• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2635-2641
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• 2012

Novel silver/salep-g-poly(acrylic acid) nanocomposite hydrogel were prepared in aqueous solution using poly(acrylic acid) grafted onto salep as a biopolymer based material. FT-IR spectra confirmed that poly(acrylic acid) (PAA) had been grafted onto salep in graft copolymerization reaction. TEM observations showed that silver nanoparticles have been uniformly dispersed in polymeric matrix. Effects of pH, acrylic acid (AA) amount and silver ion concentration on swelling capabilities were investigated. Results indicate that modifying AA and silver ion can improve swelling properties of the resultant nanocomposite hydrogel. pH response of this nanocomposite hydrogel in acidic and neutral pH made it suitable for drug delivery applications.

• Macromolecular Research
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• v.17 no.5
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• pp.307-312
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• 2009

Core-shell hydrogel nanocomposite was fabricated by encapsulating a silica-gold nanoshell (SGNS) with poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-AAc) copolymer. The oleylamine-functionalized SONS was used as a nanotemplate for the shell-layer growth of hydrogel copolymer. APS (ammonium persulfate) was used as a polymerization initiator to produce a hydrogel-encapsulated SGNS (H-SGNS). The amounts of NIPAM (N-isopropylacrylamide) monomers were optimized to reproduce the hydrogel-encapsulated SGNS. The shell-layer thickness was increased with the increase of polymerization time and no further increase in the shell-layer thickness was clearly observed over 16 h. H-SGNS exhibited the systematic changes of particle size corresponding to the variation of pH and temperature, which was originated from hydrogen-bonding interaction between PNIPAM amide groups and water, as well as electrostatic forces attributed by the ionization of carboxylic groups in acrylic acid.

• YAKHAK HOEJI
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• v.43 no.2
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• pp.150-159
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• 1999

Hollow type suppositories inserted polyvinyl alcohol (PVA) hydrogel capsule containing propranolol·HCI (PPH) were prepared using different bases, polyethylene glycol (PEG), Witepsol H-15 (WH-15) and Witepsol W-35 (WW-35) to improve the controlled release of PPH. The release of PPH from the hollow type suppository inserted PVA hydrogel capsule was retarded than that from PEG, WH-15, or WW-35 hollow type suppositories in rat rectal cavity. When the suppositories were administered to rats, the controlled release of PPH was proved by the plasma concentration-time-profiles of PPH. No significant difference (p〈0.05) among the three different hollow type suppositories was observed in terms of AUC and MRT of PPH. WH-15 hollow type suppository inserted 12% of PVA hydrogel capsule caused irritation to rat rectal mucosa. However, the WH-15 hollow type suppository inserted PVA hydrogel capsule caused no severe irritation on rectal mucosa. The application of the hollow type suppositories using PVA in sustained rectal delivery of drugs might be feasible.

• International Journal of Industrial Entomology and Biomaterials
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• v.36 no.1
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• pp.10-14
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• 2018

A photo-crosslinkable sericin hydrogel has been prepared by introducing methacrylate groups on sericin. Lysine was the amino acid for methacrylation and the degree of methacrylation was increased with the amount of methacrylic anhydride added. When the concentration of methacrylic anhydride was 20% of sericin, 0.635 mmol/g of methacrylate group could be introduced. The storage modulus of sericin hydrogel was increased proportionally with the degree of methacrylation. However, the swelling ratio of sericin hydrogel decreased with the increase of methacrylation.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.6
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• pp.829-834
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• 2015

A simple and sensitive hydrogel-based detecting gel has been presented for the qualitative determination of cyanogen chloride(CK) using Konig reaction. To optimize Konig reaction conditions, the effects of pyridine and barbituric acid concentration were investigated. Under the optimized conditions, CK gas concentration was directly related with absorbance change at 567 nm. Based on aqueous solution test results, we finally prepared CK detecting hydrogel by absorbing pyridine and barbituric acid solution. Color change of the prepared CK detecting hydrogel was clearly observed when the detecting gel was exposed to 10 ppm CK gas.

