In this study, an attempt was made to synthesize phenylcarbamoyl chitosan (PC-Cts) via complexation of chitosan with surfactant sodium dodecyl sulfate (SDS). SDS-chitosan complex was prepared simply by mixing acid solutions of chitosan and SDS. The complex was then reacted with phenyl isocyanate in dimethyl sulfoxide to yield PC-Cts. The molecular structures of the products were characterized by ¹H NMR spectroscopy. In ¹H NMR spectra of product samples, resonance signals characteristic of phenylcarbamoyl groups appeared together with those of chitosan. From this result, it was reasonably suggested that phenylcarbamoylation of chitosan was achieved by the procedure employed in this study. The ¹H NMR data were also used to determine the substitution parameters, including degree of substitution (DS), molar substitution (MS), degree of polymerization in the side chains (DP_S), and residual SDS content. The parameters varied with changes in reaction conditions. From these molecular characterization, the reaction pathway was proposed.

抄録全体を表示

モノカルボキシメチル化キトサン,N,N-ジカルボキシメチル化キトサン(IDA型キトサン)並びにジエチレントリアミン五酢酸型キトサン(DTPA型キトサン)を合成し,金属イオンの吸着特性を調べた.1mol/dm³の硝酸アンモニウム水溶液からの銅(II)イオンの吸着の起こるpHの順序はDTPA型キトサン≪IDA型キトサン<モノカルボキシメチル化キトサン<キトサンの順であった.銅の飽和吸着量はモノカルボキシメチル化キトサン以外はいずれも市販のキレート樹脂のそれよりも大きかった.DTPA型キトサンの二価の卑金属に対する吸着は低いpHから起こり,ニッケル/コバルトの分離係数は10程度に達した.更にDTPA型キトサンは軽希土の分離に対しても優れており,セリウム/ランタン及びネオジム/プラセオジムの分離係数はそれぞれ5.76及び2.27に達した.

抄録全体を表示

For the complex films composed of various molar (repeat unit) ratios of chitosan and carboxymethyl chitin (CM chitin) moisture sorptions were measured at 20°C, 65%RH and 20°C, 90%RH and water sorptions were measured in 5, 000-fold as much water as complex film after 24h at 30°C. Hygroscopicities of complex films became higher as the increase of the content of CM chitin irrespective of relative humidity and they did higher independent of the composition of complex film at 90%RH compared with those at 65%RH. Water sorptions of complex films were lower as molar (repeat unit) ratios of chitosan and CM chitin were in the range of 0.4/0.6 to 0.3/0.7. Except this range water sorptions of complex films were higher. The lowest value in water sorption was seen in approximately 1.0 of -NH₂/-COOH ratio, because it is then easy for chitosan and CM chitin to form polyion complex.

抄録全体を表示

An electrode covered with chitin-chitosan composite film was constructed to monitor binding between protein and ligand. Chitin, which is one of the extracellular matrixes, was dissolved in an organic solvent of N,N-dimethylacetoamide and 1-methyl-2-pyrrolidone. Because chitosan powder remained undissolved, it was considered to be a reaction field of biomolecule interactions. To examine whether the film was powerful, avidin and biotin were selected as a model of a protein and its ligand. Biotin moieties were introduced to active amino groups of the chitosan with a biotinylation reagent. To evaluate the binding on the film, biotin labeled with an electroactive daunomycin was used as a probe. As a result, an oxidation peak of the labeled biotin decreased. This was because the labeled biotin was held in the binding sites of avidin for biotin not used to be immobilized on a biotin-modified chitosan particle. Consequently, the binding could be monitored on the chitin-chitosan film with high biocompatibility. The procedure becomes a new method to evaluate binding between protein and ligand.

抄録全体を表示

Due to a remarkable deterioration of material properties when chitosan film is dry-heat-sterilized,chitosan film is conventionally sterilized with the gas sterilization method.
However, there is a potential risk of adverse effects of gas residue on a living body system. In this study, the film was sterilized under ⁶⁰Co γ-ray irradiation, and changes in properties were investigated.
The main conclusions were as follows:
1.The tensile strength of chitosan film D70(Deacetyl 70%)with a lower level of deacetyl degree markedly decreased. On the other hand, films D85 (Deacetyl 85%), and D99(Deacetyl 99%)did not show any reduction in tensile strengths.
2. The tensile elongation of all films after the ⁶⁰Co γ-ray irradiation decreased. Among them,the film(Deacetyl 70%)showed the largest reduction in tensile elongation.
3. It was also observed that the ⁶⁰Co γ-ray irradiation caused film discoloration of turning yellowish.
4. The molucules of all chitosans after the ⁶⁰Co γ-ray irradiation decreased.

