Sustainable Carboxymethyl Cellulose-Based Foams via Deep Eutectic Solvent Processing for pH-Responsive Drug Delivery

Carboxymethyl cellulose (CMC)-based materials are widely studied for functional materials and porous platform applications, yet their stability usually requires energy-intensive thermal curing or toxic chemical crosslinkers, which limit process sustainability. In this work, we present a more sustainable approach for the preparation of CMC-based foams using deep eutectic solvents (DES) as multifunctional structuring agents. CMC hydrogels were prepared with different DES at room temperature, followed by freeze-drying to obtain foams. Among the tested DES, choline chloride:oxalic acid (1:1) combined with glycerol produced foams with the most favorable properties, including high water uptake (288.24 ± 3.02% after 1 h) and water stability for 28 days. Morphological analysis revealed a homogeneous and interconnected porous network (32.2 ± 13.3 µm), while compression tests demonstrated good mechanical recovery (93.29 ± 3.12% over 10 cycles). Fourier transform infrared spectroscopy suggests interactions between CMC and DES, especially hydrogen bonds. The foams exhibited pH-dependent behavior, with limited resveratrol release under acidic conditions (22.2 ± 4.0% after 24 h), with significant release at pH 7.4 (85.30 ± 5.75%) and total release at pH 13.0. Drug release kinetics suggest a diffusion-controlled mechanism under acidic pH, transitioning to anomalous transport at higher pH values. This study demonstrates that DES can be used to prepare CMC-based foams, providing a more sustainable route to porous materials. Although biological validation is needed to confirm therapeutic safety, this study provides an initial physicochemical basis for using these matrices as tunable and stimuli-responsive porous materials.