IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 BOOK OF ABSTRACTS 80 Research Frontiers Tuesday, 25 August 2026 / Hall B+C SL34 From Trash to Treasure: Humic-Based Nanocarriers and Hydrogels for Sustainable Agriculture and Wastewater Treatment Davide Savy1, Gennaro Volpe2, Antonio De Martino1, Sara Nastasi2, Bianca Maria Orlando Marchesano2, Ilaria Di Lelio1, Mariamelia Stanzione3, Maria Cristina Bonza2, Fancesco Pennacchio1, Maria Antonietta Rao1 1 Department of Agriculture, University of Naples, Piazzale Carlo di Borbone I, 80055 Portici (IT) – email address: davide.savy@unina.it 2 Department of Biosciences, University of Milan (IT) 3 Institute of Polymers, Composites and Biomaterials-CNR (IT) Humic Substances (HS) are well known for their plant biostimulant properties, as widely indicated in literature [1]. However, due to their high molecular heterogeneity, novel uses can be imagined for these complex materials, such as in the production of nanocarriers (NCs) and hydrogels (Hyg). In this work, we exploited the electron-donating capacity of HS in order to crosslink chitosan chains and synthesise spherical nanoparticles via the so-called ionotropic gelation [2]. Such nanoproducts were also used to encapsulate and deliver double-stranded RNA molecules (dsRNA) able to silence specific a gene of Spodoptera littoralis. The efficacy of such biopesticide, indeed, relies on the reduction of gene expression upon dsRNA application, a well-studied RNA interference mechanism [3]. Our nanocarriers entrapped > 90% of the dsRNA thanks to the significant non-covalent interactions with HS alkyl and aromatic moieties, as well as with the positively charged amino groups in chitosan, and were shown to protect it from pH-mediated degradation. Also, once inside the insect gut, the NCs released the dsRNA, which was still functional, thereby efficiently silencing the targeted gene. Moreover, in order to study the fate of the synthesized NCs within plant leaves, we encapsulated a fluorophore (fluorescein isothiocyanateFITC), and sprayed the nanosuspension on tomato leaves. Our results suggested that not only NCs are able to penetrate plant cuticle, but that they localize in the epidermis at the apoplast level in a stable manner for 96 h. Another technologically advanced use of Humic Substances is related to their ability to modulate the physicalchemical properties of alginate beads. Indeed, sodium alginate may form Hyg when dripped into a solution of calcium chloride. Here, calcium ions replace sodium ions in the alginate polymer chains, linking them together, ultimately forming a stable hydrogel. Interestingly, adding HS was shown to significantly alter the structure and reactivity of Hyg beads, therefore offering a convenient
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