Preparation And Characteration Of Biodegradable Drug Delivery Systems Encapsulating Berberine Hydrochloride

The present work used starch, alginate and carboxymethyl chitosan (CMC) to prepare starch/alginate interpenetrating polymer network (IPN) microspheres and alginate microsphere/ CMC hydrogel drug delivery system (DDS). Modified emulsification/gelation method was used to prepare blend microspheres. Microscopy and SEM were used to observe the morphology. The microspheres kept spherical and well dispersed in water. The microspheres can basically keep spherical with little deformation after freeze-drying which could be observed by SEM. The size distribution was mainly affected by preparation conditions especially stirring speed and O/W ratio. Increasing stirring speed and decreasing O/W ratio would cause a decrease in size and uniform size distribution. We found that 2:1 was a proper W/O ratio. Polymer concentration also affected size and size distribution. FTIR proved that the two polymers were well mixed. We took berberine hydrochloride as a model drug to be encapsulated by the blend microspheres. Highest encapsulation efficiency of more than 80% was achieved by using proper conditions. Confocal laser scanning microscopy(CLSM) was used to observe the drug distribution in microspheres. Drug distribution was uniform. Drug release performance was studied in both pH 7.4 phosphate buffer solution(PBS) and pH 1.2 hydrochloride acid solution (HAS)at 37±0.5℃and 50 r/mmin.The drug concentration was determined by UV at 345 nm. It was found that release in PBS was fast and a considerable burst release happened. On the contrary, a delayed release was noted in HAS. The release data were fitted with several classic models. It was found that a first-order model fitted best. In order to get more delayed release and decrease burst release, new DDS of alginate microsphere/CMC hydrogel was prepared. The surface morphology was observes with metallographic microscope and SEM. Microspheres could be seen to be distributed in hydrogel. More microspheres could be seen in DDS with more microspheres added. Mechanical test proved that DDS had better compressive strength than pure hydrogel. But increase of microspheres would cause a little decrease of compressive strength. Release performance was studied in pH1.2 HAS,pH7.4 PBS and pH6.3 saline solution. More delayed release was found compared to pure microspheres.