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This study focused on surface modification of cellulose nanocrystals (CNCs) to create a biocompatible, stable, and hydrophilic substrate suitable for use as a coating agent to develop a dual-contrast composite material. The CNCs were prepared using acid hydrolysis. Hydrolysis was completed using 64% sulfuric acid at 45 °C for 1 h, which was combined with polyethylene glycol and sodium hydroxide (PEG/NaOH). The yield of samples exhibited prominent physicochemical properties. Zeta (ζ) potential analysis showed that the CNCs sample had excellent colloidal stability with a highly negative surface charge. Transmission electron microscopy (TEM) analysis confirmed that the CNCs sample had a rod-like morphology. On the other hand, field-emission scanning electron microscopy (FESEM) analysis showed that the acid hydrolysis process caused a significant reduction in particle size and changed surface morphology. In addition, cellulose nanocrystals with polyethylene glycol and sodium hydroxide (CNCs-PEG/NaOH) have many noteworthy properties such as colloidal stability, small hydrodynamic size, and water dispersibility. Furthermore, the MTT assay test on Hep G2 cells demonstrated good biocompatibility of the CNCs-PEG/NaOH and did not exhibit any cytotoxic effects. Hence, CNCs-PEG/NaOH holds the potential to serve as a dual-contrast agent for MRI techniques and other biomedical applications.

This paper documented the synthesis of cellulose nanocrystalline (CNCs) extracted from commercially-sourced microcrystalline cellulose (MCC) via acid hydrolysis and the subsequent characterization analyses of the yield. The hydrolysis process was completed using 64% sulphuric acid at 45°C for 1 hour. The yield exhibited prominent physicochemical properties. The X-ray diffraction (XRD) analysis suggested that the crystallinity degree of the CNCs was 8.94% higher than MCC sample. Meanwhile, zeta potential (ζ) analysis showed that the CNCs sample possesses highly negative surface charges of 25.6±8.24 mV. Further investigation by transmission electron microscopy (TEM) analysis revealed the rod-like morphology of the CNCs sample with average diameter of 9.36±3.81nm and 83.84% crystallinity index. Whereas, via field emission scanning electron microscopy (SEM) analysis confirmed considerable reduction in particle size and changes in surface morphology post-acid hydrolysis of the CNCs, with diameter of 7.65±2.56 nm. It is envisaged that the acid hydrolysis technique is promising in synthesizing CNCs of high crystallinity with smaller size for various possible applications, potentially as a contrast agent.