• Corrosion Science and Technology
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• 제15권5호
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• pp.209-216
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• 2016

In the present study, chitosan based self-healing anticorrosion coatings were prepared by layer by layer (lbl) addition of chitosan (Ch) and polyvinyl butyral (PVB) on mild carbon steel substrate. Chitosan coatings exhibited enhanced coating stability and corrosion resistance in aggressive environments by the application of a PVB top layer. Chitosan layer in the lbl coatings have been modified by using glutaraldehyde (Glu) and silica ($SiO_2$). Performance of different coatings was tested using electrochemical impedance spectroscopy and immersion test. The best anticorrosion performance was observed in case of 10 % Ch_$SiO_2$_PVB coatings, which withstand immersion test over 25 days in 0.5 M salt solution without visible corrosion. 10 % Ch_$SiO_2$ coatings without the PVB top layer didn't last more than 3days. Application of PVB top layer sealed the defects in the chitosan pre-layer and improved its hydrophobic nature as well. Raman spectra and SEM of steel surfaces after corrosion study and removal of PVB_Ch/Glu_PVB coatings showed a passive layer of iron oxide, attributing to the self-healing nature of these coatings. Conducting particle like graphene reinforcement of chitosan in the lbl coatings enhanced corrosion resistance of chitosan coatings.

• Journal of Magnetics
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• 제14권3호
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• pp.124-128
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• 2009

Magnetic nanoparticles were synthesized by using the sonochemical method with oleic acid as a surfactant. The average size of the magnetite nanoparticles was controlled by varying the ratio R=[$H_2O$]/[surfactant] in the range of 2 to 9 nm. To prepare chitosan-coated magnetite nanoparticles, chitosan solution was added to a magnetite colloid suspension under ultrasonication at room temperature for 20 min. The chitosan-coated magnetite nanoparticles were characterized by several techniques. Atomic force microscopy (AFM) was used to image the chitosan-coated nanoparticles. Magnetic hysteresis measurement was performed by using a superconducting quantum interference device (SQUID) magnetometer to investigate the magnetic properties of the magnetite nanoparticles and the chitosan-coated magnetite nanoparticles. The SQUID measurements revealed the superparamagnetism of both nanoparticles. The T1- and T2-weighted MR images of these chitosan-coated magnetite colloidal suspensions were obtained with a 4.7 T magnetic resonance imaging (MRI) system. The chitosancoated magnetite colloidal suspensions exhibited enhanced MRI contrasts in vitro.

• Fisheries and Aquatic Sciences
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• 제25권2호
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• pp.64-75
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• 2022

This study aimed to investigate the effect of different coating materials on the quality of shrimp (Litopenaeus vannamei) during chilled storage for 10 days. Fresh shrimp were randomly divided into five groups: the control group, the hypotaurine treatment group (2%), the chitosan group (1%), the hypotaurine + chitosan group (2% hypotaurine solution with 1% of chitosan), and the sodium metabisulfite treatment group (1.25%). Compared with other treatments, the lower accumulation of total visible counts (TVC, 5.25 Log₁₀ CFU/g), total volatile basic nitrogen (TVB-N, 22.5 mg/100 g) and thiobarbituric acid values (TBA, 0.58 mg MDA/kg) suggested that coating of chitosan-hypotaurine could retard the microbial activity, protein degradation and lipid oxidation of shrimp. Meanwhile, results demonstrated that the chitosan coating combined with hypotaurine showed an excellent performance in inhibiting quality deterioration (pH 7.5, ∆E 7.0, hardness 393 g, and elasticity 0.69). Furthermore, the melanosis degree of shrimp was alleviated, and the sensory parameters, including appearance, odor and texture, were maintained to the acceptable level by chitosan based hypotaurine treatment during the chilled storage.

• 한국식품과학회지
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• 제30권4호
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• pp.817-822
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• 1998

키토산 분해효소 활성이 높은 미생물로 Aspergillus oryzae ATCC 22787를 탐색해 내었으며, 이 균주를 키토산 0.5%, yeast extract 0.5% 조성의 배지에 배양하여 효소를 생산하였다. 고분자 키토산은 효소분해가 진행되어 감에 따라 항균력이 증가하였는데, 2%용액의 점도가 $10{\sim}5{\;}cp{\;}(30^{\circ}C)$에서 균 증식 억제력이 가장 강하게 나타나 고분자 키토산에 비해 약 40배 가량 항균력이 증가하였다. 또한 키토산용액 특유의 떫은 맛도 키토산이 저분자화되어감에 따라 현저하게 감소되었다. 그러나 점도 4.0 cp 이하의 극히 저분자의 키토산은 항균력이 오히려 소실되었다. 효소분해물을 0.3% 첨가한 제품은 pH 7.0, 0.5% 첨가 제품은 pH 6.9로서 무첨가 제품의 pH 7.4 보다는 약간 낮았다. 효소분해물의 첨가로 제품의 색상은 약간 황색화되었으나 0.3% 정도의 첨가로는 별 문제가 없었다. 탄력은 조금 향상되었고, 맛에도 문제가 없었다. 어묵에 효소분해물을 0.3% 첨가하고 $30^{\circ}C$에서 저장하였을 때 저장기한이 무첨가구에 비해 2일 연장되었고, $20^{\circ}C$ 저장시에는 4일, $15^{\circ}C$ 저장시에는 6일 가량 연장되는 효과가 나타났다.

