Carbodiimide coupling versus click chemistry for nanoparticle surface functionalization: A comparative study for the encapsulation of sodium cholate by cellulose nanocrystals modified with β-cyclodextrin

Abstract

Grafting beta-cyclodextrin (β-CD) onto cellulose nanocrystals (CNC) with the formation of well-dispersed nanoparticles (CNC-CD) and understanding their physicochemical properties are appealing but still challenging in controlled-release applications. Two immobilization methods were proposed and examined in this study; (i) copper (I) catalyzed click chemistry (CuACC) and (ii) carbodiimide coupling. Fourier-transform infrared spectroscopy (FTIR), UV–vis, elementary analysis, contact angle measurements, and thermogravimetric analysis (TGA) were conducted to elucidate the surface modifications. Phenolphthalein (PHTH) titration was used to quantify the grafting efficiency of β-CD on the CNC surface. The carbodiimide coupling in dimethyl sulfoxide was effective to introduce the highest amounts of β-CD (0.17 mmol/g sample) to the CNC in this study. The encapsulation process of bile surfactant, sodium cholate (NaC) was investigated by isothermal titration calorimeter (ITC), and the thermodynamic parameters were determined. The “molecular docking” brought by β-CD offers possible new applications of this sustainable nanohybrid system in the environmental, biomedical and pharmaceutical sectors.