Biomedical subjects

Jin-Chul Kim

Publications and source records attributed to Jin-Chul Kim.

7 recordsLinked to original sources

PubMed2006

Preparation and characterization of chitosan/gelatin microcapsules containing triclosan.

Chitosan/gelatin (C/G) microcapsules containing triclosan were prepared by a spray drying method. The core material, triclosan (TS) dissolved in octyl salicylate (OS), were emulsified in an aqueous solution containing variable ratios of chitosan/gelatin. The microcapsules were obtained by spray-drying the emulsions. On the scanning electron micrographs, the microcapsules were spherical and exhibited a core and shell morphology. The thermograms of the microcapsules showed no evidence for the melting of TS, suggesting that TS remained dissolved in the cores of the microcapsules and did not exist as a solid crystalline even after dry microcapsules were formed. According to the results of microelectrophoresis study, the point of zero charge of the microcapsules occurred around pH 9.0 and a higher content of chitosan in the microcapsule wall resulted in a higher positive charge of zeta potential. The degree of release of TS and OS from the C/G microcapsules in an aqueous solution of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was investigated. When chitosan is included in the wall of microcapsules, the degree of release was suppressed. This indicates that chitosan forms a more compact wall than gelatin. On the other hand, TS was released much more than OS. The preferred release of TS is probably due to the higher solubility of TS in the HP-beta-CD solution.

Calorimetry, Differential Scanning↗

PubMed2005

Release property of temperature-sensitive alginate beads containing poly(N-isopropylacrylamide).

The graft copolymer (APN) of alginate and poly(N-isopropylacrylamide) (PNIPAM) were synthesized and APN beads were prepared by dropping the aqueous solution of the copolymer into an aqueous solution of Ca(2+) solution. Alginate chains were employed to play a role in forming beads by electrostatic interactions with a multivalent ion, Ca(2+). Grafted PNIPAM segments were adopted to act as a valve for the pores of the beads, since they exhibit the properties of thermal contraction and expansion. The percent of release of blue dextran from APN beads was higher at 40 degrees C than at 25 degrees C. The difference in the release between two temperatures became more distinguishable when the content of PNIPAM in APN beads is higher. Below lower critical solution temperature (LCST), the expanded PNIPAM would close the pores of the beads, resulting in a lower release rate. Above LCST, the thermally contracted polymer would open the pores, resulting in a higher release rate. The percent of release from APN beads were investigated when the temperature of the release medium is altered. The release rate was relatively low at 25 degrees C. The temperature, however, changed up to 40 degrees C, a marked increase in the release rate was observed. These trends were found to be reproducible when the temperature was repeatedly altered between 25 and 40 degrees C. As a result, a stepwise response to the temperature alteration was obtained.

Acrylic Resins↗

PubMed2004

Monoolein cubic phases containing hydrogen peroxide.

Monoolein (MO) cubic phases were prepared by hydrating MO using distilled water or 12wt.% H(2)O(2) solution so that the content of aqueous phase in the cubic phase is 30wt.%. The thermal transition of the isotropic cubic phase to reversed hexagonal phase was observed on a polarizing photomicroscope and the transition temperature was found to be around 65 degrees C on a differential scanning calorimeter (DSC). Small-angle X-ray scattering (SAXS) patterns indicated the cubic phases had diamond surfaces. The cubic phase released H(2)O(2) into an aqueous phase in a saturation manner so that approx. 50% of total loaded H(2)O(2) release in the first 10 h and thereafter relatively slow was observed over 40 h. The cubic phase was stable at 45 degrees C for 56 days before it broke down into an oily phase and an aqueous phase in 70 days. According to (1)H NMR spectrum, glycerol moiety and -CH(2)=CH(2)- of the oily phase were detected less in number than those of intact MO. Therefore, the hydrolysis and the oxidation of MO would be responsible for the breakdown of the cubic phase. The tensile adhesive forces of the cubic phases were higher than a skin-adhesive patch prepared using polyacrylate. The cubic phase containing H(2)O(2) could be used as a topical disinfected gel for a wounded skin.

Calorimetry, Differential Scanning↗

PubMed2004

Two-dimensional packing patterns of amino acid surfactant and higher alcohols in an aqueous phase and their associated packing parameters.