• Advances in materials Research
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• 제9권3호
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• pp.233-250
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• 2020

In this study, a chitosan based coating method was developed and applied on the shoe lining leather surface for evaluating its inhibition to bacterial and fungal attacks. At first, chitosan was prepared from raw prawn shells and then the prepared chitosan solution was applied onto the leather surface. Secondly, the characterization of the prepared chitosan and chitosan treated leather was performed by solubility test, ATR-FTIR, XRD pattern, SEM and TGA. Evaluation of antimicrobial efficacy of chitosan was assessed against two gram positive, two gram negative bacteria and a reputed fungi by agar diffusion test. The results of this study demonstrated that chitosan took place in both the surface of collagen fibres and inside the collagen matrix of crust leather. The chitosan showed strong antimicrobial activities against all the tested microorganisms and the inhibition increased with increasing percentage of chitosan. Therefore, the prepared chitosan in this study can be an environment friendly biocide, which functions simultaneously against different spoilage bacteria and fungi on the finished leather surface. Thus by using the prepared chitosan in shoe lining leather, the possibility of microbial attack during shoe wearing can be minimized which is one of the important hygienic requirements of footwear.

• 한국미생물·생명공학회지
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• 제22권6호
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• pp.643-645
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• 1994

Chitin and chitosan has been almost neglected until 1960s, although they are the second largest biomass on earth. Their major use were as a natural flocculant for waste-water treatment, and partially used in the areas of food, feed industry, cosmetics and medicine. Possible sources of chitin among biomass were tested, and antibacterial activity and viscosity-concentration relation- ship of diluted acidic solution were examined.

• 한국포장학회지
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• 제8권2호
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• pp.18-26
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• 2002

Films of methylcellulose(MC), chitosan and their blends were prepared using water and acid solution as a solvent. The transition behavior and miscibility of polymers and their blends were characterized by dynamic mechanical analysis(DMA) and thermogravimetric analysis(TGA). The DMA analysis of PEG400/MC blends has shown that PEG400 was compatible with MC and was effective plasticizer since the curves of $tan{\delta}$ against temperature exhibited single peak, corresponding to single glass transition temperature, which were displaced to lower values with increasing PEG400 content. Results of DMA analysis and TGA analysis of MC/chitosan blends indicate that there are some miscibility between MC and chitosan in the blends, attributed to the similarities between two polysaccharides and interactions of two polymers in the blends. The inclusion of PEG400 in the blends increase the miscibility between two components in the blends.

• Journal of Microbiology and Biotechnology
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• 제11권3호
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• pp.423-427
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• 2001

Chitosan/alginate capsules were formed by electrostatic interactions and had appropriated mechanical strength, permeability to albumin, and stability to hepatocytes. Rat hepatocytes were isolated and immobilized in chitosan/alginate capsules. During the encapsulation process with hepatocyte, 10% of viability was decreased mainly due to the low pH of the chitosan solution. Among various capsule fabrication methods, the chitosan-alginate capsule showed the highest mechanical strength. Addition of collagen in the capsule with hepatocytes enhanced hepatic metabolism as well as the cell viability for 2 weeks of culture. The hepatocyte in the capsule without collagen decreased the viability to 10% for 2-week cultures.

• Food Science and Biotechnology
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• 제15권6호
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• pp.925-930
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• 2006

Chitosan-based nanocomposite films were prepared using a solution intercalation method incorporating varying amounts of organically modified montmorillonite (Cloisite 30B) from 0 to 30 wt%. The nanocomposite films prepared were optically clear despite a slight decrease in the transmittance due to the spatial distribution of nanoclay. X-ray diffraction patterns indicated that a certain degree of intercalation or exfoliation formed when the amount of clay in the film was low and that microscale tactoids formed when the clay content in the sample was high (more than 10 wt%). The tensile strength (TS) of the chitosan film increased when the clay was incorporated up to 10 wt% and then decreased with further increases in the clay content of the film. The elongation at break (E) increased slightly upon the addition of low levels of clay up to 5 wt% and then decreased with further increases in the amount of the clay in the film. The water vapor permeability (WVP) decreased exponentially with increasing clay content. The water solubility (WS) and swelling ratio (SR) of the nanocomposite films decreased slightly, indicating that the water resistance of the chitosan film increased due to the incorporation of the nanoclay.

• 한국식품영양과학회지
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• 제26권5호
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• pp.807-813
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• 1997

Various additives(glucono-$\delta$-lactone, glycine, chitosan, Chinese pepper extract+msutard oil, cinnamon oil+ginger oil+mustard oil, Chinese pepper extract), used in the Korean patents singularly or in combination, were tested for extension of shelf-life of kimchi. Addition of glucono-$\delta$-lactone or chitosan was somewhat effective in delaying the fermentation rate, however no such effect was seen by other additives. Chitosan at the concentrations of 0.5, 1.0, and 1.5% was similarily effective in delaying the fermen-tation rate. Mustard oil or cinnamon oil tend to delay the fermentation rate by singular addition at the concern tration of 0.5% or 1%. Soaking of the salted and washed Chinese cabbage in 0.5% chitosan solution resulted in delay of the fermentation rate of kimchi.