• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3191-3195
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• 2012

New silver nanoparticle (AgNP)-loaded amino acid based hydrogels were synthesized successfully from poly (vinyl alcohol) (PVA) and poly(acryl amide-co-acryloyl phenyl alanine) (PAA) by redox polymerization. The formation of AgNP in hydrogels was confirmed by using a UV-Vis spectrophotometer and XRD. The structure and morphology of silver nanocomposite hydrogels were studied by using a scanning electron microscopy (SEM), which demonstrated scattered nanoparticles, ca. 10-20 nm. Thermogravimetric analysis revealed large differences of weight loss (i.e., 48%) between the prestine hydrogel and silver nanocomposite. The antibacterial studies of AgNP-loaded PAA (Ag-PAA) hydrogels was evaluated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. These Ag-PAA hydrogels showed significant activities against all the test bacteria. Newly developed hydrogels could be used for medical applications, such as artificial burn dressings.

• Macromolecular Research
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• v.12 no.2
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• pp.219-224
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• 2004

In this work, we prepared hydrogels for wound dressing from a mixture of poly(vinyl alcohol) (PVA) and alginate using the $\^$60/Co ${\gamma}$-ray irradiation technique. We examined the physical properties of these hydrogels, including gelation, water absorptivity, and gel strength, to evaluate the applicability of these hydrogels for wound dressings. The biocompatibility of these hydrogels was also evaluated in vitro, in cultures of mouse fibroblasts, and in vivo, by subcutaneous implantation studies in rats. The gel content and strength increased upon increasing the radiation dose and upon decreasing the concentration of alginate. The degree of swelling was inversely proportional to the gel content and strength. The degree of cytotoxicity of the ${\gamma}$-ray-treated hydrogels was ca. 60% compared to the (－) control (serum) after 1 day of incubation. When the incubations were prolonged up to 2 days, the toxicity of all the samples decreased remarkably and reached that of the control. Subcutaneous implantation studies in rats indicated that foreign body reactions occurring around the implanted hydrogels were moderate and became minimal upon increasing the implantation time.

• Archives of Pharmacal Research
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• v.24 no.1
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• pp.69-73
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• 2001

Biodegradable hydrogels based on glycidyl methacrylate dextran (CMD) and dimethacrylate poly(ethylene glycol) (DMP) were proposed for colon-specific drug delivery. GMD was synthesized by coupling of glycidyl methacylate with dextran in the presence of 4-(N, N-dimethylamino)pyridine (DMAP) using dimethylsulfoxide as a solvent. Methacrylate-terminated poly (ethylene glycol) (PEG) macromer was prepared by the reaction of PEG with methacryloyl chloride. CMD/DMP hydrogels were prepared by radical polymerization of phosphate buffer solution (0.1 M, pH 7.4) of GMD and DMP using ammonium peroxydisulfate (APS) and UV as initiating system. The synthetic GMD, DMP and GMD/DMP hydrogels were characterized by fourier transform infrared (FT-lR) spectroscopy. The FITC-albumin loaded hydrogels were prepared by adding FITC-albumin solution before UV irradiation. Swelling capacity of GMD/DMP hydrogels was controlled not only by molecular weight of dextran, but also by incorporation ratio of DMP Degradation of the hydrogels has been studied in vitro with dextranase. FITC-albumin release from the GMD/DMP hydrogels was affected by molecular weight of nextran and the presence of dextranase in the release medium.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.229-230
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• 1998

Triblock copolymers from poly(ethylene glycol) (PEG) and D,L-lactide or $\varepsilon$-carprolactone were synthesized to prepare semi-interpenetrating polymer network (semi-IPN) with chitosan by U.V. irradiation method. Then, solute permeation through these semi-IPNs hydrogels were investigated. The structures of semi-IPNs were confirmed by FT-IR spectroscopy and wide angle X-ray diffractometer (WAXD). Equilibrium water content (EWC) of these hydrogels was in the range of 67-75%. The crystallinity, thermal properties and mechanical properties of semi-IPNs hydrogels were studied. All the hydrogels revealed a remarkable decrease in crystallinity as compared with PEG macromer itself. The tensile strengths of semi-IPNs hydrogels in dry state were rather high, but those of hydrogels in wet state decreased drastically. The permeabilities of solutes of hydrogels followed the swelling behaviors and were regulated by solute size.

