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pH-Induced Micellization of Biodegradable Block Copolymers Containing Sulfamethazine
심우선,이재성,이두성 한국고분자학회 2005 Macromolecular Research Vol.13 No.4
pH-sensitive block copolymers were synthesized by coupling reaction of sulfamethazine and amphiphilic diblock copolymer, and their micellization-demicellization behavior was investigated. Sulfamethazine (SM), a derivative of sulfonamide, was introduced as a pH responsive moiety while methoxy poly(ethylene glycol)-poly(D,L-lactide) (MPEG-PDLLA) and methoxy poly(ethylene glycol)-poly(D,L-lactide-co--caprolactone) (MPEG-PCLA) were used as biodegradable amphiphilic diblock copolymers. After the sulfamethazine was carbox ylated by the reaction with succinic anhydride, the diblock copolymer was conjugated with sulfamethazine by cou pling reaction in the presence of DCC. The critical micelle concentration (CMC) and mean diameter of the micelles were examined at various pH conditions through fluorescence spectroscopy, dynamic light scattering and transmis sion electron microscopy. For MPEG-PDLLA-SM and MPEG-PCLA-SM solutions, the pH-dependent micelliza tion-demicellization was achieved within a narrow pH band, which was not observed in the MPEG-PDLLA and MPEG-PCLA solutions. The micelle showed a spherical morphology and had a very narrow size distribution. This pH-sensitive block copolymer shows potential as a site-targeted drug carrier.
pH & thermo-sensitive biodegradable block copolymers
심우선,이두성 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.1
The synthesis of various diblock (MPEG-PDLLA, MPEG-PCLA) and triblock (PCLA- PEG-PCLA) copolymers was performed through a ring-opening copolymerization of D,L- lactide and - caprolactone with MPEG (monomethoxy poly (ethylene glycol)) and PEG(poly (ethylene glycol)) as an initiator, respectively. The coupling reaction of the block copolymer and carboxylated sulfonamide (SA) as pH moiety was done by the 1,3-Dicyclo-hexylcarbodiimide(DCC). The carboxylated sulfonamide conjugated block copolymer shows the pH & themo-sensitivity. Diblock (MPEGPDLLA- SA, MPEG-PCLA-SA) is shown the micelle-demicelle behavior with the narrow pH range (pH 7.2 7.8). Also, triblock copolymer (SA-PCLA-PEG-PCLA-SA) is shown the sol-gel phase transition with pH & temperature change. Triblock copolymer solution (pH 8.0) flows at the room temperature (20?). As this solution is injected into the buffer solution (pH 7.4, 37?), the triblock copolymer hydrogel forms the gel in the buffer solution (pH 7.4, 37?). But, triblock copolymer hydrogel doesn``t form the gel in the buffer solution (pH 8.0, 37?). These micelle and hydrogels are considered to be used as a good carrier for the protein & drug delivery.
A-31 : pH-sensitive block copolymer micelle
심우선,이두성 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.2
MPEG-PDLLA & MPEG-PCLA block copolymers were synthesized by a ring-opening copolymerization of D,L- lactide and ε-caprolactone with MPEG (monomethoxy poly (ethylene glycol)) as an initiator, respectively. The sulfamethazine was modified with succinic anhydride to conjugate the block copolymer with pH-sensitive moiety (sulfamethazine). Also, the oligo-sulfamethazine(OSM) was obtained by the radical polymerization with transfer agent. The conjugation of the block copolymer and modified sulfamethazine (or oligo-sulfamethazine) was done by the DCC coupling reaction. The micelles of the synthesized pH-sensitive biodegradable block copolymers were characterized by the fluorescence method in the various buffer solutions. Also, the micelle size was certificated by DLS. The critical micelle concentration of pH-sensitive block copolymers decreases with increasing the hydrophobic block length, and increases with increasing the pH of buffer solutions. Also, the pH-sensitive block copolymers show the micelle integration-disintegration due to the pH change at the constant concentration. This pH-sensitive block copolymer makes the drug targeting available, so it is expected to be applied as a superior drug carrier.
심우선,황영민,박선규,이천구,강내규 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.6
The purpose of this study is to find an optimum composition of microneedles that penetrate the skin and rapidly dissolve within the cutaneous layer in a few minutes. A micromolding method was introduced to prepare drug?loaded dissolving microneedles by using biocompatible, water?soluble polymers such as carboxymethylcellulose, hyaluronic acid, and polyvinylpyrrolidone (PVP). The microneedles had a sharp structure with a needle tip of about 5 ?m. The microneedles penetrated into the skin with 90% skin penetration rate, and they were dissolved within minutes to release the drug. An increase in the content of PVP in the microneedle increased the dissolution rate of the microneedles in the skin and the needle strength to penetrate the skin, and resulted in an increased skin permeation of the drug. The drug?loaded microneedles were applied to the wrinkles shown around the eyes (crow's feet) of female subjects for 8 weeks, and we observed statistically significant disappearance of wrinkle after 4 weeks. The newly developed dissolving needles showed efficient drug delivery and can be considered a valuable, high?functioning, potential wrinkle improving treatment.