Publications by authors named "Chung Wook Chung"

Endo-β-1,3-glucanase is a glycoside hydrolase (GH) that plays an essential role in the mineralization of β-glucan polysaccharides. In this study, the novel gene encoding an extracellular, non-modular GH16 endo-β-1,3-glucanase (GluH) from PAMC 29290 isolated from Arctic marine sediment was discovered through an analysis of its whole genome sequence and subsequently overexpressed in BL21. The 870-bp GluH gene encoded a protein featuring a single catalytic GH16 domain that shared over 61% sequence identity with uncharacterized endo-β-1,3-glucanases from diverse species, as recorded in the National Center for Biotechnology Information database.

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Poly(3-hydroxybutyrate) (PHB) is a versatile thermoplastic with superior biodegradability and biocompatibility that is intracellularly accumulated by numerous bacterial and archaeal species. sp. strain JY310 that was able to efficiently biotransform reducing sugars in d-xylose-rich rice husk hydrolysate (reducing sugar) to PHB was isolated from the soil of a rice paddy.

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Endo-type chitinase is the principal enzyme involved in the breakdown of -acetyl-d-glucosamine-based oligomeric and polymeric materials through hydrolysis. The gene (966-bp) encoding a novel endo-type chitinase (ChiJ), which is comprised of an N-terminal chitin-binding domain type 3 and a C-terminal catalytic glycoside hydrolase family 19 domain, was identified from a fibrolytic intestinal symbiont of the earthworm , HY-13. The highest endochitinase activity of the recombinant enzyme (rChiJ: 30.

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Nanophotosensitizer composed of methoxy poly(ethylene glycol) (MePEG) and chlorin e6 (Ce6) (abbreviated as Pe6) was synthesized for efficient delivery of Ce6 to the colon cancer cells. Pe6 nanophotosensitizer has small diameter less than 100 nm with spherical shape and core-shell structure. They were activated in aqueous solution while Ce6 was quenched due to its poor aqueous solubility.

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Analysis of mixed microbial populations responsible for the production of medium-chain-length polyhydroxyalkanoates (MCL-PHAs) under periodic substrate feeding in a sequencing batch reactor (SBR) was conducted. Regardless of activated sludge samples and the different MCL alkanoic acids used as the sole external carbon substrate, denaturing gradient gel electrophoresis analysis indicated that Pseudomonas aeruginosa was the dominant bacterium enriched during the SBR process. Several P.

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Objectives: To evaluate the biocatalytic characteristics of a new endo-β-1,4-D-mannan-degrading enzyme (ManP) from Paenibacillus sp. strain HY-8, a gut bacterium of the longicorn beetle Moechotypa diphysis.

Results: Purified ManP (32 kDa) with an N-terminal amino acid sequence of APSFAVGADFSYVPG displayed the greatest degree of biocatalytic activity toward locust bean gum (LBG) at 55 °C and pH 7.

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We synthesized methoxy poly(ethylene glycol) (MPEG)-chlórin e6 (Ce6) conjugates to increase aqueous solubility of Ce6, to fabricate nanoparticles, and to improve tumor targetability of Ce6. MPEG-Ce6 conjugates (abbreviated as Pe6) associated in the aqueous solution as a nanoparticle. Pe6 nanoparticles have small diameter less than 100 nm, spherical shape, and core-shell structure in the aqueous environment.

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Smart delivery system of photosensitizer chlorin e6 (Ce6) has been developed for targeted photodynamic therapy (PDT). Simple self-assemblies of the mixtures comprising soybean lecithin derived phosphatidylcholine (PC), phosphatidylethanolamine-poly(L-histidine)40 (PE-p(His)40), and folic acid (FA) conjugated phosphatidylethanolamine-poly(N-isopropylacrylamide)40 (PE-p(NIPAM)40-FA) in different ratios yield smart nanospheres characterized by (i) stable and uniform particle size (∼100 nm), (ii) positive surface charge, (iii) high hydrophobic drug (Ce6) loading efficiency up to 45%, (iv) covalently linked targeting moiety, (v) low cytotoxicity, and (vi) smartness showing p(His) block oriented pH and p(NIPAM) oriented temperature responsiveness. The Ce6-encapsulated vesicular nanospheres (Ce6@VNS) were used to confirm the efficiency of cellular uptake, intracellular distribution, and phototoxicity against KB tumor cells compared to free Ce6 at different temperature and pH conditions.

