Preparation and Characterization of All-biomass Histidine/Regenerated Cellulose Composite Nanospheres

Abstract

The unique imidazole group of histidine endows materials containing it with pH responsiveness, metal-coordination capability, and π–π stacking interactions. However, the development of fully bio-based nanostructured supports that enable efficient histidine immobilization while maintaining abundant accessible surface functional groups remains largely unexplored. In this study, regenerated cellulose nanospheres (RCNs) with an average particle size of 88.8 ± 2.1 nm were prepared through a dissolution–regeneration process and subsequently oxidized to introduce reactive aldehyde groups. Histidine was then covalently grafted onto the RCN surface via a Schiff base reaction, yielding fully bio-based histidine/regenerated cellulose composite nanospheres (His-RCNs) with an average particle size of 39.3 ± 1.1 nm. The reduced particle size after grafting is expected to provide greater accessible surface area for interfacial interactions and subsequent functionalization. Morphological, structural, and thermal analyses confirmed the successful grafting of histidine while preserving the regenerated cellulose framework and spherical morphology. Quantitative analysis revealed that regenerated cellulose and grafted histidine accounted for 79.2 wt% and 20.8 wt% of the final product, respectively. By integrating the renewable regenerated cellulose nanosphere platform with multifunctional imidazole groups, this work provides a fully bio-based strategy for constructing histidine-functionalized cellulose nanomaterials.