Burst-free and sustained release of diclofenac sodium from mesoporous silica/PEI microspheres coated with carboxymethyl cellulose/chitosan layer-by-layer films

Finding novel systems for controlled delivery of drugs is still a stringent need. Fabrication of drug delivery systems (DDS) having a cross-linked low molar mass synthetic polycation such as poly(ethylene imine) (PEI) entrapped into the pores of a mesoporous silica followed by coating the silica/PEI composite microspheres with a pH responsive layer-by-layer (LbL) film is presented for the first time in this work. The LbL film, which behaves as drug release lingering component of the composite, was constructed with carboxymethyl cellulose (CMC) and chitosan (CS) as building blocks. Silica/PEI/(CMC/CS)n composites were fully characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and EDX spectra, and by the nitrogen sorption/desorption isotherms (BET analysis). The dynamic of LbL film construction was followed by potentiometric and polyelectrolytic titrations. Diclofenac sodium (DS) was used as a model drug to demonstrate the potential of the as prepared composite as novel system for controlling the release of drugs. Investigation of the release kinetics evidenced the influence of the LbL film on the mechanism of DS release. Taking into account the values of nr in the Korsmeyer-Peppas equation, pseudo-Fickian release, with nr