Mechanical properties and curcumin release behavior of chitosan hydrogel films reinforced with dialdehyde cellulose nanocrystal

Chitosan hydrogel films are limited by weak mechanical integrity for biomedical drug delivery applications, which often leads to uncontrolled release of hydrophobic compounds such as curcumin. The development of chitosan hydrogels reinforced with dialdehyde cellulose nanocrystal (DACNC) offers a potential strategy to address these limitations. The DACNC hydrogels were developed from oil palm empty fruit bunches (OPEFB) and integrated with curcumin for therapeutic applications. α-Cellulose was extracted through delignification, alkalization, and bleaching, followed by sulfuric acid hydrolysis to yield CNC with a crystallinity index of 82.89%. Subsequent oxidation using sodium metaperiodate (NaIO₄) produced DACNC with 78.67% crystallinity. FTIR confirmed aldehyde functionality by the new absorption at 1731 cm⁻¹. TEM revealed well-dispersed nanocrystalline particles (length 18.65 ± 0.34 nm, diameter 4.85 ± 0.39 nm, and aspect ratio 5.31 ± 0.56), indicating stable crystalline morphology and minimal aggregation after oxidation. SEM micrographs showed smoother and more homogeneous hydrogel surfaces than pristine chitosan. The optimized hydrogel exhibited a swelling (%) of 11,900%, tensile strength up to 9 MPa, elongation at break of 30%. Drug release studies showed that DACNC hydrogels provided significantly more sustained and stable curcumin release reaching 82.19% only at 18 h compared with CNC’s rapid 84.02%. These synergistic enhancements arise from strong interfacial hydrogen bonding between chitosan and DACNC, improving structural integrity and drug retention. The findings highlight DACNC-reinforced chitosan hydrogels as robust, biocompatible platforms for wound healing and controlled drug delivery.