Preparation of pH-sensitive Fe3O4@C/carboxymethyl cellulose/chitosan composite beads for diclofenac sodium delivery.

In this study, we prepared pH- and magnetism-responsive Fe3O4@C/carboxymethyl cellulose (CMC)/chitosan composite microbeads for controlled release of diclofenac sodium (DS) to (i) prevent complete drug release in gastric area, (ii) maintain blood drug concentration in a specific part of the body, (iii) reduce drug administration time and systemic drug toxicity, and (iv) improve drug efficacy. Through one-step solvent thermal treatment, a polyethylene glycol layer was wrapped into Fe3O4 nanoparticles. Then, Fe3O4@C nanoparticles were incorporated into CMC matrix and coated with chitosan layer via a self-assembly technique to form core-shell polyelectrolyte complexes (PECs). The composite beads were characterized by SEM, TEM, FT-IR spectrometry, and TGA. In addition, the effect of different concentrations of Fe3O4@C, CMC, aluminum chloride (AlCl3), and chitosan on the swelling process of composite beads, DS loading, and controlled release behavior was systematically studied. DS encapsulation efficiency in Fe3O4@C/CMC/chitosan beads reached 70.8 ± 0.65% at concentrations of 0.1% Fe3O4@C, 3% CMC, 3% AlCl3, and 1% chitosan. The beads showed a higher swelling index in phosphate buffer at pH 7.4 and 6.8 than at pH 1.2. The composite beads revealed excellent pH-sensitive in vitro drug release profiles and prevented burst release in the gastrointestinal tract.