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A series of temperature-responsive lipopolymers have been synthesized by bioconjugating poly(N-isopropylacrylamide) (n = 25, 40, 60) onto three different phospholipids by the combination of reversible addition fragmentation chain transfer polymerization and azide-alkyne click reactions. To achieve the active targeting of cancer cells, folic acid (FA) has also been tethered to the resulting hybrid materials. The doxorubicin (Dox) encapsulated uniform nanocarriers (150 nm in diameter) fabricated by the self-assembly of the lipopolymers display temperature responsive controlled release.

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Article Synopsis
  • The gene for a GH6 endo-β-1,4-glucanase enzyme (CelL) was cloned from the bacterium Cellulosimicrobium funkei and characterized, revealing its structure and function.
  • CelL is a 56.0 kDa enzyme that functions optimally at 50°C and pH 5.0, effectively breaking down various cellulosic materials but showing limited activity against certain carbohydrates.
  • The enzyme demonstrates strong binding to substrates like Avicel and chitin, while it has weaker interactions with other polymers such as lignin and poly(3-hydroxybutyrate).
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We fabricated cisplatin-incorporated nanoparticles using block copolymer composed of methoxy poly(ethylene glycol) (MPEG) and poly(L-glutamic acid) (PGA) (abbreviated as GE). For synthesis of block copolymer, MPEG was directly conjugated to the terminal amine of PGA. Cisplatin-incorporated nanoparticles was prepared by ion complex formation of cisplatin and PGA domain of block copolymer.

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Intracellular protoporphyrin IX (PpIX) generation following administration of 5-aminolevulinic acid (ALA) has been used in photodynamic therapy (PDT). Subsequent irradiation can lead to selective damage to photosensitizer-treated cells or tissues. In the present work, we describe the enhancement of ALA-induced PpIX accumulation using a liposome carrier.

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Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a (1)H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.

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In this study, the effect of chlorin e6-based photodynamic therapy (Ce6-PDT) was investigated in human intrahepatic (HuCC-T1) and extrahepatic (SNU1196) cholangiocarcinoma (CCA) cells. The amount of intracellular Ce6 increased with increasing Ce6 concentration administered, or with incubation time, in both cell lines. The ability to take up Ce6 and generate reactive oxygen species after irradiation at 1.

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Biocompatible lipo-histidine hybrid materials conjugated with IR820 dye show pH-sensitivity, efficient intracellular delivery of doxorubicin (Dox), and intrinsic targetability to cancer cells. These new materials form highly uniform Dox-loaded nanosized vesicles via a self-assembly process showing good stability under physiological conditions. The Dox-loaded micelles are effective for suppressing MCF-7 tumors, as demonstrated in vitro and in vivo.

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Purpose: Nanoparticles based on stimuli-sensitive drug delivery have been extensively investigated for tumor targeting. Among them, pH-responsive drug targeting using pH-sensitive polymers has attracted attention because solid tumors have an acidic environment. A dextran-b-poly(L-histidine) (DexPHS) copolymer was synthesized and pH-responsive nanoparticles were fabricated for drug targeting.

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The aim of this study was to investigate the effect of the combination of vorinostat and epigallocatechin-3-gallate against HuCC-T1 human cholangiocarcinoma cells. A novel chemotherapy strategy is required as cholangiocarcinomas rarely respond to conventional chemotherapeutic agents. Both vorinostat and EGCG induce apoptosis and suppress invasion, migration, and angiogenesis of tumor cells.

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Chitosan was hydrophobically modified with ursodeoxycholic acid (UDCA) to fabricate nano-photosensitizer for photodynamic therapy (PDT) of HuCC-T1 cholangiocarcinoma cells. Synthesis of UDCA-conjugated chitosan (ChitoUDCA) was confirmed using (1)H NMR spectra. Chlorin E6 (Ce6) was used as a photosensitizer and incorporated into ChitoUDCA nanoparticles through formation of ion complexes.