• Macromolecular Research
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• v.17 no.3
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• pp.156-162
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• 2009

Supramolecular hydrogels were instantaneously fabricated by mixing aqueous solutions of $\alpha$-cyclodextrins ($\alpha$-CDs) and amphiphilic methoxy (polyethylene glycol) (MPEG)-$\varepsilon$-caprolactone (CL) oligomer, which was synthesized via the ring-opening polymerization of the CL monomer using low-molecular-weight MPEG ($M_n$ of MPEG=2,000 g/mol) as an initiator. The supramolecular structure of the hydrogels was revealed by X-ray diffraction (XRD) analyses. Rheological studies of the hydrogels revealed an elastic character when the number of CL units in the oligomer was more than 2, and the obtained hydrogels showed high storage modulus but relatively low shearing viscosity due to the low-molecular-weight character of the oligomer, which was more preferable for use as an injectable delivery system. The physical properties of the hydrogels could be modulated by controlling the chain morphology and concentration of the oligomers, as well as the feed molar ratio of the oligomer to $\alpha$-CD. The components of the supramolecular hydrogels are biocompatible and can readily be eliminated from the body. These features render the supramolecular hydro gels suitable as drug delivery systems and tissue engineering scaffolds.

• Journal of the Korean Chemical Society
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• v.50 no.6
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• pp.447-453
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• 2006

of synthetic conditions and water content on rheological properties of polyacrylamide hydrogels were studied. The non-Newtonian flow curves of polyacrylamide hydrogels were obtained by using a cone-plate rheometer. The rheological parameters were obtained by applying non-Newtonian equation to the flow curves for polyacrylamide hydrogels. The polyacrylamide hydrogels are shear thinning under increasing shear rate modes which result in thixotropic behavior. These flow properties are controlled by the characteristics of flow units and the interaction among the flow segments.

• Radioisotope journal
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• v.21 no.4
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• pp.46-54
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• 2006

Biocompatible and biodegradable hydrogels based on carboxymethyl cellulose(CMC) and polyethyleneglycol(PEG) were prepared far physical barriers for preventing surgical adhesions. These interpolymeric hydrogels were synthesized by a gamma irradiation crosslinking technique. The 1Scmxl.Scm of cecal serosa and adjacent abdominal wail were abraded with bane burr until tbe serosal surface was disrupted and hemorrhagic but not perforated. and the serosa of tbe cecum was sutured to the abdominal wall in 5mm apart from the injured sire. The denuded cecum was covered with either CMC/PEG hydrogels or solution from CMC/PEG hydrogel. Control rat serosa was not covered. Two weeks later. the rats were sacrificed and adhesion was scored on a 0-5 scale. No treatment showed the significantly higher incidence of adhesions than either CMC/BEC hydrogels or solution from CMC/PEG hydrogel. In conclusion, these studies demonstrate that CMC/BEG hydrogels have a function of prevention of intra abdominal adhesion in a rat model.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.443-446
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• 2017