抄録全体を表示

Chitin is an absorbable agent used to promote wound healing and hemostasis, and is also used in medical treatment. We investigated the effects of carboxymethyl-chitin (CM-chitin), a water-soluble derivative of chitin, on bone augmentation.
Four maxillary incisors were extracted from 5 adult Crab-eating Macaques, then the extraction sockets on the subjects' right sides were immediately filled with CM-chitin (experimental sites), while the left sides were left unfilled (control). One, two, four, eight, and twelve weeks after the procedure, the animals were euthanized and acrylic resin was injected via the common carotid arteries. Bone-microvascular corrosion casts were made and observed using scanning electron microscopy to determine the volume ratio of newly-formed bone in each socket.
After 1 week, newly-formed capillary networks were observed in the sockets of the experimental sites. After 2 weeks, the sockets in both the experimental and control sites were filled with newly-formed capillary networks. After 4 weeks, newly-formed bone was observed in the sockets of both sites and the sockets were also filled with newly-formed bone after 8 weeks. After 12 weeks, trabecular bone was thicker and more compressed than after 8 weeks. Image analysis showed that the volume ratio of newly-formed bone was not significantly different between the experimental and control sites.
We concluded that CM-chitin does not obstruct bone augmentation in extracted tooth sockets and is useful to promote angiogenesis in the early stages.

抄録全体を表示

This study was performed to investigate release of Ca ion from non-crystal calcium phosphate using the specimen which underwent heating at 800℃,1000℃, and 1100℃. The quantity of Ca ion and pH value was measured 1 day, 1 week, 2 weeks, 4 weeks and 8 weeks after immersion. The main results were as follows:
1. Non-crystal calcium phosphate showed the maximum amount of release for calcium ion.
2. Sintering of Hydroxyapatite at 1100℃ showed maximum amount of release for calcium ion.
3. By increasing the immersion, amount of Ca ion was decreased.
4. Relationship between amount of Ca ion and pH value was not clear.
5. Non-crystal calcium phosphate heated at 1000℃ and 1100℃ was identified as well-crystallized Hydroxyapatite.
6. Non-crystal calcium phosphate heated at 1000℃ and 1100℃ was observed as crystals on the surface of powder.

抄録全体を表示

Chitin (CHN) and three kinds of chitosan with deacetylation degrees of 50, 67 and 96%, named CHA 50, CHA 67 and CHA 96, respectively, were used for the preparation of films of CHN, chitosan and chitin-chitosan mixtures. Namely, the CHN or chitin-chitosan mixtures (1:1, w/w) were each dissolved in a trichloroacetic acid-1,2-dichloroethane (7:13, w/w) mixture, and chitosan was dissolved in an aqueous acetic acid solution. After the dopes obtained were cast, films were formed by precipitation. The films of CHA 50 and CHA 67 absorbed water very well, but the other films showed only moderate water absorption. The films, except CHA 50, showed fair film strength against tension under wet conditions. The films, a commercial non-woven cloth known as Beschitin^®-W and gauze alone (control) were applied to dermal burn wounds on rats. The exudate accumulated in the treatment with the CHN film. The films of CHA 50 and CHA 67 disintegrated at 5-7 days after application. The reduction in wound surface area was investigated by determining the ratio of the treated areas to their initial sizes. The films of CHN and each chitosan did not reduce the wound surface area significantly as compared to the control. Beschitin^®-W was not effective in the latter stage. The films of CHA 96 and each chitin-chitosan mixture stuck to the wound surface well, absorbed the exudate well and eliminated the pus. The chitin-chitosan mixture films reduced the wound surface area most extensively.

