The purposes of this study are to develop a chitosan suspension for the carbon dioxide (CO2) concentration indication of packaged food and to investigate the changes in the CO2 indication corresponding to 2-amino-2-methylpropan- 1-ol (AMP) or 2-aminoethanol (monoethanolamine, MEA) addition. Chitosan suspension was prepared by adding chitosan (0.1, 0.2, and 0.4%) to distilled water and subsequently the pH of the suspension was adjusted to 7.0 after the addition of AMP or MEA. Changes in the pH and the turbidity of the chitosan suspension were measured over time under exposure in a normal atmosphere or 100% carbon dioxide environment. The pH of the chitosan suspension exposed at 100% carbon dioxide environment decreased rapidly up to approximately 6.3 in the initial CO2 exposure. The transmittance values of 0.1 and 0.2% chitosan suspensions with 5% AMP increased from 32 to 99% and from 19 to 86%, respectively. The addition of 5% AMP improved the visual indication performance of the chitosan suspension since it increased significantly the width of the transmittance value before and after CO2 exposure. The chitosan suspension with AMP has a potential to be used as a quality indicator of the packaged foods which produce carbon dioxide during storage and distribution.

Poly(ether-block-amide)(PEBA, PEBAX)는 열가소성 탄성체로서 단단하고 견고한 성질과 부드럽고 유연한 성질을 동시에 지니고 있기 때문에 분리 막 이용 시 우수한 기계적 특성, 선택도, 높은 투과도를 제공할 수 있다. Chitosan은 갑 각류에서 얻을 수 있는 친환경적인 고분자 물질이나 Chitosan을 분리 막 이용시 낮은 기계적 안정성, 열적 안정성, gas barrier 성질들로 인해 이용하는데 한계가 있다. NaY Zeolite 친수성이 강한 가장 대표적인 제올라이트로서 강한 친수성과 분자체 효과에 의한 기체 투과 특성을 제공한다. 본 실험에서는 PEBAX와 Chitosan에 NaY Zeolite를 첨가하여 복합 막을 제조 하고 물리화학적 특성을 알아보았다. 기체 투과 실험은 국산 Sepra Tek사재 VPA-601을 사용하여 측정하였다. 기체투과실험은 일정압력의 조건에서 온도별, 고분자의 함량별로 행하였다.

항균 물질인 로즈마리 오일(RO), 자몽종자 추출물(GSE), 오레가노 오일(OO)을 각각 키토산 에멀젼에 혼입하여 코 팅제를 개발하였으며, 개발된 키토산 코팅제를 방울토마토에 적용하여 방울 토마토 위해 미생물의 저해 효과를 연구 하였다. 1%(v/v) 빙초산 수용액에 키토산 1%(w/v)을 첨가하여 교반한 후 0.50, 0.75, 1.00%(w/v) 농도의 RO, GSE, OO와 RO, GSE, OO 대비 25%(w/w) Tween-80을 혼합하여 10,000 rpm에서 2분간 균질화 한 뒤, 진공 펌프로 에멀젼 내 가스를 제거하여 코팅제를 개발하였다. 개발된 코팅제를 이용하여 방울토마토를 코팅한 후 살모넬라 혼합균주(S. Typhimurium, S. Montevideo, and S. Enteritidis)를 접종하여 살모넬라균의 저해 효과를 확인하였다. 농도가 각각 0.50, 0.75, 1%인 RO, GSE, OO를 혼입한 키토산 에멀젼 코팅제는 방울토마토에 접종된 살모넬라 혼합균주를 각각 0.7-1.1, 1.0-1.6, 그 리고 0.7-1.1 log CFU/cherry tomato를 저해하는 효과를 보였다. 본 연구를 통해 개발된 RO, GSE, 그리고 OO를 혼입한 키토산 코팅제는 방울토마토의 식중독 위해 미생물인 살모넬라균에 대한 저해 활성을 보였고 향후, 방울토마토의 미 생물학적 안전성과 저장성 향상에 기여하는 코팅제로서의 이용 가능성을 확인해주었다.

