• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.475-479
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• 2011

Chitosan is a natural polymer that has many physicochemical(polycationic, reactive OH and $NH_2$ groups) and biological(bioactive, biocompatible, and biodegradable) properties. In this study, chitosan nanoparticles were prepared using poly-${\gamma}$-glutamic acid(${\gamma}$-PGA) as gelling agent. Nanoparticles were formed by ionic interaction between carboxylic groups in ${\gamma}$-PGA and amino groups in chitosan. Chitosan(0.1~1 g) was dissolved in 100 ml of acetic acid (1% v/v) at room temperature and stirred overnight to ensure a complete solubility. An amount of 0.1 g of ${\gamma}$-PGA was dissolved in 90 ml of distilled water at room temperature. Chitosan solution was dropped through needle into beaker containing ${\gamma}$-PGA solution under gentle stirring at room temperature. The average particle sizes were in the range of 80~300 nm. The prepared chitosan/${\gamma}$-PGA nanoparticles were used to examine their removal of several heavy metal ions($Cd^{2+}$, $Pb^{2+}$, $Zn^{2+}$, $Cu^{2+}$, and $Ni^{2+}$) as adsorbents in aqueous solution. The heavy metal removal capacity of the nanoparticles was in the order of $Cu^{2+}$ > $Pb^{2+}$ > $Cd^{2+}$ > $Ni^{2+}$ > $Zn^{2+}$.

• Journal of Veterinary Clinics
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• v.29 no.4
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• pp.283-296
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• 2012

Allergic contact dermatitis (ACD) is an inflammatory skin disease and regarded as a prototype of T-cell mediated delayed-type hypersensitivity reactions. Poly-${\gamma}$-glutamic acid (PGA) is a biodegradable polymer that is produced by Bacillus subtilis. This study was performed to assess the effects of PGA in a canine model of ACD. ACD was induced on the back of dogs induced by sensitization and repeated application by 2,4-dinitro-1-chlorobenzene (DNCB). Topical treatment of PGA was applied once a day for 12 days and skin biophysical parameters including transepidermal water loss (TEWL), skin hydration, skin pH, skin thickness and erythema index, were measured every two days during experimental periods. Histopathology and immunohistochemistry were performed to evaluate the antiinflammatory effect. In skin biophysical parameters, TEWL, skin hydration, skin thickness and erythema index were significantly increased, with a maximum increase appeared on day 2 (p < 0.05). On the other hand, skin pH was significantly decreased, with a maximum decrease appeared on day 2 (p < 0.01). After the completion of PGA treatment, skin biophysical parameters were significantly reached those of baseline in a time-dependent manner (p < 0.05). In histopathology, marked increases of epidermal thicknesses were induced after DNCB challenge with numerous inflammatory cell infiltrations and edematous changes, decreases of connective tissue occupied regions in dermis. In addition, marked increases of cytokine - tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and interferon-${\gamma}$ (IFN-${\gamma}$)-immunoreactivities in the dermis and of apoptotic markers - caspase-3 and PARP-immunoreactivities in the epidermis were observed in DNCB-PBS control as compared with intact control, respectively (p < 0.01). It means, the ACD and related apoptotic changes were induced by DNCB in the present study. However, these ACD induced by DNCB and related apoptosis in epidermis were significantly inhibited by treatment of PGA treated skin, the decreases of infiltrated inflammatory cells and related decreases of pro-inflammatory cytokine immunoreactivities were also observed (p < 0.01). Based on these findings, PGA may have anti-inflammatory and alleviatory effects in the allergic contact dermatitis.

• Bioindustry News
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• v.21 no.2
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• pp.12-14
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• 2008

• Food preservation and processing industry
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• v.6 no.1
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• pp.8-15
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• 2007

• Polymer Science and Technology
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• v.20 no.5
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• pp.440-446
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• 2009

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.35-41
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• 2014

Poly(g-glutamic acid) (g-PGA) is a very promising biodegradable polymer that is produced by microorganism of Bacillus subtilis. Because g-PGA is water-soluble, anionic, biodegradable, and even edible, its potential applications have been studied from an industrial standpoint. In this study, we fabricated porous g-PGA foams by means of a freeze-solvent extraction method for tissue-engineering applications. Porous g-PGA foams were chemically cross-linked using a hexamethylene diisocyanate solution. An aqueous basic solution was used to neutralize g-PGA foam for cell culturing. During an in vitro cell culture study, it was observed that primary rabbit ear chondrocytes were well at tached and spread over the surface oft hree-dimensional cross-linkedg-PGA foam. From these results, it is concluded that cross-linkedg-PGA foam is aprom is in gmaterial for tissue-engineering applications, especially those pertaining to the regeneration of human cartilage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.12
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• pp.645-651
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• 2015

