• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.3
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• pp.163-174
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• 2014

The objective of this study is to prepare an artificial extracellular matrix (ECM) for cell culture by using polymer hydrogels. The polymer used is a cytocompatible water-soluble phospholipid polymer: poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-n-butyl methacrylate-p-nitrophenyloxycarbonyl poly(ethylene oxide) methacrylate (MEONP)] (PMBN). The hydrogels are prepared using a cross-linking reaction between PMBN and diamine compounds, which can easily react to the MEONP moiety under mild conditions. The most favorable diamine is the bis(3-aminopropyl) poly(ethylene oxide) (APEO). The effects of cross-linking density and the chemical structure of cross-linking molecules on the mechanical properties of the hydrogel are evaluated. The storage modulus of the hydrogel is tailored by tuning the PMBN concentration and the MEONP/amino group ratio. The porous structure of the hydrogel networks depends not only on these parameters but also on the reaction temperature. We prepare a hydrogel with $40-50{\mu}m$ diameter pores and more than 90 wt% swelling. The permeation of proteins through the hydrogel increases dramatically with an increase in pore size. To induce cell adhesion, the cell-attaching oligopeptide, RGDS, is immobilized onto the hydrogel using MEONP residue. Bovine pulmonary artery endothelial cells (BPAECs) are cultured on the hydrogel matrix and are able to migrate into the artificial matrix. Hence, the RGDS-modified PMBN hydrogel matrix with cross-linked APEO functions as an artificial ECM for growing cells for applications in tissue engineering.

• Membrane Journal
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• v.29 no.4
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• pp.231-236
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• 2019

In this study, alginate-based hydrogel membranes composed of hydrogel beads and highly tough hydrogel matrix including moisturizing oil and natural emulsifier were prepared and their elution characteristics were evaluated. As a result, it was confirmed that the elution rate of the moisturizing oil component can be controlled within a desired range by controlling the composition of the hydrogel bead and the tough hydrogel matrix. In particular, it has been confirmed that by combining tough hydrogel having a structure of interpenetrating polymer network (IPN) and hydrogel beads, the physical stability of the membranes can be improved and the elution rate of the moisturizing oil can also be controlled more finely.

• Journal of Pharmaceutical Investigation
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• v.26 no.2
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• pp.137-144
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• 1996

The study was carried out for the preparation and evaluation of a buoyant hydrogel matrix (BHM), which is buoyant in a neutral or in pH 2.0 buffer solution, by the aspects of buoyancy, swelling, and drug release. Physical mixtures of HPC and CP in various molar ratio were employed as a mucoadhesive polymer which swells and controls the rate of drug release. Anhydrous citric acid and sodium bicarbonate in the molar ratio of 1:3 were employed as effervescing agents which provide a buoyancy for the mucoadhesive polymeric matrix. The buoyancy in vitro was expressed as both floating time$(T_{fl})$ and surfing time$(T_{sf})$, which are the time required for floating from the bottom to the surface of the medium and the time to keep the floated state at the surface of medium during release studies, respectively. A close relationship was observed between the buoyancy and the amount of effervescing agent added. $T_{fl}$ of the buoyant hydrogel matrices were decreased to about 10 seconds linearly with increasing the amount of effervescing agent in the range of 5 to 15%. $T_{sf}$ of the buoyant hydrogel matrices were varied from 1 to 3 hr depending on the amount of effervescing agent. The swelling was observed by changes in diameter of the buoyant hydrogel matrices in distilled water or acidic buffer solution, resulted in dependences on pH and the amount of effervescing agents. The release of hydrochlorothiazide from the buoyant hydrogel matrices were followed by apparent zero-order kinetics, while the buoyant hydrogel matrices were floated at the surface and maintaining their swollen shapes.

• Smart Structures and Systems
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• v.7 no.3
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• pp.213-222
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• 2011

The native extracellular matrix (ECM) consists of an integrated fibrous protein network and proteoglycan-based ground (hydrogel) substance. We designed a novel electrospinning technique to engineer a three dimensional fiber-hydrogel composite that mimics the native ECM structure, is injectable, and has practical macroscale dimensions for clinically relevant tissue defects. In a model system of articular cartilage tissue engineering, the fiber-hydrogel composites enhanced the biological response of adult stem cells, with dynamic mechanical stimulation resulting in near native levels of extracellular matrix. This technology platform was expanded through structural and biochemical modification of the fibers including hydrophilic fibers containing chondroitin sulfate, a significant component of endogenous tissues, and hydrophobic fibers containing ECM microparticles.

