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1.
Langmuir ; 28(41): 14518-21, 2012 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-23031253

RESUMO

A liquid-crystalline (LC) polymer melt coating a glass support shows a remarkable wetting ridge pattern resulting from a "stick-and-break" phenomenon when submerged into water at a velocity of 20 cm/s. A series of parallel, regularly spaced wetting ridges of 0.2 µm height are formed perpendicular to the advancing direction of the plate at 1 µm intervals, and the pattern continues over a wide area (1 × 2 cm(2)). The ridges function as a narrow line diffraction grating, similar to a prism that separates white light into the spectrum of colors. This process provides new insight into the controlled nanofabrication of polymers that is low-cost and high-throughput.


Assuntos
Polímeros/química , Tamanho da Partícula , Propriedades de Superfície , Molhabilidade
2.
Biomacromolecules ; 13(4): 1002-9, 2012 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-22385343

RESUMO

Nowadays, biomaterials with amphiphilic properties are undergoing remarkable development. Here, we present one such development, in which we prepared amphiphilic graft copolymers, with a main chain composed of hydroxyethyl acrylamide (HEAA), to introduce hydrophilicity, and a side chain composed of poly(trimethylene carbonate) (PTMC) to introduce tunable hydrophobicity. These macromonomers were created with a novel molecular design, which introduced a ring-opening polymerization by the hydroxyl end group of HEAA in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, and were analyzed by (1)H NMR and gel permeation chromatography. The amphiphilic graft copolymers were shown to form a hydrogel, the swelling ratio of which was greatly influenced by the number of trimethylene carbonate units. These copolymers also exhibited the Tyndall phenomenon in aqueous solution; they aggregated spontaneously due to hydrogen bonding and hydrophobic interactions, and a sodium 8-anilino-1-naphthalenesulfonate (ANS) fluorescence probe was introduced into the hydrophobic domain. The solution property of ANS in the polymer solution was analyzed by fluorescence measurement and (1)H NMR. The maximum fluorescence wavelength of ANS shifted to shorter wavelengths as the degree of polymerization of the hydrophobic PTMC, the composition of the macromonomer, and the concentration of the copolymer increased. The resulting copolymer formed a polymer micelle structure due to the tunable hydrophobic domain formation in selected solvents. Therefore, these amphiphilic graft copolymers containing a PTMC segment are excellent candidates for use as hydrophobic drug delivery carriers.


Assuntos
Acrilamidas/síntese química , Géis/síntese química , Substâncias Macromoleculares/síntese química , Acrilamidas/química , Dioxanos/síntese química , Dioxanos/química , Géis/química , Interações Hidrofóbicas e Hidrofílicas , Substâncias Macromoleculares/química , Estrutura Molecular , Polímeros/síntese química , Polímeros/química
3.
PLoS One ; 17(10): e0275093, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36215235

RESUMO

The quality of the dietary habits of older adults is important for increasing healthy life expectancy. As with other physical senses, the senses of taste and olfaction change with age. In contrast to physical sensations that can be visibly compared with those of other people, taste and olfaction are personal sensations, making it challenging to infer associated changes. This study investigated the characteristics of taste and olfaction in healthy older adults and compared them with those of young adults. In the taste assessment, threshold values were measured using the whole-mouth method with a diagnostic assay kit (Tastedisc). The olfactory assessment measured the overall identification ability using a card-type olfactory identification test kit (Open Essence). Additionally, participants' subjective health awareness was measured using a visual analog scale. The taste and olfactory assessments results showed that the older group had lower overall sensory sensitivity than the young group, and that there was no correlation between taste and olfactory sensitivity in the older group, while a trend was observed in the young group. Moreover, there was no significant difference between the two groups regarding subjective health awareness, indicating that participants in our research considered themselves healthy regardless of age. This suggests that the subjective health awareness of older people in the health promotion class is somehow independent from their sensory ability.


