Stereocomplex poly(lactic acid) nanocoated chitosan microparticles for the sustained release of hydrophilic drugs

In this work, novel chitosan based microparticles were developed by the layer-by-layer deposition of poly(lactic acid) stereocomplex films on their surface in the view of controlling the release of encapsulated hydrophilic drugs. As first step, the quartz crystal microbalance technique was used to monitor the step-by-step deposition of the stereocomplex layers onto chitosan by evaluating the deposited mass for each layer. Chitosan microparticles, with a size ranging between 40 and 90 μm, were then produced by an aerodynamically-assisted jetting technique and covered by a poly(lactic acid) stereocomplex shell. Infrared spectroscopy, wide X-ray diffraction, field emission scanning electron microscopy and contact angle measurements were used to verify the effective poly(lactic acid) adsorption onto chitosan microparticles and the stereocomplex formation. Finally, the release of a hydrophilic local anesthetic, procaine hydrochloride, from uncoated and stereocomplex-nanocoated microparticles was preliminary evaluated over a period of 15 days.