This paper presents an experimental study on the freeze drying process for poly ${\gamma}$ glutamic acid. The physical properties of poly ${\gamma}$ glutamic acid are measured during the freeze-drying process. The moisture contents of poly ${\gamma}$ glutamic acid according to the glass transient temperature are obtained by DSC (Differential Scanning Calorimetry) analysis. The end point of primary drying for the poly ${\gamma}$ glutamic acid with a thickness of 3 mm is obtained by measuring the thickness of the dried layer, the amount of moisture evaporation, the moisture content, and the pressure in the drying vacuum chamber during the freeze-drying process. By considering the variation in the glass transient temperature with respect to the moisture content of the material, a control schedule for the heating plate temperature is suggested during the secondary drying process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.11
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• pp.1544-1551
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• 2016

Various types of fermented soybean foods are consumed in various Asian countries, including China, Indonesia, Japan, Korea, and Vietnam. Cheonggukjang is a Korean whole soybean paste fermented by Bacillus subtilis and regarded as a healthy food. The objective of this study was to investigate the Ca-bioavailability and anti-osteoporotic effects of cheonggukjang (CGJ) containing high poly-gamma glutamate (PGA) contents in an animal model. Blood samples were collected from the jugular vein at 0, 0.5, 1, 2, 3, 4, and 5 h after a single oral dose in male rats. Ca-bioavailability in CGJ containing high PGA contents was approximately 3~5 times higher than that of natural CGJ. Female rats were either sham-operated (sham; n=5) or surgically ovariectomized (OVX; five animals per group) and then administered to OVX control, raloxifene hydrochloride (RLX) 1 mg/kg/d, or CGJ containing high contents of PGA (20 and 200 mg/kg/d) for 12 weeks. Serum osteocalcin concentration was significantly lower in the CGJ 200 mg/kg/d group compared with the OVX control group. Serum progesterone concentration was significantly higher in the CGJ 200 mg/kg/d group compared with the OVX control group. Reduction grade of the trabecular bone decreased in the RLX 1 and CGJ 200 mg/kg/d group compared with that of the OVX control group. In conclusion, CGJ 200 mg/kg/d may have inhibitory effects on osteoporosis in OVX rats, and Ca-bioavailability was improved in CGJ containing high PGA contents.

• Journal of Life Science
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• v.16 no.2 s.75
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• pp.175-179
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• 2006

A bacterium that produced a large amount of poly-$\gamma$-glutamate (PGA) was isolated from the compost and designated as Bacillus subtilis CH-10. The optimum temperature and pH for PGA production were at $37^{\circ}C$ and 7.5, respectively. The maximum amount of PGA production (18.84 mg/ml) was obtained when it was grown in a medium containing 3% L-glutamate and 5% sucrose at $37^{\circ}C$ with shaking. The result that the L-glutamate significantly induced PGA production indicates that it produces a PGA by the glutamate dependent manner. Some properties of the PGA obtained at different times of cultivation were investigated by SDS-PAGE and ninhydrin analysis. The PGA production was elongated along with cultivation time and maximum amount was achieved at 96 h. Average molecular weight of PGA was estimated to be 1100 kDa by FDNB method.

• Polymer(Korea)
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• v.33 no.5
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• pp.501-508
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• 2009

The thermal degradation experiment of sodium salt of poly (${\gamma}$-glutamic acid) (PGGNa) has been carried out in both its solid phase and solution phase at the range of $57{\sim}120^{\circ}C$ and their molecular weight decreasing effect was analyzed as a function of time by means of viscometry and light scattering. Based on the solid phase degradation results, it was supposed that the bond scission rate in a polymer chain kept constant and that the bond scission was occurred on a randomly located position in a polymer chain. For the degradation in solution phase, it was also found that all data at various temperatures were dropped on a single master curve when the reduced time $t/t^*$ was used in the plot of the reciprocal intrinsic viscosity (or molecular weight). This degradation curve in solution phase could be expressed as the sum of a single exponential and a linear equation and especially, the single exponential character appeared only at the beginning stage. The activation energy was measured as $107{\sim}115$ kJ/mol in this study and agreed with the literature values.