• 한국의류학회지
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• 제20권4호
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• pp.682-689
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• 1996

A preparative method has been proposed for obtaining chitosan products which have a desired degree of deacetylation (DD, %) without much decrease in molecular weight. Deacetylation was prepared by two methods. The method I which was proposed by Domard etc. was that DMSO/thiophenol was used repeatedly only during the deacetylation, the method II was that DMSO/thiophenol was used after the alkali treatment. Then, effective deacetylation was performed by the method ll. To determine the degree of deacetylation, potentiometric titration method was adopted. According to the increase of DD, the viscosity average moleclar weght $(\overline{M\upsilon}$) and the DP of the chitosan products were decreased. The intensity of FT-lR peak appeared at $1655cm^{-1}, which was characteristic peak of amide I (Nacetyl secondary amide group), was gradually decreased with deacetylation. X-ray analysis showed that the lattice-spacing in the chitosan film increased with the degree of deacetylation, but the difference of the transparency of the chitosan products was not diverged significantly.

• 한국수산과학회지
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• 제28권4호
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• pp.392-396
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• 1995

Chitosan의 탈아세틸화도와 분자량에 미치는 chitosan 제조조건의 영향을 조사한 결과는 다음과 같다. 탈아세틸화 과정에서 NaOH 농도가 높을수록 탈아세틸화는 많이 일어났으나 $40\%$ 이상의 농도에서는 농도가 증가할수록 탈아세틸화의 증가폭은 감소하고, 분자량의 감소폭은 줄어들지 않았다. 가열온도를 $130^{\circ}C$ 에서 $150^{\circ}C$로 증가시켰을 때 탈아세틸화도는 $84\%$에서 $87\%$로 $3\%$ 정도 증가한 반면 분자량은 267,000에서 85,800로 $90^{\circ}C$에서 $130^{\circ}C$로 증가하였을 때의 분자량 감소폭보다 크게 나타났다. 그리고 3시간 이상 연속 알칼리처리하여도 $86\%$ 이상의 탈아세틸화도를 얻지 못하였지만 간헐적으로 수세하여 처리한 경우 3회 처리하였을 때 $93\%$의 탈아세틸화가 일어났다. 연속으로 3시간 처리했을 경우 탈아세틸화도는 $84\%$이었고, 분자량은 267,000이었으나 간헐반복처리로 3시간처리 했을 때는 탈아세틸화도가 $93\%$, 분자량은 280,000으로 연속처리 한 경우보다 더 높았다.

• 한국의류산업학회지
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• 제8권4호
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• pp.458-464
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• 2006

The adsorption ability of heavy metal ions from the aqueous solution by chitosan, which it is well known natural biopolymer, has been investigated. The fundamental study in this research is focusing on the physicochemical adsorption utilizing the chitosan as a organic chelating adsorbent, adsorb especially heavy metal ions from the waste liquid solution. The adsorption ability of the chitosan between metal ions, having different characteristics with Mw of 188,600, 297,200, and 504,200 g/mol and degree of deacetylation (DD) of 86.92% and 100% were investigated targeting on the $Ni^{2+}$, $Co^{2+}$, $Zn^{2+}$, and $Pb^{2+}$ ions, respectively. The uptake of heavy metal ions with chitosan was performed by atomic absorption flame emission spectrophotometer (AAS) as conducted residual metal ions. It was found that chitosan has an strong adsorption capacity for some metals under certain conditions. Chitosan, which have 100% degree of deacetylation showed high adsorption recovery ratio and have an affinity for all kinds of heavy metals. In contrast, the molecular weight of chitosan was not completely affected on metal ion adsorption.

