Electrostatic Adsorption and Cytotoxity of Cellulose Nanocrystals with Loading Trace Metal Elements

Cellulose nanocrystal (CNC) is the rod-like nano-object derived from natural cellulose with the features of low toxicity and good biocompatibility, widely used as the functional additive and nanomaterial in the biomedicine. Two negatively charged cellulose nanocrystals, CNC and TO-CNC (surface oxidized CNC), are prepared by the sulfuric acid hydrolysis and further surface oxidization. Based on electrostatic adsorption, five trace metal elements (TMEs) including cobalt (Co), nickel (Ni), manganese (Mn), lead (Pb), and cadmium (Cd) are loaded on the surface of two nanocrystals as the biocompatible nanocarriers. The adsorbed contents of TMEs on two nanocrystals are affected by their surface charge densities and the complexes can keep stability under three varied pH conditions. Two cell lines, viz. human nasopharyngeal cancer cell and normal human bronchial epithelial cell, are selected for the investigation of cytotoxity of these TME-loaded nanocrystals at the concentration range of 0.1-500 µg mL^-1 . The high concentrations of TME-loaded nanocrystals will induce the inhibition of cells activity and proliferation, particularly for Pb²⁺ - and Cd²⁺ -loaded nanocrystals. The cancer cell generally exhibits more sensitivity of cytotoxity to these metal elements than the normal cell, which may be potentially used as the activity inhibitor for specific cells in the future study.