Encapsulation and delivery of curcumin in cellulose nanocrystals nanoparticles using pH-driven method

The purpose of the work was to explore the possibility of encapsulation and delivery of curcumin using cellulose nanocrystals (CNC) as a single wall material by the pH-driven method to solve the curcumin challenges of instability, low water solubility, and poor bioaccessibility. Curcumin-loaded CNC nanoparticles (CNC/Cur) were produced, showing the particle size of less than 100 nm, polydispersity index of less than 0.3, and high negative zeta-potential. CNC/Cur exhibited a high encapsulation efficiency of more than 90% even at the lowest mass proportion of CNC-to-Cur of 1:5. Compared with other reported carriers carrying curcumin, the high loading capacity was a highlight of CNC/Cur. CNC/Cur with the mass proportion of CNC-to-Cur of 1:1 exhibited the lowest particle size, presenting sphere, which is accompanied by free CNC between CNC/Cur. The formation of CNC/Cur was mainly driven by hydrophobic interaction, followed by hydrogen bonding, and it converted the crystal forms of both curcumin and CNC into amorphous. It could be stable at pH 3.0-8.0, which is attributed to its strong electrostatic repulsions. And it exhibited stability during storage at 25 degrees C for four weeks and effectively slowed the degradation of curcumin. Additionally, the bioaccessibility of curcumin was improved by CNC/Cur.