본 연구는 수확 후 감귤의 부패과 발생 억제를 위하여 grapefruit seed extract과 oregano oil이 혼입된 carnauba 코팅 과 calcium oxide이 혼입된 chitosan 코팅을 감귤에 적용하여 Penicillium italicium 저해 효과에 대하여 연구하였다. carnauba 수용액(18%(w/w))에 grapefruit seed extract 또는 oregano oil을 단독으로 각각 0.3-1%(w/w) 첨가하였고, grapefruit seed extract과 oregano oil을 0.75:0.25, 0.5:0.5,그리고 0.25:0.75(w/w)의 비율로 혼합하여 첨가하였다. 또한 1% chitosan 수용 액의 경우 0.3-3%(w/w)의 calcium oxide을 첨가하여 코팅제를 개발하였다. 감귤 과피에 접종된 P. italicium에 대한 각 코팅제의 저해 효과는 부패과 발생률(%)로 표현하였다. carnauba wax 코팅의 경우, grapefruit seed extract을 단독으로 1% (w/w) 첨가, grapefruit seed extract과 oregano oil을 혼합하여 0.5:0.5%(w/w) 비율로 첨가하였을 때 부패과 발생률은 각각 23.6%와 25%로 유의적으로 가장 낮았고(P<0.05), calcium oxide을 첨가한 chitosan 코팅의 경우 calcium oxide의 농도와 관계없이 모든 조건에서 부패과 발생률이 유의적 차이를 보이지 않았다(P>0.05). 따라서 grapefruit seed extract 과 oregano oil이 혼입된 carnauba wax 코팅은 감귤의 저장 중 부패에 관여하는 P. italicium를 저해하여 저장성을 향상 시킬 수 있는 것으로 사료되었다.

The objective of this study was to evaluate size-different chitosan nanoparticles as a CO2 indicator. CO2 gas is dissolved to form H2CO3 which makes the solution acidic. Chitosan is acid soluble and its appearance (turbidity) changes depending on pH in aqueous solution. Two size-different chitosan nanoparticles were fabricated by ionic gelation between chitosan (0.30 and 0.50%, w/v) and 0.07% sodium tripolyphosphate (TPP) solution. The sizes of chitosan nanoparticles were 630.77 and 1194.87 nm, respectively. To investigate the effect of chitosan nanoparticles as CO2 indicator, the initial pH of chitosan nanoparticle suspension was adjusted to 8.0. Thereafter, 100% CO2 gas was injected into the chitosan nanoparticle suspension, and the changes of pH and absorbance (600 nm of absorption wavelength) of the suspension over time were measured for 28 min. Absorbance at the appearance transition and its corresponding time was calculated using logistic function (R2> 0.99).As a result, pH of chitosan nanoparticle suspension decreased rapidly under CO2 gas injection for 10 min and finally reached around 6.0. In addition, there was significant difference in appearance transition time which was6.62 and 12.45 min for small- and large-sized chitosan nanoparticle suspensions, respectively. This study suggests that chitosan nanoparticle suspension might be useful as a food quality indicator for CO2 emitting foods such as fermented foods.

Recently, with continuous developments in the field of materials science, graphene oxide (GO) has emerged as a promising material with excellent electrical, thermal, mechanical, and optical properties, which play important roles in most fields. Researchers have achieved considerable progress with graphene. Chitosan (CS) is a natural polymer that has been studied intensively owing to its specific formation, high chemical resistance, and excellent physical properties. These outstanding properties have led to its universal use in applications such as textile fabrics, tissue engineering, medicine and health, coatings, and paints. By combining the advantages of GO and CS, different types of promising materials can be obtained. This review discusses the preparation of GO-CS fibers, hydrogel and aerogel, and the applications of GO-CS nanocomposites. In addition, directions for future research on graphene material composites are discussed.

Poly(ether-block-amide)(PEBA, PEBAX)는 열가소성 탄성체로서 분리 막 소재로 이용할 경우 우수한 기계적 특성, 선택도, 높은 투과도를 제공할 수 있을 것으로 기대된다. Chitosan은 키틴에서 탈 아세틸화하여 얻은 불용성 고분자 물질로 Chitosan을 넣은 고분자막은 CO2의 막 투과도가 높아지는 특징이 있다. 본 실험에서는 복합 막을 제조하고 물리화학적 특성을 IR, XRD, TGA, SEM을 통하여 알아보았다. 기체 투과 실험은 국산 Sepra Tek사재 VPA-601을 사용하여 측정하였다. 기체투과실험은 3bar의 조건에서 온도별, 첨가된 고분자의 함량별로 행하였다.

