Nano-cellulose 3D-networks as controlled-release drug carriers.

Bacterial cellulose (BC) membranes are used as the carrier for berberine hydrochloride and berberine sulphate to produce a new controlled release system. Release studies and transdermal experiments were carried out in vitro. Carrier BC can significantly extend the drug release time, in contrast to existing commercial carriers. Freeze-dried BC membranes 10 mm thick were optimized for drug delivery. The lowest release rate was in simulated gastric fluid (SGF) or in H2SO4 solution, the highest in simulated intestinal fluid (SIF) and an intermediate rate was found in alkaline conditions. The release curves closely followed the Ritger-Peppas model with free diffusion the most prominent mechanism. Scanning electron microscopy (SEM) analysis demonstrated that BC fibers were swollen in acid and base conditions. 1H high-resolution magic angle spinning nuclear magnetic resonance (1H HRMAS NMR) diffusion-ordered spectroscopy (DOSY) analysis showed that there was an interaction between the drugs and BC. The structure of BC, the media and the solubility of the drug all influenced the sustained-release behavior. The results from the release studies, the electron micrographs, and the transdermal experiments were in good agreement.