Assuntos
Transtornos do Olfato , Paladar , Idoso , Autoavaliação Diagnóstica , Promoção da Saúde , Humanos , Transtornos do Olfato/diagnóstico , Olfato , Adulto Jovem
4.
J Phys Chem B ; 126(40): 8119-8127, 2022 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-36194857

RESUMO

Three kinds of bent-shaped dimeric molecules are synthesized by fluorine substitution of C16 molecules, and influences of the substitution on the polar smectic phases are examined. The fluorine-substituted C16 molecules form the SmAPF and SmCAPA phases. The transition temperatures decrease by 20-30 °C without significantly changing the temperature span of the smectic phase, and the switching rates to the ferroelectric state become 5-10 µs, which are fairly shorter than 250 µs of C16. These behaviors are considered to be caused by the decrease in the intermolecular force and the decrease in the viscosity. The anchoring behavior also appears to be different. On the indium tin oxide (ITO)-coated cell, the fluorine-substituted molecules are homogeneously aligned with the bent (polar) axes perpendicular to the surface, while the bent axes of ordinary bent-shaped molecules lie parallel to the surface. This may be attributable to the repulsion between the fluorine and ITO electrodes. Further, the fluorine substitution can increase the dipole moment of the molecule. The largest dipole moment obtained is 7.94 D, and this leads to a huge reversal polarization of 2.42 µC cm-2, which is much higher compared to those reported in the bent-shaped molecules.


Assuntos
Cristais Líquidos , Eletrodos , Flúor , Polímeros , Temperatura
5.
Anal Chem ; 81(16): 6923-8, 2009 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-19606875

RESUMO

In this study, we fabricated polyelectrolyte multilayers (PEMs) on a polystyrene (PS) plate by a simple and novel alternate drop coating process (Acta Biomaterialia 2008, 4, 1255-1262), leading to the construction of a functional platform for improving conventional enzyme-linked immunosorbent assay (ELISA) systems. Poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) were used as cationic and anionic polyelectrolytes, and then positively or negatively charged surfaces were obtained on the PEMs. The PDDA/PSS PEMs on the PS plate had the following favorable characteristics. On the positive PEMs, the coverage of the blocking reagent (ovalbumin from egg white: OVA) was over 100% by electrostatic interaction between the protein and PEMs, hence, nonspecific adsorption from the secondary antibody was efficiently suppressed. Moreover, the positive PEMs showed higher sensitivity on the ELISA than the negative PEMs, including the PS plate. Regularly oscillating behavior for sensitivity (specific signal-to-noise ratio) was observed on 1-10-step assemblies. The calibration curves for antigen detection on the positive PEMs had wide range of concentration from 0.002 to 5 microg/mL, and largest change in signal as compared with the negative PEMs and the PS plate. In summary, we discovered that positive PEMs possessed excellent performance for ELISA systems, and PEMs could easily improve the immunoassay with a convenient process and diverse substrates.


Assuntos
Eletrólitos/química , Imunoensaio/métodos , Poliestirenos/química , Adsorção , Anticorpos/imunologia , Ensaio de Imunoadsorção Enzimática , Limite de Detecção , Ovalbumina/imunologia
6.
J Phys Chem B ; 113(16): 5341-4, 2009 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-19326900

RESUMO

We present an interesting phenomenon of the mechanically aligned monodomain state of polar nematic liquid crystals transforming into the polydomain one. This unusual transformation may result from mismatching of the dipolar vectors. By stretching or shear-flowing the polar nematic liquid crystal, the perfect orientation can be achieved with respect to the long molecular axis, but the misorientation exists with respect to the polar vector. After the prolonged annealing, then, the free energy of the molecules is minimized by producing new defects which satisfy the continuity of polar orientation, but lead to the loss of macroscopic molecular orientation.


Assuntos
Hidrocarbonetos Aromáticos/química , Cristais Líquidos/química , Poliésteres/química , Físico-Química , Estrutura Molecular , Raios X
7.
Biomacromolecules ; 9(2): 426-30, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18179172

RESUMO

Poly(N-vinylacetamide) hydrogels (PNVA gels) were synthesized to investigate their basic characteristics for biomedical applications such as water contact angles, protein uptake, and mouse fibroblasts (L-929) cell adhesion. Because PNVA gels show hydrophilic features, double network (DN) hydrogels were prepared by the secondary polymerization of N-vinylacetamide (NVA) or acrylamide (AAm) in PNVA gels (NVA/NVA DN gels and NVA/AAm DN gels, respectively), in order to vary PNVA gel features for biocompatibility. Contact angles for both DN gels decreased to around 20 degrees, whereas both PNVA and PAAm gels were over 30 degrees. On the other hand, more protein tended to adsorb to DN gels than single network hydrogels. Compared to PNVA gel, cell adhesion and proliferation on NVA/NVA DN gel were improved with less swelling ratio and much protein uptake, while no significant difference was observed on NVA/AAm DN gel, probably due to more hydrophilic character, supported by lowest water contact angle. These complicated structure change in DN gels would provide a new methodology for tuning the biocompatibility of hydrogels and for controlling surface hydrophilic characteristics and network structures.


