Structural characterization and protein interaction profiling of sugarcane bagasse-derived cellulose nanocrystals

Conversion of agricultural waste into high-value biomaterials offers a sustainable solution for mitigating both biomedical and environmental challenges. This paper describes the extraction of cellulose nanocrystals (CNCs) using sugarcane bagasse, a lignocellulosic agro-industrial byproduct, as the raw material, by hydrolysing it in sulfuric acid after chemical pretreatment. The effective elimination of non-cellulose components was confirmed by Fourier-transform infrared spectroscopy (FTIR), whereas the crystal structure of cellulose was revealed by X-ray diffraction (XRD). The crystallinity index was determined to be 67.76% from XRD and 63.3% from ¹³C NMR, indicating a significant proportion of ordered cellulose domains. The existence of rod- and flake-like nanostructures was indicated by morphological characterisation through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The CNC yield was calculated as 12.5%, and the zeta potential value of -42.41 mV indicates good colloidal stability. Molecular docking simulations against five human proteins were performed using cellobiose, a disaccharide representing the repeating structural unit of cellulose, to explore potential molecular interaction behaviour. Cellobiose exhibited relatively higher binding affinity with human salivary amylase (-7.3 kcal/mol) and moderate interaction with lactoferrin (-5.91 kcal/mol), whereas weaker interactions were observed with estrogen receptor alpha, haemoglobin, and VEGF. The interactions are primarily governed by hydrogen bonding and polar interactions. The results of docking provide preliminary molecular understanding of potential interaction with cellulose structural motifs.