This study investigated the physical properties of polymers and antimicrobial activities of organic acids on Listeria monocytogenes to develop hydrogels. ${\kappa}-carrageenan$ (1, 2, and 3%), carboxymethylcellulose (CMC; 1, 3, and 5%), and agar (1.5 and 3%) were mixed with cross-linkers ($Na^+$, $K^+$, $Ca^{2+}$, and $Al^{3+}$) or each other by stirring or heating to form cross-linkage, and their physical properties (hardness, elasticity, and swelling) were measured. The hydrogels formulated with organic acid (1, 3, and 5%) were analyzed by spot assay against L. monocytogenes. ${\kappa}-carrageenan$ formed hydrogels with high hardness without other cross-linkers, but they had low elasticity. The elasticity was improved by mixing with other cross-linkers such as $K^+$ or other polymer, especially in 3% ${\kappa}-carrageenan$. CMC hydrogel was formed by adding cross-linkers $Al^{3+}$, $Na^+$, or $Ca^{2+}$, especially in 5% CMC. Thus, stickiness and swelling for selected hydrogel formulations (two of ${\kappa}-carrageenan$ hydrogels and three of CMC hydrogels) were measured. Among the selected hydrogels, most of them showed appropriate hardness, but only 3% ${\kappa}-carrageenan-contained$ hydrogels maintained their shapes from swelling. Hence, 3% ${\kappa}-carrageenan+0.2%$ KCl and 3% ${\kappa}-carrageenan+1%$ alginate+0.2% KCl+0.2% $CaCl_2$ were selected to be formulated with lactic acid, and showed antilisterial activity. These results indicate that 3% ${\kappa}-carrageenan$ hydrogels formulated with lactic acid can be used to control L. monocytogenes on food surface.

• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.1
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• pp.23-32
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• 2015

Facile immobilization of growth factors in hyaluronic acid (HA) hydrogels using dual enzymes is reported in the paper. The hydrogels were formed by using horseradish peroxidase (HRP) and hydrogen peroxide ($H_2O_2$) and transforming growth factor-${\beta}3$ (TGF-${\beta}3$) was covalently conjugated on the hydrogels in situ using tyrosinase (Ty) without any modifications. For the preparation of hydrogels, HA was grafted with poly(ethylene glycol) (PEG), which was modified with a tyrosine. The gelation times of the HA hydrogels were ranging from 415 to 17 s and the storage moduli was dependent on the concentration of $H_2O_2$ and Ty (470-1600 Pa). A native TGF-${\beta}3$ (200 ng/mL) was readily encapsulated in the HA hydrogels and 17% of the TGF-${\beta}3$ was released over 1 month at the Ty concentration of 0.5 KU/mL, while the release was faster when 0.3 KU/mL of Ty was used for the encapsulation (27%). It can be suggested that the growth factors resident in the hydrogels for a long period of time may lead cells proliferating and differentiating, whereas the growth factors that are initially released from the hydrogels can induce the ingrowth of cells into the matrices. Therefore, the dual enzymatic methods as facile gel forming and loading of various native growth factors or therapeutic proteins could be highly promising for tissue regenerative medicines.

• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.1
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• pp.1-12
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• 2014

Polymer multilayered hydrogels were prepared on a titanium alloy (Ti) substrate using a layer-by-layer (LBL) process to load a cell growth factor. Two water-soluble polymers were used to fabricate the multilayered hydrogels, a phospholipid polymer with both N, N-dimethylaminoethyl methacrylate (DMAEMA) units and 4-vinylphenylboronic acid (VPBA) units [poly(MPC-co-DMAEMA-co-VPBA) (PMDV)], and the polysaccharide alginate (ALG). PMDV interacted with ALG through a selective reaction between the VPBA units in PMDV and the hydroxyl groups in ALG and through electrostatic interactions between the DMAEMA units in PMDA and the anionic carboxyl groups in ALG. First, the Ti substrate was covered with photoreactive poly vinyl alcohol, and then the Ti alloy was alternately immersed in the respective polymer solutions to form the PMDV/ALG multilayered hydrogels. In this multilayered hydrogel, vascular endothelial growth factor (VEGF) was introduced in different layers during the LbL process under mild conditions. Release of VEGF from the multilayered hydrogels was dependent on the location; however, release continued for 2 weeks. Endothelial cells adhered to the hydrogel and proliferated, and these corresponded to the VEGF release profile from the hydrogel. We concluded that multilayered hydrogels composed of PMDV and ALG could be loaded with cell growth factors that have high activity and can control cell functions. Therefore, this system provides a cell function controllable substrate based on the controlled release of biologically active proteins.