• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.3928-3932
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• 2011

We synthesized peptide-resin conjugates (1 and 2) by immobilizing ${\beta}$-sheet antibacterial peptide and ${\alpha}$ helical antibacterial peptide on PEG-PS resin, respectively. Conjugate 1 showed considerable antibacterial activity in various conditions, whereas conjugate 2 did not exhibit antibacterial activity. The growths of various bacteria were inhibited by conjugate 1 even at lower concentrations than MIC. Conjugate 1 killed bacteria at MIC and had a potent synergistic effect with current antibacterial agents such as vancomycin and tetracycline, respectively. Overall results indicate that polymer surface modification using antibacterial ${\beta}$ sheet peptide is a powerful way to prevent microbial contamination on polymer surfaces.

• Journal of Pharmaceutical Investigation
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• v.40 no.4
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• pp.219-223
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• 2010

The hyaluronic acid (HA) conjugate bearing $\alpha$-cyclodextrin ($\alpha$-CD) was synthesized as the potential carrier of poly(ethylene glycol) (PEG)-drug conjugates. The HA conjugate was prepared by the reaction between the carboxylic acid of HA and the primary amine of $\alpha$-CD in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and 1-hydroxybenzotriazole. The chemical structure of the conjugate was confirmed using $^1H$ NMR and FT-IR spectroscopy. The conjugate could form nano-sized particles in the presence of PEG by forming the inclusion complexes between $\alpha$-CD at the backbone of HA, which was demonstrated using electrophoretic light scattering and field emission transmission electron microscopy. It is anticipated that this novel kind of nanoparticles can serve as a useful delivery system for PEGylated drugs.

• YAKHAK HOEJI
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• v.48 no.1
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• pp.82-87
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• 2004

Mungbean trypsin inhibitor (MBTI) was isolated and purified from Mung bean which has been used as a galenic and traditional food. MBTI and poly(ethylene glycol) were conjugated by using water soluble carbodiimide. We evaluated the therapeutic value of the MBTI and MBTI-PEG conjugate using animal models, sublethal septic shock model in guinea pig caused by pseudomonal elastase, shock model in rat caused by lipopolysaccharide, and the vascular permeability test by using pseudomonal elastase. In two shock model in guinea p Is and in rat, hypotesion shock was inhibited by pretreatment of MBTI. And also the vascular permeability caused by pseudomonal elastase reduced by pretreatment of MBTI. Also, therapeutic value of the MBTI-PEG conjugate was evaluated by using the sublethal septic shock model caused by pseudomonal elastase. The MBTI-PEG conjugate was more effective than native MBTI against pseudomonal elastase induced septic shock in guinea pig model.

• Macromolecular Research
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• v.14 no.3
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• pp.387-393
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• 2006

Nanoparticles of Poly(L-glutamic acid) (PG) conjugated to the anticancer drug paclitaxel and targeted moiety folic acid (FA) were synthesized and characterized in vitro. The nanoparticles were designed to take advantage of FA targeting to folate receptor (FR) positive cancer cells. The chemical composition of the conjugate was characterized by $^1H-NMR$, FTIR and UV/vis spectroscopy. The selective cytotoxicity of the FA-PG-paclitaxel conjugates was evaluated in FR positive cancer cells. The interaction of the conjugate was visualized by fluorescence microscopy with results confirming the successful preparation of the conjugate and the production of nanoparticles of about 200-300 nm in diameter. The amount of paclitaxel conjugated to FA-PG was 25% by weight. Cellular uptake of the conjugate was FA dependent, and the conjugate uptake was mediated specifically by the folate receptor. These results demonstrate the improved selective toxicity and effective delivery of an anticancer drug into FR bearing cells in vitro.

• Macromolecular Research
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• v.15 no.6
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• pp.547-552
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• 2007

Water soluble polymer, poly(vinyl pyrrolidone) was chosen to conjugate with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(succinyl) (N-succinyl DPPE) to make a new drug delivery system. PVP with an amine group (amino-PVP) was polymerized by free radical polymerization. The amine group of amino-PVP was conjugated with the carboxylic group of N-succinyl DPPE. The resultant conjugate could form nanoparticles in the aqueous solution; these nanoparticles were termed a lipid-polymer system. The critical aggregation concentration was measured with pyrene to give a value of $1{\times}10^{-3}g/L$. The particle size of the lipid-polymer system, as measured by DLS, AFM and TEM, was about 70 nm. Lipophilic component in the inner part of the lipid-polymer system could derive the physical interaction with hydrophobic drugs. Griseofulvin was used as a model drug in this study. The loading efficiency and release profile of the drug were measured by HPLC. The loading efficiency was about 54%. The release behavior was sustained for a prolonged time of 12 days. The proposed lipid-polymer system with biodegradable and biocompatible properties has promising potential as a passive-targeting drug delivery carrier because of its small particle size.