抄録全体を表示

In oral and maxillofacial surgery, we often require wound dressing materials to cover bone or soft tissue defects and promote healing. We previously showed that materials made of chitin are suitable for this purpose.
Chitin changes its physical and biological properties according to its deacetylation level. However, no report has described the influence of the deacetylation of chitin on biocompatibility. To evaluate this issue, we performed in-vitro experimental studies using materials containing various levels of deacetylated chitin.
Human gingival fibloblast-like cells (HGF) and mouse osteoblast cells (MC 3 T3-E 1) were cultured on sheets made of non-deacetylated chitin and, 35%, 50%, and 70% deacetylated chitin (DAC-0, DAC-35, DAC-50 and DAC-70, respectively). The growth of HGF and MC 3 T 3-E 1, and alkaline phosphatase (ALPase) activity of MC 3 T 3-E 1 were measured. The growth of these cells on the materials was also studied by SEM.
The biocompatibility of DAC-35 with these cells was high. Levels lower or higher than 35% deacetylated chitin were less biocompatible. Especially, DAC-50 and DAC-70 suppressed the growth and differentiation of these cells.

抄録全体を表示

Chitin was used for postoperative treatment of 36 patients undergoing nasal and paranasal sinus surgery. Chitin, a mucopolysaccharide purified from the crab's crust, has an action to promote wound healing. This chitin was used in sheet or stick form or applied to the gauze.
Chitin in sheet or stick form was not more useful than the conventional gelatinized sponge, which had to be changed every 24 hours due to its frangility and nonfusibility. We found that the gauze coated with chitin on both sides as thin as 2 mm was the most useful. These chitin gauzes were used in 21 patients after conchotomy and/ or deviatomy.
Advantages of this tampon are as follows: 1. Its bulkiness decreased the number of tampons, three on an average, for one nasal cavity. This could save time.2. Extraction was easy and painless compared to the ordinary gauze. Disadvantages are lower pressing ability due to its elasticity and possible infections medium of chitin.

抄録全体を表示

Pure chitosan was prepared from cuticle of crab shells by hydrothermal methods. The hydrothermal treatment was useful for demineralization, deproteination and deacetylation of cuticle. The hydrothermal treatment of cuticle with 2 M HC1 solution at 120 °C for 1 h brought about demineralization up to 100% (Fig.2), then the demineralized product was deproteinated and deacetylated significantly by the hydrothermal treatment with 15 M NaOH solution at 150 °C for 1 h. These processes of deproteination and deacetylation could be carried out at the same time. Furthermore, these hydrothermal treatments brought about a considerable reduction in time (Fig.4). Highly deacetylated chitosan from cuticle thus treated hydrothermally had molecular weight of about 7.4 x 10⁴.

抄録全体を表示

の土壌への施用がイネ個体群の物質生産に及ぼす影響を明らかにするため, 乾物生産特性および子実生産特性について検討した.1994年および1996年は施用量(50gm^-2, 100gm^-2, 200gm^-2および500gm^-2)が増加するにつれて玄米重が増加する傾向が認められ, 500g区は化成肥料区とほぼ同等の玄米重が得られた.1995年はコブノメイガが大発生し葉色が濃い500g区と化成肥料区においては葉が食害を受けたため, 玄米重はすべての施用区と化成肥料区では差異が認められなかった.1996年の収量構成要素の調査結果から1m²当たりの籾数が増加するにつれて玄米量が増加する傾向が認められた.登熟歩合は無施用区とすべての施用区では約90%であったが, 化成肥料区は低かった.これは, 化成肥料区では全生育期間を通じてLAIが高く, 出穂後は多粒による穂の遮光も加わることにより受光態勢が悪化しCGRが低下したことが原因と考えられた.これに対して, 500g区ではLAIが最大約4.5で出穂後も受光態勢が良好でCGRが高く維持された結果, 化成肥料区の玄米重に匹敵する収量を得ることができたと考えられた.

抄録全体を表示

廃食用油脂を食品として利用可能な品質に再生できれば, その排出量が減少して資源と環境の保護に役立つ。そこで, 廃食用油脂再生を目的として開発された活性炭・アルカリ包括キトサンゲルビーズを用いて, 発生源の異なる多数の廃食用油脂を対象として再生処理実験を行った。その結果, 極めて簡単な操作により油脂の劣化の指標であるAV (酸価) を低減可能であり, 脱色脱臭作用が認められた。また・水分・POV (過酸化物価) , IV (ヨウ素価) などの変化が少なく, 家庭用などの小規模廃食用油脂再生処理方法として適していることがわかった。キトサンゲルビーズの調製条件や反応条件などを検討した結果, 処理能力を高めるためにはキトサンゲルビーズを破砕して, 含水率を50～65%程度にするのが良く, 加温や攪拌により処理能力を高めることができた。また, キトサンの代わりに寒天を用いた活性炭・アルカリ包括寒天ゲルビーズ法でも同様な処理能力が得られた。

抄録全体を表示