• Korean Membrane Journal
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• v.6 no.1
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• pp.37-43
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• 2004

Comb-type graft hydrogels composed of alginate and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to manifest rapid temperature and pH sensitivity. To appear the electro-sensitivity, the polyaniline, conducting polymer, was added into the matrix. The swelling kinetics and ratios were compared under the various compositions of polyaniline. The swelling behaviors revealed that conducting polymer/hydrogel composites could control the swelling ratio and kinetics. The addition of polyaniline in the matrix improved the thermal stability in comparison with that of the hydrogel without polyaniline. In temperature sensitivity, the adding the polyaniline into the matrix decreased the degree of change in the swelling ratio. The swelling ratios continuously increased with increasing pH values. The drug release rate from the hydrogel increased with the adding the polyaniline and the applying the direct voltage to the hydrogels.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.700-705
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• 2013

This study was initiated to evaluate hydrophilic polymers (hydrogels) as a new solid matrix medium for seed-priming of Heteropappus arenarius Kitam. Solid matrix priming (SMP)-media were prepared with the combination of Na- and K-based hydrogels and hydrogels with three different dry levels (DC; 70%, 80%, and 90%). Priming was performed in the dark at 15 or $20^{\circ}C$ for 24 hours, and all primed seeds were incubated at $20^{\circ}C$ in the dark for the germination test. Non-primed seeds and seeds primed with distilled water (DW) were also included. To reach the germination rate of 50% ($T_{50}$), it took 4.0 days for non-primed seeds, and 3.6 and 3.9 days for DW-primed seeds at 15 and $20^{\circ}C$, respectively. Na-based hydrogel-primed seeds with 70% DC (Na 70%) showed the fastest germination, which respectively took and 1.9 and 1.8 days at 15 and $20^{\circ}C$ to $T_{50}$. K-based hydrogel-primed seeds with 70% DC showed the fastest germination among K-based hydrogels with various DC levels, but it took 0.6 days more to $T_{50}$ compared to Na 70%. The hydration rate (HR) of DW-primed seeds was 37% lower than that of Na 70%-primed seeds at $15^{\circ}C$ priming temperature, which indicates that Na 70% priming is the best solid matrix priming condition for promoting the germination of H. arenarius seeds.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.3
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• pp.137-145
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• 2009

As an efficient controlled release system for rhBMP-2, a functional nanoparticle-hydrogel complex, incorporated with matrix metalloproteinase(MMP) sensitive peptide cross-linker, was developed and used as a bone transplant. In vivo bone formation was evaluated by soft x-ray, histology, alkaline phosphatase(ALP) activity and mineral contents analysis, based on the rat calvarial critical size defect(8mm in diameter) model. Significantly, effective bone regeneration was achieved with the rhBMP-2 loaded MMP sensitive hyaluronic acid(HA) based hydrogel-Nanoparticles(NP) complex, as compared to only MMP HA, the MMP HA-NP without rhBMP-2, or even with the rhBMP-2. These improvements included the formation pattern of bone and functional marrow, the degree of calcium quantification, and the ALP activity. These results indicate that the MMP sensitive HA with nano-particle complex can be a promising candidate for a new bone defect replacement matrix, and an enhanced rhBMP-2 scaffold.

• Carbon letters
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• v.9 no.4
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• pp.283-288
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• 2008

The composites of temperature-sensitive hydrogel and activated carbons were prepared in order to improve both the mechanical strength of hydrogel matrix and the loading capacity of drug in a hydrogel drug delivery system. The swelling of composite hydrogel was varied depending on the temperature. Both the swelling and the release behavior of the composite hydrogel were varied depending on the kind of activated carbon. The release behavior showed the high efficiency which is important for practical applications.

• Macromolecular Research
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• v.14 no.4
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• pp.461-465
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• 2006

Two types of injectable system using thermosensitive chitosan (chitosan-g-NIPAAm), hydrogel and microparticles (MPs)-embedded hydrogel were developed as drug carriers for controlled release and their pharmaceutical potentials were investigated. 5-Fluorouracil (5-FU)-loaded, biodegradable PLGA MPs were prepared by a double emulsion method and then simply mixed with an aqueous solution of thermosensitive chitosan at room temperature. All 5-FU release rates from the hydrogel matrix were faster than bovine serum albumin (BSA), possibly due to the difference in the molecular weight of the drugs. The 5-FU release profile from MPs-embedded hydrogel was shown to reduce the burst effect and exhibit nearly zero-order release behavior from the beginning of each initial stage. Thus, these MPs-embedded hydrogels, as well as thermosensitive chitosan hydrogel, have promising potential as an injectable drug carrier for pharmaceutical applications.

• Macromolecular Research
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• v.12 no.5
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• pp.507-511
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• 2004

We have developed an injectable thermosensitive hydrogel for local drug delivery to treat cancers clinically. We selected chitosan as a polymer matrix because of its biocompatibility and biodegradability. Glycerol 2-phosphate disodium salt hydrate (${\beta}$-GP) was used to neutralize the chitosan solution to physiological pH. The chitosan solution displayed a sol-gel phase transition in a pH-and temperature-dependent manner and formed an endothermic hydrogel after subcutaneous injection into mouse in the presence of ${\beta}$-GP. Additionally, we evaluated the biodegradation of chitosan hydrogel in mice by measuring the volume of injected chitosan hydrogel after subcutaneous injection. The injected chitosan hydrogel in mice was sected and stained with hematoxylin-eosin reagent for histological observation to confirm biodegradation of the hydrogel by the infiltrated cells. Chitosan hydrogel systems that possess biocompatibility and biodegradability could be promising thermosensitive injectable materials useful as depot systems for local anti-cancer drug delivery.