Assuntos
Acetamidas/química , Proliferação de Células , Hidrogéis/química , Polivinil/química , Polivinil/farmacologia , Acetamidas/farmacologia , Animais , Adesão Celular/efeitos dos fármacos , Adesão Celular/fisiologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/fisiologia , Hidrogéis/farmacologia , Camundongos
8.
J Comb Chem ; 10(1): 135-41, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18052330

RESUMO

Six-types of palladium-catalyzed coupling, Mizoroki-Heck, Migita-Stille, Sonogashira, carbonylative esterification, carbonylative Stille, and carbonylative Sonogashira reactions, were performed on a polymer support. The above coupling reactions of m- and p-substituted aromatic rings, followed by carbonylative esterification with m- and p-substituted anisol derivatives were carried out in a combinatorial manner. Acid cleavage from the polymer-support provided the conjugated aromatic ring systems 1 and 2, which are the core parts of rodlike liquid crystals.


Assuntos
Técnicas de Química Combinatória/métodos , Cristais Líquidos/química , Paládio/química , Polímeros/química , Bibliotecas de Moléculas Pequenas/síntese química , Derivados de Benzeno/química , Catálise , Estrutura Molecular , Bibliotecas de Moléculas Pequenas/química
9.
Acta Biomater ; 4(5): 1255-62, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18436492

RESUMO

Polyelectrolyte multilayers were formed on a quartz crystal microbalance (QCM) substrate by using polyelectrolyte droplets. In this study, poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrene sulfonate) (PSS) were used. The formation of the multilayers was evaluated in terms of changes in the frequency of the QCM. The polymer droplet could be used to fabricate a polyelectrolyte multilayer. Model protein adsorption such as that in bovine serum albumin and its release behavior were compared with the ionic strength in the media. Moreover, the secondary structure of the adsorbed protein was evaluated by analyzing its circular dichroism spectrum. The adsorbed protein maintained its secondary structure on the layer-by-layer (LbL) membrane. This result strongly supports the fact that the multilayers fabricated by the polyelectrolyte droplet were similar in quality to those fabricated via an alternating adsorption process. In summary, the polyelectrolyte droplet method is a good candidate for the preparation of LbL assemblies in the biomedical field.


Assuntos
Materiais Revestidos Biocompatíveis/química , Eletrólitos/química , Microfluídica/métodos , Polietilenos/química , Polímeros/química , Proteínas/química , Compostos de Amônio Quaternário/química , Ácidos Sulfônicos/química , Adsorção , Teste de Materiais , Ligação Proteica , Propriedades de Superfície
10.
J Biomed Mater Res A ; 83(3): 845-52, 2007 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-17559128

RESUMO

We investigated the fundamental properties of quick-forming hydroxyapatite (HAp)/agarose gel composites, and evaluated their potential as an injectable bone substitute. From scanning electron microscope observations, the HAp/agarose gel composites produced by an innovative electrophoretic process showed an interconnecting structure with the HAp particles. The diameter of the HAp particles was roughly 1 microm, and the total amount of HAp particles was estimated by a quantification of the calcium ions. In the case of 1 mg of dry composite, 10 microg of HAp was formed in the agarose gel. Moreover, X-ray diffraction analysis revealed that the HAp particles had an amorphous structure, so the HAp particles were expected to dissolve under physiological conditions relative to the HAp with higher crystallinity. The advantages of the resultant HAp/agarose gel composites are ease of handling, close contact with the surrounding tissues, and ease of use as an injectable material. As a preliminary animal study, the composites were implanted into the medial femoral condyle of rabbits. After implantation, the process of bone regeneration was evaluated by microfocus-computed tomography (microCT) and histological analysis. At 2 weeks postoperatively, newly-formed bone was observed at the edge of the bone defect site, and at 4 weeks postoperatively, excellent bone regeneration was observed. The implanted composite gradually degraded, and disappeared at 8 weeks postoperatively. This result indicated that the composite dissolved rapidly, and was replaced by newly-formed bone. Quick-forming HAp/agarose gel composites may be a good candidate as an injectable biomaterial, particularly in the fields of orthopedic, oral, and maxillofacial surgery.


