Study On Polymer Coating Of Astaxanthin Via The Supercritical Fluid Precipitation Technique

It is a new technique to encapsulate non-water-soluble drugs by using biocompatible or bioactive polymers in recent years which can improve absorption, bioavailability, photostability, oxygen resistance and the thermostability of those non-water-soluble drugs. Solution Enhanced Dispersion by Supercritical Fluids(SEDS) process has become a new method to prepare coated microparticles for its unique advantages. The study on coating of crude astaxanthin with polymer matrix can improve the characteristics of astaxanthin and enhance its added value, which is significant to utilize astaxanthin.In this dissertation, Haematococcus pluvialis produced in Hawaii was chosen as raw material. Astaxanthin was obtained by organic solvent leaching, column chromatography and recrystalization. With the SEDS process, astaxanthin/polymer microparticles which were analyzed by using scanning electron microscopy (SEM) and X-ray diffraction were obtained by using dichloromethane as solvent, PVP-K 90 as polymer carrier.The results show that particle sizes of microparticles first decrease and then increase with the increasing of pressure. The morphology changed from irregular shape of leaf to regular shape of leaf, strip and leaf, coated yield increase at first and then decrease. There was no obvious difference on particle size with the increasing of temperature, and microparticle change from regular strip to irregular shape of leaf, coated yield increase rapidly and then decrease sharply. Particle size and coated yield increase first and then decrease with the increasing of astaxanthin content in initial solute, morphology transform from short lozenge to long strip. With the increasing of solution concentration, there is no significance change except for agglomeration. When the PVP-K 90, PVP-K 30, PEG 8000 was used as polymer carrier, it can be seen that astaxanthin was equably distributed on polymer, but the surface of particles was harshly, oilily and oilily, respectively. The strip microparticles with toothed side were obtained and presented astaxanthin distributing equably on L-PLA. The results showed that the coated ratio was the highest when PEG 8000 was used as encapsulated materials.