Octylamine-modified cellulose nanofibers-based aerogels to modulate release behavior

Abstract

Cellulose nanofibers (CNF) derived from lignocellulosic biomass are promising materials for sustainable controlled release systems due to their renewability and tunable surface chemistry. However, their intrinsic hydrophilicity limits their interaction with hydrophobic compounds. This study aims to overcome this limitation by introducing amphiphilic character into TEMPO-oxidized CNF via octylamine-mediated amidation, enabling modulation of surface properties and release behavior in aerogel-based delivery systems. CNF obtained from wheat straw biorefinery were successfully functionalized, achieving a degree of modification of ~ 29%, as confirmed by spectroscopic analyses. The formation of amide bonds and incorporation of alkyl chains preserved the crystalline structure while improving thermal stability and reducing surface charge. Both modified and unmodified aerogels exhibited high porosity (> 98%); however, functionalization led to a more refined porous structure with smaller pore size distribution. Hydrophilicity decreased after modification, as indicated by lower swelling capacity and increased contact angle. Release studies were carried out as a functional proof to show the differences in the release behavior, being slower for the hydrophilic molecules (Tetracycline) when the CNF was functionalized, whereas hydrophobic compounds (Curcumin) exhibited markedly different behavior, with faster release from octylamine-modified aerogels, highlighting the role of molecular affinity and matrix interactions. These results demonstrate that octylamine-mediated functionalization is an effective strategy to tailor the surface chemistry and structure of CNF-based aerogels while preserving their integrity. The results highlight the importance of molecular-level interactions in controlling release behavior, particularly for hydrophobic compounds. These findings provide a basis for designing sustainable, bio-based controlled release systems with tunable performance. Moreover, the approach supports the valorization of agricultural residues and offers potential for applications in agrochemical delivery and environmentally responsive technologies.