• Journal of Microbiology and Biotechnology
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• v.20 no.10
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• pp.1424-1429
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• 2010

A poly(${\gamma}$-glutamic acid) (${\gamma}$PGA)-cholesterol conjugate was synthesized and its properties were then evaluated. The conjugate exhibited an amphiphilic nature derived from the hydrophilic ${\gamma}$PGA backbone and the hydrophobic cholesterol side chain. The conjugate spontaneously formed nanoparticles, becoming an aqueous solution when at low concentrations, and at high concentrations the result was the formation of a physical gel. By utilizing the self-aggregating properties of the conjugate in water, an artificial chaperone was developed. A complex of protein, with the nanoparticles of the conjugate, was formed and the protein was released upon the dissociation of the nanoparticles through the addition of ${\beta}$-cyclodextrin. For denatured carbonic anhydrase, the activity was recovered in the artificial chaperone of the nanoparticle conjugate.

• Journal of the Optical Society of Korea
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• v.3 no.2
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• pp.47-50
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• 1999

Nonlinear optical properties of an unsaturated polymer (poly trifluroethy dipropargy malonate) are investigated by using a passive Q-switched Nd:YAG laser. Double-peaked structure of phase conjugate signals due to the two-photon-absorption induced thermal effect is clearly is clearly observed and a simple method to remove the thermal effect from the overall phase-conjugate signals is demonstrated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.145-148
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• 2000

In contrast to the $\pi$ -conjugated polymers which typically absorb light only in the visible spectral region, the $\sigma$-conjugated polymers can be used as efficient material absorbing light in the UV region. In this work, the electronic and optical properties of I$_2$-doped $\sigma$ -conjugated poly (methyl-phenylsilylene) (PMPSi) polymer were investigated. DC conductivity up to 1.2$\times$10$^{-4}$ S/cm was obtained by I$_2$-doping. In UV/Vis absorbance spectrum, a new peak was observed near 370 nm, which was explained by polaron model. The photoluminescence (PL) intensity decreased with increasing degree of I$_2$-doping, and the Infrared (IR) spectrum analysis revealed that the dopants are not directly coupled to the polymer, but effect motions of the methyl and phenyl groups.

• 한국전기화학회:학술대회논문집
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• 1999.04a
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• pp.22-22
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• 1999

• Archives of Pharmacal Research
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• v.27 no.8
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• pp.878-883
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• 2004

Tacrolimus (FK506), which is isolated from Streptomyces tsukubaensis, is a new potent immu-nosuppressant. Because of poor solubility in water, the conventional intravenous dosage forms of tacrolimus contain surfactants such as cremophor EL (BASF Wyandotte Co.) or hydroge-nated polyoxy 60 castor oil (HCO-60) which may cause adverse effects. This study relates to a polymer-tacrolimus conjugate, which can be dissolved in water, formed by chemically binding the sparingly soluble drug, tacrolimus, with the water soluble polymer, methoxypoly(ethylene glycol) (mPEG). Water soluble tacrolimus-mPEG conjugates have been synthesized and shown to be function in vitro as prodrugs. These conjugates are in the form of an ester wherein the 24-, 32- or 24,32-positions are esterified. The desired 24-, 32- or 24,32-esterified com-pounds were obtained by initially acylating of tacrolimus with iodoacetic acid at the 24-,32-, or 24,32-positions and then reacting the resulting acylated tacrolimus with a mPEG in the pres-ence of a base such as sodium bicarbonate. These conjugates were converted again into tac-rolimus by the action of enzymes in human liver homogenate, and the half-lives of the conjugates are approximately 10 min in the homogenate, indicating that the esterified tacroli-mus derivatives may be practically applicable as a prod rug for the immunosuppressant.