An amino acid surfactant, monosodium N-stearoyl-L-glutamate (MSSG), was assumed to associate with higher alcohols (HAs) in 1:1 molar ratio in an aqueous phase, and the packing parameters of the 1/1 MSSG/HA associates, Pa, were calculated by molecular dynamics (MD). Pa is defined as At1(l(t1)+l(t2))/a(h)l(t1), where At1 stands for the cross-sectional area of the MSSG tail, l(t1) for the length of the MSSG tail, l(t2) for the length of the HA tail, and a(h) for the area of the MSSG head group. The Pa value increased from 0.83 to 1.02 as the HA tail length (l(t2)) increased from C14 to C22. Associates of HAs having longer tails with MSSG are likely to fit better into bilayers because Pa is closer to 1 when l(t2) is longer. In the graphical results of the MD simulation for the association, however, a steric hindrance was found between the head groups of MSSG/HA when l(t2) was > or = C19. Based on this result, HA was classified into short-chain HA (SCHA, l(t2) < C19) and long-chain HA (LCHA, l(t2) > or = C19), and several possible packing units, composed of compositional combinations of MSSG, SCHA, and LCHA, were proposed. The packing unit is a building block which could constitute bilayers, and it is composed of variable compositional combinations of MSSG/HA. Assuming that SCHA associates with MSSG, the packing parameter, Punit, was calculated in a water box by MD for each packing unit. Punit is the packing parameter of a packing unit and it is defined as Vu/l(u)a(u), where Vu is the tail volume of the packing unit, l(u) is the chain length, and a(u) is the head area. For the calculation, stearyl alcohol (C18-OH, SA) was chosen as a SCHA and behenyl alcohol (C22-OH, BA) as a LCHA. When the compositional ratio MSSG:SCHA:LCHA was 1:1:1, Punit was around 1. The packing unit having Punit of around 1 formed a colloidally stable suspension for 30 days and its aggregate was a lamellar structure. However, the other packing units, for which Punit deviates significantly from 1, precipitated out in their suspensions and showed no evidence of a lamellar structure. According to the graphical MD simulations for the compositional MSSG/SCHA/LCHA associations in bilayers, vertical steric hindrance was found between LCHAs when Punit deviated significantly from 1. The steric hindrance would prevent the packing units from forming a stable bilayer and induce precipitation in the suspensions. Therefore, a proper combinational ratio of MSSG:LCHA:SCHA would play a major role in forming a lamellar structure.

Alcohols↗

PubMed2003

Preparation of liposomes with glucose binding sites: liposomes containing di-branched amino acid derivatives.

Di-branched amino acid derivatives, such as dihexadecyl-glutamate-glutamine (DHD-glu-gln), dihexadecyl-glutamate-asparagine (DHD-glu-asn) and dihexadecyl-glutamate-glutamic acid (DHD-glu-glu), were synthesized, and then incorporated into lipid vesicles (liposomes) using dipalmitoylphosphatidylcholine (DPPC). To form binding sites toward glucose, the liposomes containing amino acid derivatives were mixed with glucose above the phase transition temperature (PTT) of DPPC and subsequently the temperature was lowered below the PTT. The glucose-binding affinity of liposomes containing amino acid derivative with or without glucose imprinting was evaluated by surface plasmon resonance (SPR) and equilibrium dialysis technique. SPR of liposomes containing each amino acid derivative or three amino acid derivatives revealed that only the liposomes containing all three amino acid derivatives had glucose-binding affinity and that the glucose-imprinting process was essential to fix the amino acid derivatives into a glucose binding site on the liposomes. Equilibrium dialysis studies of glucose-imprinted liposomes produced curvilinear Scatchard plots, indicating that the amino acid derivatives play a role in glucose binding. Di-branched amino acid derivatives synthesized in this study are promising agent for the development of biocompatible synthetic glucose binding materials.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2002

Preparation of microspheres by an emulsification-complexation method.

Microspheres were prepared by complexation of a cationic polymer, polyquaternium-24, and an anionic surfactant, sodium lauryl sulfate (SLS). The cationic polymer solution was emulsified in dimethylsiloxane to give water in silicone emulsion (W/Si), and it was used as a template for the formation of microspheres. The emulsion was dispersed into the SLS solution. In this process, two kinds of droplets, silicone dropletes and microspheres composed of the cationic polymer and SLS, were formed, evidenced by X-ray energy dispersive spectra. The mean diameter of the microspheres was reduced from 105.7 to 64.8 mum as the stirring rate for W/Si preparation increased from 300 to 1000 rpm. It is believed that water droplets in W/Si emulsion, when exposed to SLS solution, could be solidified by the complexation of the cationic polymer and the anionic surfactant.

Dimethylpolysiloxanes↗

PubMedDate not supplied

Minoxidil-containing dosage forms: skin retention and after-rinsing hair-growth promotion.

Three kinds of topical dosage forms of minoxidil (MXD), namely vesicles, double emulsions, and an inclusion complex with hydoxypropyl-beta-cyclodextrin (HP-beta-CD), were prepared. The skin retention of MXD in the preparations was evaluated in vitro using hairless mouse skins. After applying the preparations onto the skin and rinsing it, the amount of the drug left on the skin was determined using HPLC. Retention was the highest when the drug was encapsulated in cationic vesicles. Nonionic vehicle, the double emulsion, and HP-beta-CD left no significant amount of the drug after rinsing the skin. Thus, an ionic interaction between the cationic vehicle and negatively charged skin is likely responsible for the relatively high skin retention. In vivo hair growth-promotion effect of each dosage form was investigated, in which the sample application onto the clipped backs of female mice (C57BL6) and the subsequent rinsing of the backs were done once a day for 30 days. Only MXD in the cationic vesicles had hair growth promotion effect, possibly due to significant skin retention.

2-Hydroxypropyl-beta-cyclodextrin↗