This study was conducted to evaluate the accumulation and distribution of hydrophobically modified glycol chitosan (HGC) as a degradable nanoparticle in the body. To determine the movement of degradable HGC nanoparticles in the body, 20 mg/kg of lutetium177-labeled HGC (Lu177-HGC) with the size ranging from 320 to 400 nm was injected intravenously into ICR mice, and the amount of radioactivity remaining in blood and several organs was measured at various time points during the period of 5 days. In the pharmacokinetics analysis using the Lu177 radioisotope, the free Lu177 was mainly distributed and accumulated in the order of kidney>liver>lung at 1 day after the injection of the radioisotope. However, the Lu177-HGC showed a high distribution of nanoparticles in the order of liver>spleen>kidney during the experimental period of 5 days. These results would provide a basic pharmacokinetics for the use of HGC as a drug carrier in drug delivery system.

The ultimate goal of this study is to assess the accumulation and distribution of hydrophobically modified glycol chitosan (HGC) as a degradable nanoparticle in the body. To understand the movement of degradable nanoparticle HGC in the body, we intravenously injected a dose of 20 mg/kg of Cy5.5-labeled HGC with size ranging from 320 to 400 nm into ICR mice, and measured the amount of fluorescence remaining in blood and several organs at various time intervals. In blood, the level of Cy5.5-labeled HGC was the highest at 15 min, then after 30 min it decreased rapidly and reached a plateau form 30 min to 28 days. In the tissue we confirmed the presence of nanoparticles at high levels in the order of kidney>liver>submandibular gland until 28 days after injection. However, we did not find the presence of the particles in the brain or testes. These results will provide basic information on HGC as a drug delivery agent.

In this study, we fabricated a novel micro porous hybrid scaffold of biphasic calcium phosphate (BCP) and a polylectrolyte complex (PEC) of chitosan (CS) and hyaluronic acid (HA). The fabrication process included loading of CS-HA PEC in a bare BCP scaffold followed by lypophilization. SEM observation and porosimetry revealed that the scaffold was full of micro and macro pores with total porosity of more than 60 % and pore size in the range of 20~200μm. The composite scaffold was mechanically stronger than the bare BCP scaffold and was significantly stronger than the CS-HA PEC polymer scaffold. Bone morphogenetic growth factor (BMP-2) was immobilized in CS-HA PEC in order to integrate the osteoinductive potentiality required for osteogenesis. The BCP frame, prepared by sponge replica, worked as a physical barrier that prolonged the BMP-2 release significantly. The preliminary biocompatibility data show improved biological performance of the BMP-2 immobilized hybrid scaffold in the presence of rabbit bone marrow stem cells (rBMSC).

Chitosan에 HNT (halloysite nanotube)의 함량을 0, 3, 5, 10 wt%로 가하여 chitosan-HNT 복합막을 제조하였다. 복합막의 구조는 FT-IR, XRD, TGA, SEM으로 알아보았다. 기체투과 실험은 30˚C, 4kg/cm2 조건에서 수행하였고, chitosan-HNT 복합막의 HNT 함량 변화에 따른 CO2와 CH4의 기체투과도와 선택도를 조사하였다. Chitosan-HNT 복합막의 기체 투과도는 HNT 함량이 3 wt%에서 가장 큰 값을 보였고, 그 이상의 함량에서는 감소하였다. 선택도(CO2/N2)는 0~10 wt% 범위에서 HNT 내의 OH기와 CO2 간의 친화력으로 인하여 증가하였고, 약 1.3~3.8의 값을 보였다.

고분자 PDMS에 chitosan을 0.02∼0.60 wt%까지 넣어 복합막을 제조하였고, SEM과 TGA에 의해서 막의 특성을조사하였다. 기체투과 실험은 30°C, 4 kg/cm2 조건에서 수행하였고, 복합막의 함량 변화에 따른 H2와 N2의 투과도와 선택도를 조사하였다. PDMS-chitosan 복합막의 H2와 N2 투과도는 chitosan 함량이 증가하면 0∼0.20 wt%까지는 증가하고 그 이상에서는 감소하였다. 그리고 선택도(H2/N2)는 0∼0.20 wt%까지는 감소하고 0.20∼0.60 wt% 범위에서는 증가하였다. PDMS 고분자에 chitosan이 도입되어졌을 때 PDMS의 열적 안정성이 향상되었고, chitosan 함량이 증가했을 때 복합막의 표면은 거칠어지고 홀이 생성되었다.

