Composite Hydrogel Beads Based on Chitosan and Laponite: Preparation, Swelling, and Drug Release Behaviour

Biopolymer/layered silicate composites have shown unique advantages and potentials for the passive targeting of drugs because they can overcome the burst drawbacks of organic carrier, increase the drug utilization and enhance the controllable capability of drug release. Furthermore, the biocompatibility and non- toxicity of biopolymers is retained, and therefore it is promising and applicable in pharmaceutical fields. The main research aim of this work was to develop a series of biopolymer/layered silicate composite beads based on chitosan (CTS) and Laponite (LA) by a simple ionic cross-linking reaction using sodium tripolyphosphate as the cross-linker. The resultant beads were characterized by Fourier transform infrared spectroscopy, scanning electronic microscope and X-ray diffraction analysis. The swelling behaviour in physiological pH solutions (7.4 and 1.2), drug encapsulation effi- ciency and controlled release behaviour were also investigated by using Ofloxacin as the model drug to reveal the effects of introduced LA. The results indicate that the incorporation of LA remarkably improved the swelling behaviour, enhanced the drug entrapment efficiency, and slowed down the drug release behaviour in contrast to the pure organic CTS beads. The exfoliated LA clay could act as a physical cross-linker to facilitate the formation of network structure between the CTS and LA. It is suggested that LA may be developed as an effective additive for fabricating a sustained drug delivery system.