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Volume 17 (1992)
- Issue 6 Pages 352-
- Issue 5 Pages 274-
- Issue 4 Pages 216-
- Issue 3 Pages 128-
- Issue 2 Pages 58-
- Issue 1 Pages 2-
Volume 17, Issue 4
Displaying 1-6 of 6 articles from this issue
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Masaharu Asano, Masaru Yoshida, Hideki Omichi, Hidetoshi Yamanaka1992 Volume 17 Issue 4 Pages 216-227
Published: July 01, 1992
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSStudy of biodegradable polymers for application in drug delivery systems is reviewed. Such biodegradable polymers as poly (a-amino acid), poly (α-hydroxy acids), and copolymers consisting of α-amino acids and α-hydroxy acids were synthesized by means of N-carboxy α-amino acid anhydride (NCA), direct polycondensation without the use of catalysts, and O-nitrophenylsulfenyl-N-carboxy α-amino acid anhydride (Nps-NCA), respectively.
The biodegradation profiles of these polymers can be roughly classified into three patterns, parabolic-type, linear-type, and S-type, according to kind of polymer, molecular weight, crystallinity, and morphology. The drugs incorporated into matrices by a melt-pressing technique newly developed are applied to animal experiments and clinical cases.View full abstractDownload PDF (1518K) -
Masao Gotoh, Isao Karube1992 Volume 17 Issue 4 Pages 228-237
Published: July 01, 1992
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSThe present review describes the FET-biosensor using polyvinylbutyral (PVB) membrane. The PVB membrane was applied to the surface of the silicon nitride which is the gate insulator of the IS-FET (Ion Sensitive Field Effect Transistor). The membrane exhibited good adhesive properties and was used for biomolecules immobilization, such as urease. H+-ATPase, etc.. The water content of the membrane was 27.6% with a thickness of 23, am. The surface structure of the membrane was observed by scanning electron microscopy, which revealed a regular porous microfilter arrangement with a mean pore diameter of 0.25 μm. Immobilized urease activity in this membrane was approximately 20% higher than when a urease-triacetylcellulose membrane was used. Using this polyvinylbutyral membrane, urea sensor, ATP sensor, acetylcholine sensor and HSA sensor were constructed. The new type device of ISFET was also constructed from amorphous silicon. From this device and PVB membrane, glucose sensor, hypoxanthine sensor and inosine sensor were constructed.View full abstractDownload PDF (1322K) -
Hiroki Katono, Naoya Ogata1992 Volume 17 Issue 4 Pages 238-245
Published: July 01, 1992
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSMolecular design of thermo-sensitive hydrogels was discussed. Interpenetrating polymer networks (IPNs) composed of poly (acrylamide (AAm)-co-butyl methacrylate (BMA)) have been investigated in terms of temperature dependence of swelling and their application to thermo-responsive drug delivery. PAAm and PAAc formed polymer complex at lower temperature by hydrogen bonding, and the complex dissociated at above a certain temperature at which the complex initiated dissociation all at once due to zipper effect. The IPNs showed lower swelling at lower temperatures and higher swelling at higher temperatures due to complex formation/dissociation change, exhibiting drastic change at around 25°C due to the zipper effect. However, the temperature, 25°C, is too low to apply to practical use. To shift the temperature to body temperature, poly (N-acrylylglycinamide) (PAG) was used instead of PAAm. AG has two amide groups in the side chain, which was considered to strengthen stability of polymer complex by hydrogen bond with PAAc. The IPN composed of PAG and PAAc actually demonstrated swelling/shrinking change at around 40°C. N, N-dimethylacrylamide (DMAAm) was also used for the same purpose with AG. DMAAm is a strong acceptor for hydrogen bonding. Incorporation of DMAAm into PAAm strengthened stability of PAAm/PAAc complex, and shifted the changing temperature of formation/dissociation to higher. In conclusion, the switching temperature of ON-OFF drug release could be controlled by proper molecular design of complexation sites of hydrogen bonding polymer complex.View full abstractDownload PDF (1070K) -
Trong Q. Nguyen, Ruxandra Gref, Aziz Essamri, Jaafar Elyassini, Jean N ...1992 Volume 17 Issue 4 Pages 247-256
Published: July 01, 1992
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSWhen hydrophilic dense films made from a series of Polyvinylalcohol (PVA) samples differing by their residual acetyl content are used to dehydrate by pervaporation water-organic solvent mixtures, it turns out that the selectivity decreases while the permeability greatly increases as the acetyl content increases. This behavior was attributed to the decrease in the ability of the polymer to form crystalline regions due to the disorganizing effect of the acetyl groups on the physical structure. Grafting of very small amounts of carboxylic groups of different natures and spatial distributions yields membranes whose swelling and pervaporation properties are explainable mainly by the difference in physical structures. This interpretation was confirmed by the results obtained with membranes of strictly identical chemical structure (100% hydrolyzed PVA) but with controlled crystallinity. Similar behaviors were observed with different water-solvent mixtures.
Differences in pervaporation properties were also observed in cellulose acetate membranes when they are annealed in hot water, although no significant crystallinity was observed in the annealed membranes. It can be concluded that the membrane physical structure (i. e. the chain organization in the membranes) has a strong influence on its pervaporation characteristics, and its control makes it possible the preparation of membrane of good performances.View full abstractDownload PDF (1153K) -
Kiyoshi Mishima, Yukio Suezaki, Masao Hashimoto1992 Volume 17 Issue 4 Pages 257-262
Published: July 01, 1992
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSLamellar structure of phospholipid vesicles, obtained by short time ultrasonic radiation, was studied by using negative stain electron microscopy. It is expected that the number of lamellae are randomly distributed over a possible region which is determined by size of the fragments torn by the radiation. However, a more restricted distribution in the number of lamellae was observed, e. g., there were no larger unilamellar vesicles and no vesicles with a larger number of lamellae. The result could be explained in terms of the interbilayer interaction and the bending elastic energy considering the high curvature effect of bilayers. This suggested that sonicated vesicles were formed inorder to take a mechanically stable lamellar structure.View full abstractDownload PDF (787K) -
Tzong-Jeng Chu, Mu-Hoe Yang1992 Volume 17 Issue 4 Pages 263-269
Published: July 01, 1992
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSThe relation, Vw, o=Vw, l (1+bΔP), was proposed to obtain a modified solution -diffusion model equation which can be studied the transport phenomena of the water permeation in a swollen PVA membrane on the effects of heat treatment. The PVA membrane was heat treated at 180°C by a different time respectively, and then, the experiments were carried out in the range of 20°to 50°C and the pressure region of 10 to 80 atm, to obtain the water diffusion apparent activation energy, diffusion coefficient, and compressive coefficient, the relationship between flux for water permeation and applied pressure or temperature, the modified solution diffusion equation and Arrhenius equation have been used.
The diffusion apparent activation energy was obtained in the range of 4.60 to 6.70 kcal/mole, and depended on the heat treatment time of PVA membrane. On the other hand, it was found that relationship between flux of water and (Vw, o-Vw, l) exists to be a straight line and also an approximately linear relationship exists between the reciprocal of water flux and the reciprocal of applied pressure. The compressive coefficient, b value, decreased with increasing the heating time of PVA membrane.View full abstractDownload PDF (772K)
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