Assuntos
Implantes Absorvíveis , Regeneração Óssea , Substitutos Ósseos , Durapatita , Sefarose , Animais , Durapatita/química , Fêmur/citologia , Géis , Teste de Materiais , Coelhos , Sefarose/química
11.
Biomaterials ; 27(9): 1955-62, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16239028

RESUMO

For practical application of a liver assist system with a tissue-conjugated hollow fiber membrane (HFM) bioreactor used in an extracorporeal therapy, it would require a highly sophisticated HFM which has both hemocompatibility on one side and cytocompatibility on the other side. In this study, we present a cellulose acetate (CA) HFM modified with 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymers (PMB30 (MPC-co-n-butyl methacrylate) and PMA30 (MPC-co-methacrylic acid) for preparing a novel liver assist HFM bioreactor. A CA/PMB-PMA30 HFM modified asymmetrically on the inner and outer surface with the PMB30 and PMA30 was prepared successfully. Analysis with an X-ray photoelectron spectroscope showed that the intensity of the phosphorus atom attributed to the MPC units on the outer surface of the modified HFM was stronger than that of the inner surface. The PMA30 was immobilized on the outer surface of the CA/PMB30 blend HFM by a chemical condensation reaction. The CA/PMB-PMA30 HFM showed good water and solute permeability in comparison with the CA HFM. The morphologies of the adherent hepatocytes were round in shape in comparison with the cells that adhered on CA HFM. Furthermore, hepatocytes cultured on the inner surface of the CA/PMB-PMA30 HFM showed higher functional expression in terms of urea synthesis and albumin synthesis than that of the CA HFM.


Assuntos
Reatores Biológicos , Fígado Artificial , Membranas Artificiais , Metacrilatos/química , Fosforilcolina/análogos & derivados , Animais , Células Cultivadas , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Metacrilatos/síntese química , Metacrilatos/toxicidade , Permeabilidade , Fosfolipídeos/química , Fosforilcolina/síntese química , Fosforilcolina/química , Fosforilcolina/toxicidade , Polímeros/química , Ratos
12.
J Biomed Mater Res A ; 77(1): 19-27, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16345080

RESUMO

To obtain a bioartificial kidney composed of a porous polymer membrane and renal cells, a polysulfone (PSf) membrane (PSM) blended with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer was prepared. The PSM flat membrane with a porous structure could be prepared from the polymer blend containing 1 wt % of the MPC polymer in PSf by the phase inversion technique in a dry-wet process. Asymmetrical surface properties were observed on both sides of the membrane surfaces. That is, the sponge layer formed at the substrate-contacting surface of the membrane had 10-20 microm pores, but the pores in the micrometer range could not be observed for a skin layer formed at the air-contacting surface of the membrane. At the sponge layer surface, the MPC unit composition was 7 times larger than that at the skin layer surface. The amount of proteins adsorbed on the surface corresponded to the MPC unit composition. On the skin layer, a small amount of adsorbed proteins and platelet adhesion could be suppressed compared with those on the sponge layer. However, the skin layer had a moderate protein adsorption, so it showed a sufficient cytocompatibility to enable renal tubule epithelial cells to adhere and proliferate in the membrane. Thus, it functioned well as a renal tubule. Therefore, because of both its hemocompatibility and cytocompatibility, we could conclude that the PSM membrane is useful for as a renal tubule device for a bioartificial kidney.


Assuntos
Órgãos Bioartificiais , Materiais Biocompatíveis/metabolismo , Membranas Artificiais , Fosfolipídeos/metabolismo , Polímeros/metabolismo , Sulfonas/metabolismo , Adsorção , Animais , Materiais Biocompatíveis/química , Plaquetas/metabolismo , Células Cultivadas , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Humanos , Teste de Materiais , Polímeros/química , Sulfonas/química , Propriedades de Superfície , Microglobulina beta-2/metabolismo
13.
Colloids Surf B Biointerfaces ; 50(1): 55-60, 2006 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-16730167