• 한국의류산업학회지
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• 제5권1호
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• pp.71-76
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• 2003

Three different types of chitosan were prepared from red crab shells to study anti-microbial activity of chitosan on pathogenic bacteria, MRSA(Methicillin-resistant. Staphylococcus aureus), Water-insoluble chitosan, whose degree of deacetylation is kept over 90% and molecular weights are 20,000, 500,000, 150,000, 80,000, and 40,000, respectively. Water-soluble chitosan, whose degree of deacetylation is about 48% and molecular weights are 200,000 and 80,000. Water-soluble chitosan, whose degree of deacetylation is 82% and molecular weight is 3,900. The anti-microbial activities of three types of chitosan were investigated by Tube Dilution Technique(TDT) and Agar Plate Smear Method(APSM). And the following conclusions are made ; Chitosan having 5 different types of M.W chitosan (over 90% deacetylation) showed similar anti-microbial activities at over 0.05% concentration. Especially, chitosan having M.W 40,000 150,000 showed the excellent anti-microbial activity. The anti-microbial activity of chitosan was enhanced when the chitosan/acetic add solution was aged for 7days. The anti-microbial activity of chitosan was only shown at chitosan/acetic acid solution. The anti-microbial activity was not detected in chitosan solution dissolved in neutral pH water. Therefore, it can be concluded that the anti-microbial activity was due to NH3+ cationic ion of chitosan in acidic aqueous solution.

• 한국의류산업학회지
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• 제5권5호
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• pp.529-538
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• 2003

Chitosan should be satisfied a certain Mw range for the final application, Low molecular weight chitosan(LMWC) can be acquired by depolymerizing high molecular weight starting chitosan. Using $H_2O_2$ in depolymerizing chitosan is very effective and reproducible in controlling Mw of resulting LMWC. However, $H_2O_2$ can break glycoside linkage of chitosan and oxidize some $-NH_2$ groups in chitosan. It has been reported that decrease in DA(degree of deacetylation) of LMWC prepared by $H_2O_2$. However, any quantitative data of decrease in DA has not been reported yet. In this study, DA of initial chitosan and DA of $H_2O_2$ treated chitosan were measured and the change in DA of chitosan upon $H_2O_2$ treatment were investigated. Change in DA was very different upon $H_2O_2$ treatment condition. LMWC also showed DA change upon time passage. Pre-swelling treatment of initial chitosan and low ratio of $H_2O_2$/chitosan prevented a decrease in DA significantly. Yellowing of LMWC was detected upon time passage, however, decrease in DA was minimal (around 1%).

• 한국환경보건학회지
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• 제27권1호
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• pp.36-43
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• 2001

Chitosans were prepared from red crab chitin under various alkali treatment conditions(different alkali concentrations, reaction times and temperatures) and theirphysicochemical properties were investigated. The nitrogen content and deacetylation degree of red crab chitin were 6.15% and 22.17A%, respectively. By the IR spectra, red crab and reference chitin showed the sharp bands at 1650 $cm^{-1}$ / and 1550 $cm^{-1}$ /, which are characteristic of chitin. The nitrogen contents of prepared chitosans ranged from 6.19~7.48%. Thedeacetylation degree was increased from 63~76% and 48~78% with increasing reaction time and temperature, whereas viscosity was decreased. The nitrogen content and yield of red crab chitosan perpared from chitin with 50% NaOH, 1:25(w/v) for 3.0 hr at 120$cm^{-1}$ / were 7.26% and 85.0%, respectively. and viscosity, deacetylation degree and molecular weight, 67.0 mPa.s, 75.0% and 6.5$\times$10$^{5}$ Dalton, respectively. From the IR spectra, the amide absorption bands of red crab and reference chitosan became very weak, similarly. And at solid state $^{13}$ C-NMR spectra, C=O(carbonyl carbon) signals absent, whereas $CH_3$(methyl carbon) was residues. Chemical shift of $^{13}$ C-NMR spectra of red crab and reference chitosans were in good agreement with slight experimental deviation.

• 한국식품과학회지
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• 제31권2호
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• pp.558-563
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• 1999

반응표면분석에 의하여 chitosan 제조조건에 따른 chtosan의 이화학적 특성을 모니터링하였다. 탈아세틸화도는 NaOH 농도가 증가함에 따라 급격히 감소하였다. Chitosan의 용해도는 NaOH 농도가 51%에서 가장 높았으며, 탈아세틸화 온도 및 시간은 각각 $109^{\circ}C$, 123분에서 가장 높았다. Chitosan의 점도에 대한 탈아세틸화 조건의 영향은 NaOH농도의 영향을 주로 받고 있었다. Chitin의 탈아세틸화에 따른 chitosan의 최적 제조조건범위는 NaOH 농도$(52{\sim}54%)$, 탈아세틸화 온도$(100{\sim}115^{\circ}C)$ 및 탈아세틸화 시간$(100{\sim}140\;min)$이었다.

