protection and Long-Term Grain Storage

High-output modern agriculture based on synthetic chemicals (biocides, pesticides, and fertilizers) feeds the growing global population. To completely abandon the use of pesticides and fertilizers will undoubtedly cause a severe food crisis worldwide, and sustainable alternative solutions are urgently demanded to stop biocides and fertilizers overuse. Herein, a versatile and green strategy is proposed for seed protection and long-term storage of grains using a cellulose-based photothermal coating (PDA NPs@Cell-N⁺) that consists of photothermal polydopamine nanoparticles (PDA NPs) and a positive-charged cellulose derivative (Cell-N⁺) to eradicate seed-borne bacteria and fungi simply under infrared irradiation. In vitro and in vivo assays and the seedling-stage phenotypes of mung bean (Vigna radiata) suggest that pathogenic microbes, including the tough Aspergillus flavus (inhibition ratio >99%), can be efficiently eliminated by photothermal therapy. Thus, the seed-borne diseases of mung beans can finally be prevented. Owing to excellent solubility and biocompatibility, the PDA NPs@Cell-N⁺ coating can be washed off and recycled without food safety concerns. PDA NPs@Cell-N⁺ can be a nature-based solution for seed protection and long-term grain storage.