본 연구에서는 CCl4 존재하에서 Cl2(g) and ultra violet(200~300nm) 파장으로 maleic anhydride 와 Cl2(g)을 반응시켜 α,β-dichlorosuccinic acid 를 합성하였다. 그리고 두 번째 반응은 N-(α,β-dichloro)succinic acid 함유 glucosamine 유도체(I)를 합성하는 것으로 methanol 함유 2% acetic acid 용매 하에서 glucosamine과 과량의 α,β-dichlorosuccinic anhydride을 넣은 후 온도를 70℃로 올리면서 반응시켰다. 우리는 합성한 유기산 유도체들이 해태 김 재배와 피부미용에 주로 유용하게 활용할 것으로 본다.

Nanocomposite films were made by a simple solution casting method in which multi-walled carbon nanotubes (MWCNT) and magnetite nanoparticles (Fe3O4) were used as dopant materials to enhance the electrical conductivity of chitosan nanocomposite films. The films contained fixed CNT concentrations (5, 8, and 10 wt%) and varying Fe3O4 content. It was determined that a 1:1 ratio of CNT to Fe3O4 provided optimal conductivity according to dopant material loading. X-ray diffraction patterns for the nanocomposite films, were determined to investigate their chemical and phase composition, revealed that nanoparticle agglomeration occurred at high Fe3O4 loadings, which hindered the synergistic effect of the doping materials on the conductivity of the films.

Although there are a number of reports regarding the toxicity evaluation of inorganic nanoparticles, knowledge on biodegradable nanomaterials, which have always been considered safe, is still limited. For example, the toxicity of chitosan nanoparticles, one of the most widely used drug/gene delivery vehicles, is largely unknown. In this report, we examined the cytotoxic effects of chitosan nanoparticles on mouse embryos at the blastocyst stage and in vivo implantation by embryo transfer. Blastocysts treated with 250 nm chitosan nanoparticles exhibited significantly increased apoptosis and a corresponding decrease in total cell number, which was concentration‐dependent. Moreover, the TUNEL positive signal in the embryos exposed to chitosan nanoparticles showed an increased of the ICM and the implantation success rate was lower than that of their control counterparts. Our results collectively indicate that in vitro exposure to chitosan nanoparticles induces apoptosis and retards implantation development after transfer to host mice. The results collectively show that chitosan nanoparticles have the potential to induce embryo cytotoxicity. Further studies are required to establish effective protection strategies against the cytotoxic effects of these nanoparticles.

Chitosan is widely used in cosmetics and medical fields. Special emphasis has been put on the chemical modification of chitosan to explore its full potential. We have described the synthesis and biological activity of novel peptide amino acid derivatives. The polyamino acid derivatives were synthesized by introducing alkylamine functional group on chitosan at C-6. The poor aqueous solubility of chitosan derivatives hinder both pharmacological studies and pharmaceutical development. To make amino acid coupled chitosan derivatives with improved biological effect and solubility, some attempts have been taken to consist of amino peptide group like aspartic acid and phenylalanine-aspartic acid derivatives onto chitosan C-6. The resultingly substituted chitosan was characterized by solubility in various solvents. We measured chitosan derivatives with 1H-NMR and 13C-NMR. Also, We were investigated on the physical properties and biological activities of these products.

Fibrous chitosan membranes were fabricated as a substrate for skin applications using an electro-spinning process with different solvents and varying concentrations. Scanning electron microscopy (SEM) images confirmed that the formation of the chitosan fibrous membrane in trifluoroacetic acid was better than that in acetic acid. Fourier transform infrared spectroscopy showed that the chitosan fibers were cross-linked with glutaraldehyde, and that the cytotoxicity of the aldehyde groups was reduced by glycine and washing by NaOH and DI water. Chitosan cross-linked fibrous membranes were insoluble in water and could be washed thoroughly to wash away glycine and excess NaOH and prevent the infiltration of other water soluble bio-toxic agents using DI water. MTT assay method was employed to test the cytotoxicity of chitosan membranes during fabricating, treating and washing processes. After the dehydration of cell cultured chitosan membranes, cell attachment behavior on the material was evaluated using SEM method. Effect of the treatment processes on the biocompatibility of the chitosan membranes was shown by comparing of filopodium and lamellipodium of fibroblast cells on grown washed and unwashed chitosan fibrous membrane. The MTT assay and SEM morphology confirmed that the washed chitosan fibrous membrane increased cell attachment and cell growth, and decreased toxicity compared to results for the unwashed chitosan fibrous membrane.