• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.453-458
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• 2009

Recently, new methods to synthesize and process polymers without toxic organic solvents are needed in order to solve environmental problems. The use of supercritical carbon dioxide as a solvent for the polymer synthesis is attractive since it is non-toxic, non-flammable, naturally abundant, and the product may be easily separated from the solvent. In this study, we developed the method using super critical $CO_2$ to prepare P(MAA-co-EGMA) hydrogel nanoparticles as an intelligent drug delivery carrier. The effects of concentrations of PtBuMA-PEO as a dispersion stabilizer and AIBN as an initiator on the particle synthesis were investigated. When PtBuMA-PEO concentration increased, the particle size decreased. However, there was no significant difference in the particle size according to the AIBN concentration. There was a drastic change of the equilibrium weight swelling ratio of P(MAA-co-EGMA) hydrogel nanoparticles at a pH of around 5, which is the $pK_a$ of PMAA. At a pH below 5, the hydrogels were in a relatively collapsed state but at a pH higher than 5, the hydrogels swelled to a high degree. In release experiments using Rh-B as a model solute, the P(MAA-co-EGMA) hydrogel nanoparticles showed a pH-sensitive release behavior. At low pH(pH 4.0) a small amount of Rh-B was released while at high pH(pH 6.0) a relatively large amount of Rh-B was released from the hydrogels.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.106-110
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• 2006

If drugs are made from nanoparticles, their formulations can be more effective than the conventional ones. Especially, water insoluble drugs having low absorption rates into our body could show improvement in their adsorption and bioavailability by decreasing their particle sizes to nanometers. In this study, polyvinylpyrrolidone (PVP) and various sugars were employed as stabilizers for the nanoparticles of a water insoluble drug, Itraconazole. Nanoparticles were successfully produced by the wet slurry process for five days. Then, spray drying converted the aqueous dispersions into dry powders, and the redispersibility of dried nanoparticles into water was investigated. The effects of temperature, pressure, and flow rate were studied to understand the importance of processing variables on redispersibility. It was found in particle size analysis that nanoparticles containing sugars have better redispersibility than those without sugars. Additionally, the mainly spherical morphology of dried nanoparticles was identified by SEM (Scanning Electron Microscopy) and AFM (Atomic Force Microscopy).