• Polymer(Korea)
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• v.38 no.5
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• pp.588-595
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• 2014

A semi-interpenetrating polymer network (semi-IPN) hydrogel composed of crosslinked chitosan and poly (acrylic acid-co-crotonic acid) was prepared in the presence of glutaraldehyde (GA) as a crosslinker. Fourier-transform infrared, thermogravimetric analysis and scanning electron microscopy were employed to confirm the structure of the semi-IPN hydrogel. The swelling capacity of hydrogel was shown to be affected by the monomers weight ratio, chitosan content, initiator and GA concentrations. The results also indicated that the semi-IPN hydrogel had different swelling capacity at various pHs. Additionally, the swelling behavior of the hydrogel was investigated in aqueous solutions of NaCl, $CaCl_2$, and $AlCl_3$.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2680-2686
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• 2009

The synthesis of a novel superabsorbent hydrogel with natural hybrid backbone via graft copolymerization of acrylamide (AAm) onto kappa-carrageenan (kC, as a polysaccharide) and gelatin (as a protein) under classic thermal conditions is described. The Taguchi method as a strong experimental design tool was used for synthesis optimization. A series of hydrogels were synthesized by proposed conditions of Qualitek-4 Software. Considering the results of 9 trials according to analysis of variance (ANOVA), optimum conditions were proposed. The swelling behavior of optimum hydrogel was measured in various solutions with pH values ranging from 1 to 13. In addition, swelling kinetics, swelling in various organic solvents, various salt solutions and On–Off switching behavior were investigated. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetrical analysis (TGA). Surface morphology of the synthesized hydrogels was assessed by scanning electron microscope (SEM).

• Journal of Sensor Science and Technology
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• v.20 no.4
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• pp.234-237
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• 2011

This paper presents a study into pH Indicator-Embedded hydrogel micro-particles which are encoded various shapes according to the captured indicator. We incorporate various pH indicators into a photo-curable hydrogel, PEG-DA(Poly(ethylene glycol) diacrylate). Using the latest fluidic lithography techniques, we can easily fabricate variously patterned hydrogel particles based on in-situ photopolymerization of the PEG-DA in a micro-fluidic channel. The shape of the particle is related to the pH indicator inside the particle. We demonstrate that the micro pH sensors change their colors according to the pH levels. The micro pH sensors have various characteristics that are related to the curing time, particle size, etc. By changing these conditions, we can adjust the long term stability and reaction time of the hybrid micro pH sensors.

• Journal of Sericultural and Entomological Science
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• v.54 no.1_2
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• pp.6-16
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• 2016

Both mechanical property and biocompatibility of silk protein has been highlighted for decades and lots of studies are trying to use it for a wide variety of applications. Recently, silk-based hydrogel has received great attention in biomedical field such as drug delivery and tissue engineering since silk protein presents a unique hydrogel forming mechanism as well as cyto-compatibility. Silk hydrogels are formed via tremendous physical and chemical techniques and their biomedical applications are extensively explored. In this review, various types and fabrication methods of silk hydrogels are presented and also the recent research trend of silk hydrogel-based applications is summarized.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.10
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• pp.38-43
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• 2021

Photocurable hydrogels are widely used as 3D printing materials in tissue engineering (e.g., scaffold fabrication) as well as optical fibers (or optical sensors) materials. Photocurable hydrogels can control optical and mechanical properties such as chemical or fabrication conditions. In previous research, we introduced a new 3D printing method to fabricate a freestanding overhanging hydrogel structure without supporting structure. This study was measured and analyzed the difference of the mechanical properties of the photocurable hydrogel according to the light intensity using a micro tensile tester. In practically, it was difficult to perform a direct tensile test on a micro (less than 1 mm) size fiber. In this study, the tensile test of the hydrogel fibers could be measured simply and repeatedly using a paper carrier.