• 한국의류학회지
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• 제28권6호
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• pp.807-818
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• 2004

The antibacterial activities of several types of chitosan were measured against Staphylococcus aureus and evaluated for their application to antibacterial textile finishing. The ％ reduction of bacteria of the chitosans prepared in our laboratory were between 72 and 87%. The two water-soluble chitosans with molecular weights 1,000 and 3,000 did not show antibacterial activities. The deacetylation of chitosan was appeared to increase antibacterial activity. The ％ reduction in bacterial density of the 86％-deacetylated chitosan solution was 56% where that of the 76％-deacetylated chitosan solution was only 17％ at 0.1% chitosan concentration. Molecular weights of the chitosans seemed not to affect antibacterial activities of chitosans. The antibacterial activity of the acid-soluble, 86%-deacetylated chitosan with 4 cps showed 98% of the ％ reduction at the level of 0.2％ chitosan. The ％ reduction of bacteria of this chitosan was higher at the higher concentration of acetic acid in the chitosan-bacterial mixture. The antibacterial activity was increased with the pH change over the range of 4.0 to 6.5. The 100% of the ％ reduction of bacteria was achieved within 4 hour incubation of the chitosan-bacterial mixture. According to the data obtained from the above experiments, the four chitosans among the six prepared in our laboratory were proved to be valuable for antibacterial textile finishing.

• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.26-31
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• 1999

The advantages of the organism Streptomycs griseus HUT 6037 is that the chitinase and chitosanase using chitinaceouse substrate are capable of hydrolyzing both amorphous and crystalline chitin and chitosan. We attempted to investigate the optimization of induction protocol for high-level production and secretion of chitosanase and the influence of chitin and partially deacetylated chitosan sources (75∼99% deacetylation). The maximum specific activity or chitinase has been found at 5 days cultivation with the 48 hours induction time using colloidal chitin as a carbon source. To investigate characteristic of chitosan activity according to substrate, we used chitosan with various degree of deacetylation as a carbon source and found that this strain accumulates chitosanase in the culture medium using chitosanaceous substrates rather than chitinaceous substrates. The highest chitosanase activity was also presented on 4 days with 99% deacetylated chitosan. The partially 53% deacetylated chitosan can secrete both chitinase and chitosanase which was defined as a soluble chitosan. The specific activities of chitinase and chitosanase were 0.89 at 3 days and 1.33 U/mg protein at 5 days, respectively. It indicate that chitosanase obtained from S. griseus HUT 6037 can hydrolyze GlcNAc-GlcN and GlcN-GlcN linkages by exo-splitting manner. This activity increased with increasing degree of deacetylation of chitosan. It is the first attempted to investigate the effects of chitosanase on various degrees of deacetylations of chitosan by S. griseus HUT 6037. The highest specific activity of chitosanase was obtained with 99% deacetylated chitosan.

• 한국가정과학회:학술대회논문집
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• 한국가정과학회 1997년도 가정과학회 총회 및 학술대회
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• pp.33-37
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• 1997

Cotton fabric was treated with chitosan solution by pad-dry(-cure) method to impart antimicrobial properties. Four chitosans of different degree of deacetylation(DAC: 65~95％) with similar molecular weight(ca. 50, 000) and one chitosan oligomer(MW 1, 800, DAC 86％) were used. Antimicribial activity against Staphylococcus aureus was evaluated by the Shake Flask Method. Treated fabrics were laundered up to 20 times according to AATCC Test Method 60-1986 and antimicrobial activity of laundered fabrics was evaluated. The antimicrobial activity was increased with the concentration and DAC of chitosan used. And the cured samples showed better durability to laundering than not-cured samples. Crosslinker and binder decreased the antimicrobial activity of fabrics treated with chitosan oligomer and were not effective to improve the durability to washing.