Cellulose Nan ocrystal H ydrogel s as N ovel D elivery S ystem s for a C ationic D rug – temperature dependent behavio u r and drug release

Abstract

Cellulose nanocrystals (CNC) hydrogel is a promising formulation in drug delivery domain. Its natural origin, cytocompatibility, biodegradability, and low cost as well as its unique physical characteristics makes it a promising drug delivery system (DDS). Aim: This study evaluated CNC hydrogel and its potential as a DDS for chlorhexidine (CHX) as a cationic drug model. Methodology: The hydrogels were prepared in three concentrations 5%, 10%, and 20% CNC in unionized water. CHX was added to each hydrogel in two different concentrations (0.01 mg/ml and 0.02 mg/ml). All concentrations were characterized mechanically to investigate the viscoelastic properties of each concentration. This was done by performing oscillating stress, frequency and temperature sweeps by a controlled stress rheometer. Also, in vitro drug release was assessed by dialysis release method. Results: The stability and strength of the CNC hydrogels found to be directly proportional to the concentration of CNCs in the hydrogel. The 5% CNC hydrogel was thermoresponsive hydrogel, where its elastic modulus (G’) increases with temperature rising from 25°C to 37°C. Adding CHX to the low-density (low CNC concentration) hydrogels decreases the elasticity of the gel. 5% CNC hydrogel in 2500:1 and 5000:1 CHX ratios lost their viscoelastic properties in both 25°C and 37°C temperatures. However, in 10% CNC hydrogels, the viscoelastic properties of the hydrogel were slightly enhanced with CHX loading. CNC hydrogels found to be controlling the drug release of CHX at 37°C. The controlled drug release is CNC concentration dependent which means, the higher the density of the polymer the more controlled the drug release.