Dong-Woon Kim

Pectin microspheres for oral colon delivery: Preparation using spray drying method andin vitro release of indomethacin

Drug delivery systems that are based on pectin have been studied for colon specific delivery using the specific activity of colon microflora. The aim of this study was to design a novel method of manufacturing pectin microspheres without oils and surfactants and to investigate the potential use of the pectin microsphere as an oral colon-specific drug carrier. The pectin microspheres were successfully formed using the spray drying method and crosslinking with calcium chloride. From the crosslinked pectin microspheres, indomethancin (IND) release was more supressed than its release from non-crosslinked microspheres. In a low pH (pH 1.4) environment, the pectin microspheres released IND at an amount of about 18±2% of the total loaded weight for 24h while the release rate of IND was stimulated at neutral pH (pH 7.4). IND release from the pectin microspheres was increased by the addition of pectinase. The results clearly demonstrate that the pectin microspheres that were prepared by the spray drying and crosslinking methods are potential carriers for colon-specific drug deliveries.

Rosin microparticles as drug carriers: Influence of various solvents on the formation of particles and sustained-release of indomethacin

The aim of this study was to formulate a sustained release system for indomethacin (IND) with rosin gum obtained from a pine tree. Rosin microparticles were prepared by a dispersion and dialysis method without the addition of surfactant. In order to investigate the influence of solvents on the formation of colloidal microparitcles, various solvents like ethanol, DMF, DMAc, and acetone were used. The rosin microparticles containing IND were characterized by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The morphologies of rosin microparticles observed by scanning electron microscopy (SEM) were spherical. The solvents used to dissolve rosin significantly affected the drug content and drug release rate of IND. The release behaviors of IND from the rosin microparticles were dependent on the drug content and size of the particles. Rosin microparticles with a higher drug content and of a larger particle size had a slower drug release rate. Also, the IND release rate from the rosin microparticles could be regulated by the rosin content in the microparticles. From these results, rosin microparticles have the potential of being used as a sustained release system of IND.

Alginate/Carboxymethyl Scleroglucan Hydrogels for Controlled Release of Protein Drugs

Alginate/carboxymethyl scleroglucan (CMSG) hydrogels were suggested as a novel carrier for the controlled release of protein drugs. The drug release characteristics of alginate hydrogels were improved by CMSG addition. Scleroglucan (Sclg) was carboxymethylated using monochloroacetic acid in aqueous alkaline medium. Alginate/CMSG hydrogels were prepared by dropping the mixture solution of alginate/CMSG into calcium chloride solution. The swelling behaviors and drug release characteristics of the hydrogels were investigated in the buffers of pH 1.2 or 7.4. As the CMSG content increased in the hydrogels, the swelling ratio of the alginate/CMSG hydrogel increased rapidly in the buffer of pH 7.4. At pH 1.2, however, the swelling ratio significantly decreased compared to that at pH 7.4. According to in vitro release tests, only 15% of ovalbumin, investigated as a model protein drug, was released from the alginate/CMSG hydrogels at pH 1.2 within 6 h. At pH 7.4, however, the drug release significantly increased due to the rapid swelling of the hydrogels. The release and swelling behaviors of the hydrogels could be controlled by changing the CMSG content in the hydrogels. These results supported the use of alginate/CMSG hydrogels as a suitable carrier for the controlled release of protein drugs in a pH responsive manner.

Influence of histidine on the release of all-trans retinoic acid from self-assembled glycol chitosan nanoparticles

Objective: In this study, the influence of N-acetyl histidine (NAHis) on the all-trans retinoic acid (ATRA) release from the NAHis-conjugated self-assembled glycol chitosan (GC) nanoparticles was investigated. Methods: NAHis was conjugated to GC as a hydrophobic moiety to prepare the self-assembled nanoparticles, and ATRA was incorporated into the inner core of the NAHis–GC nanoparticles. The ATRA release from NAHis–GC nanoparticles was performed at 37°C in a phosphate-buffered saline buffer (pH 5.5 or 7.4) for 48 hours. Results: At a pH of 5.5, less than 20% (w/w) of total loading amount of ATRA was released from the nanoparticles after 48 hours. In contrast, two times greater amount of ATRA was released at a pH of 7.4. The ATRA release rate from the NAHis–GC nanoparticles was significantly slower at a pH of 5.5 than at a pH of 7.4. Conclusion: The release profiles of ATRA that was incorporated into the NAHis–GC nanoparticles were controlled by the NAHis content in the GC nanoparticles.

Improved suspension stability of calcium carbonate nanoparticles by surface modification with oleic acid and phospholipid

We prepared and characterized calcium carbonate nanoparticles (CC NPs) that were surface-modified with oleic acid (OA) and phosphatidylcholine (PC) in order to improve their suspension stability in an aqueous solution. The improvement in the suspension stability of CC NPs in an aqueous solution may be helpful to extend their applicability to a wider range of biological applications. The CC NPs were coated with OA by making use of their electrostatic potential and were then decorated with PC. The CC NPs surface-modified with OA and PC were successfully constructed, and the existence of the decorated OA and PC in the surface of the PC-OA-CC NPs was observed via transmission electron microscopy (TEM) and was confirmed by thermo gravimetric analysis (TGA), Xray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) analyses. The PC-OA-CC NPs floating in an aqueous solution exhibited better stability when compared to non-surface-modified CC NPs. The DLS and TEM results revealed that the degree of size agglomeration for the CC NPs was significantly reduced by the surface modification with OA and PC. The PC-OA-CC NPs showed a very low cytotoxicity at a high concentration in terms of the cell viability of the RAW264.7 cells. Consequentially, the stability in suspension of the CC NPs in an aqueous solution could be effectively improved through surface-modification with OA and PC. PC-OACC NPs could be useful in increasing the range biological applications for CC NPs.