Exploring freeze-thawed cellulose-based hydrogel from corn Cob: Physicochemical properties, antibacterial activity, and cytotoxicity assay

Abstract

Corn cobs, an abundant yet underutilized agricultural residue in Indonesia, offer a promising source of cellulose for the development of sustainable biomaterials. This study focuses on the extraction of cellulose from corn cobs and its subsequent application in hydrogel fabrication for potential biomedical use. The cellulose was isolated through sequential delignification, bleaching, and acid hydrolysis, yielding a cellulose content of 61.80 %. Hydrogels were synthesized via a freeze–thaw method using varying concentrations of NaOH (2–7 %) to investigate the influence of alkalinity on structural and functional properties. Among all variations, the hydrogel prepared with 3 % NaOH demonstrated the most favorable characteristics, including the highest swelling ratio, enhanced compressive strength, and improved thermal stability. Scanning electron microscopy revealed a uniform, interconnected porous structure, while FTIR spectroscopy confirmed the retention of functional groups associated with cellulose. X-ray diffraction analysis showed a shift from the semi-crystalline nature of the cellulose powder (crystallinity index: 61.48 %) to a predominantly amorphous structure in the hydrogel. Differential scanning calorimetry supported this finding, revealing a significant reduction in heat of fusion. The hydrogel also exhibited antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, while cytotoxicity assays indicated IC₅₀ values above 900 μg/mL, confirming its biocompatibility. These results highlight the potential of corn cob-derived cellulose hydrogels as safe, bio-based materials suitable for biomedical applications, aligning with green bioprocessing and agricultural biotechnology initiatives.