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5-Aminolevulinic acid (ALA)-based photodynamic therapy (PDT) has the potential to kill cancer cells via apoptotic or necrotic signals that are dependent on the generation of intracellular reactive oxygen species (ROS). Celecoxib is an anti-inflammatory drug that induces intracellular ROS generation. We investigated whether the combined application of celecoxib and ALA-PDT improved the efficacy of PDT in human cholangiocarcinoma cells and in tumor bearing mice.

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Background: Cholangiocarcinoma is a malignant tumor arising from the epithelium of the bile ducts. In this study, we prepared sorafenib-loaded biliary stents for potential application as drug-delivery systems for localized treatment of extrahepatic cholangiocarcinoma.

Methods: A sorafenib-coated metal stent was prepared using an electrospray system with the aid of poly(ε-caprolactone) (PCL), and then its anticancer activity was investigated using human cholangiocellular carcinoma (HuCC)-T1 cells in vitro and a mouse tumor xenograft model in vivo.

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A series of dual stimuli responsive synthetic polymer bioconjugate chimeric materials, poly(N-isopropylacrylamide)55-block-poly(L-histidine)n [p(NIPAM)55-b-p(His)n] (n=50, 75, 100, 125), have been synthesized by employing reversible addition-fragmentation chain transfer polymerization of NIPAM, followed by ring-opening polymerization of α-amino acid N-carboxyanhydrides. The dual stimuli responsive properties of the resulting biocompatiable and membrenolytic p(NIPAM)55-b-p(His)n polymers are investigated for their use as a stimuli responsive drug carrier for tumor targeting. Highly uniform self-assembled micelles (∼55 nm) fabricated by p(NIPAM)55-b-p(His)n polymers display sharp thermal and pH responses in aqueous media.

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Purpose: The aim of this study was to make 5-aminolevulinic acid (5-ALA)-incorporated nanoparticles using methoxy polyethylene glycol/chitosan (PEG-Chito) copolymer for application in photodynamic therapy for colon cancer cells.

Methods: 5-ALA-incorporated (PEG-Chito-5-ALA) nanoparticles were prepared by ion complex formation between 5-ALA and chitosan. Protoporphyrin IX accumulation in the tumor cells and phototoxicity induced by PEG-Chito-5-ALA nanoparticles were assessed using CT26 cells in vitro.

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Hexyl-aminolevulinic acid (HALA) was compared with aminolevulinic acid (ALA) in terms of improving ALA-based photodynamic therapy (PDT) for human intra- and extrahepatic cholangiocarcinoma (CCA) HuCC-T1 and SNU1196 cells. Because of the different uptake mechanisms of HALA, a relatively higher amount of protoporphyrin IX (PpIX) was induced in the both CCA cell types at low concentrations of HALA. Furthermore, higher expression of porphobilinogen deaminase, coproporphyrinogen III oxidase, and protoporphyrinogen oxidase, the key enzymes for synthesizing PpIX in the heme biosynthetic pathway, facilitated the exuberant generation of PpIX in HuCC-T1 cells.

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Background: 5-Aminolevulinic acid (ALA) and its derivatives have been widely used in photodynamic therapy. The main drawback associated with ALA-based photodynamic therapy (ALA-PDT) and ALA fluorescence diagnosis results from the hydrophilic nature of ALA and lack of selectivity for tumor versus nontumor cells. The application of certain triggers, such as pH, into conventional sensitizers for controllable (1)O(2) release is a promising strategy for tumor-targeted treatment.

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Background: The study investigated the use of combined photodynamic therapy (PDT) and stent placement for the treatment of cholangiocarcinoma (CC). For this purpose, 5-aminolevulinic acid (ALA) was incorporated into poly(vinyl alcohol) (PVA) nanofiber, and coated onto metal stents. Their efficacy was assessed in PDT towards HuCC-T1 CC cells.

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