RESUMO

We investigated the preparation of polymer nanoparticles covered with phosphorylcholine (PC) groups and the immobilization of proteins in order to observe dual mode bioreactions on the nanoparticles. For the surface modification on the nanoparticles, a water-soluble amphiphilic phospholipid polymer with PC groups as a hydrophilic moiety was synthesized. In this polymer, an active ester group, which can immobilize proteins, was introduced. Using the phospholipid polymer as a solubilizer, poly(L-lactic acid) nanoparticles were prepared from its methylene chloride solution in an aqueous medium by the solvent evaporation method. The diameter of the nanoparticles was ca. 200 nm and the surface was covered with the PC groups and active ester groups. Proteins could immobilize on the nanoparticles under mild conditions by the reaction between the active ester group and amino group in the proteins. Both an antibody and enzyme were immobilized on the nanoparticles and bioreactions such as the antigen/antibody reaction and enzymatic reaction were observed. When an antigen was added to the suspension of the nanoparticles, aggregation of the nanoparticles occurred and then they precipitated. Also, the enzymatic reaction proceeded well when the enzyme substrate was added to the suspension. Based on these results, we provided polymer nanoparticles functionalized with both the antibody and enzyme, and the dual mode bioreactions could occur. We concluded that the novel polymer nanoparticles could be used for nano-/micro-scaled diagnostic and medical treatment systems.


Assuntos
Reatores Biológicos , Ácido Láctico/química , Metacrilatos/química , Nanoestruturas/química , Fosforilcolina/química , Polietilenoglicóis/química , Polímeros/química , Anticorpos Monoclonais/química , Imunofluorescência , Metacrilatos/síntese química , Poliésteres , Polietilenoglicóis/síntese química , Propriedades de Superfície
14.
Mater Sci Eng C Mater Biol Appl ; 68: 65-69, 2016 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-27523997

RESUMO

A novel hydrogel having hydrophobic oligo segments and hydrophilic poly(acrylamidoglycolic acid) (PAGA) as pH responsive polymer segments was designed and synthesized to be used as a soft biomaterial. Poly(trimethylene carbonate) (PTMC) as the side chain, for which the degrees of polymerization were 9, 19, and 49, and the composition ratios were 1, 5, and 10mol%, was used as the oligo segment in the hydrogel. The swelling ratio of the hydrogel was investigated under various changes in conditions such as pH, temperature, and hydrogen bonding upon urea addition. Under pH2-11 conditions, the graft gel reversibly swelled and shrank due to the effect of PAGA main chain. The interior morphology and skin layer of the hydrogel was observed by a scanning electron microscope. The hydrogel composed of PAGA as the hydrophilic polymer backbone had a sponge-like structure, with a pore size of approximately 100µm. On the other hand, upon increasing the ratio of trimethylene carbonate (TMC) units in the hydrogel, the pores became smaller or disappeared. Moreover, thickness of the skin layer significantly increased with the swelling ratio depended on the incorporation ratios of the PTMC macromonomer. Molecular incorporation in the hydrogel was evaluated using a dye as a model drug molecule. These features would play an important role in drug loading. Increasing the ratio of TMC units favored the adsorption of the dye and activation of the incorporation behavior.


Assuntos
Resinas Acrílicas , Dioxanos , Portadores de Fármacos , Hidrogéis , Polímeros , Resinas Acrílicas/síntese química , Resinas Acrílicas/química , Resinas Acrílicas/farmacocinética , Dioxanos/síntese química , Dioxanos/química , Dioxanos/farmacocinética , Portadores de Fármacos/síntese química , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Hidrogéis/síntese química , Hidrogéis/química , Hidrogéis/farmacocinética , Interações Hidrofóbicas e Hidrofílicas , Polímeros/síntese química , Polímeros/química , Polímeros/farmacocinética
15.
PLoS One ; 11(12): e0165842, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27935970

RESUMO

An Asian spice, Szechuan pepper (sanshool), is well known for the tingling sensation it induces on the mouth and on the lips. Electrophysiological studies have revealed that its active ingredient can induce firing of mechanoreceptor fibres that typically respond to mechanical vibration. Moreover, a human behavioral study has reported that the perceived frequency of sanshool-induced tingling matches with the preferred frequency range of the tactile rapidly adapting (RA) channel, suggesting the contribution of sanshool-induced RA channel firing to its unique perceptual experience. However, since the RA channel may not be the only channel activated by sanshool, there could be a possibility that the sanshool tingling percept may be caused in whole or in part by other sensory channels. Here, by using a perceptual interference paradigm, we show that the sanshool-induced RA input indeed contributes to the human tactile processing. The absolute detection thresholds for vibrotactile input were measured with and without sanshool application on the fingertip. Sanshool significantly impaired detection of vibrations at 30 Hz (RA channel dominant frequency), but did not impair detection of higher frequency vibrations at 240 Hz (Pacinian-corpuscle (PC) channel dominant frequency) or lower frequency vibrations at 1 Hz (slowly adapting 1 (SA1) channel dominant frequency). These results show that the sanshool induces a peripheral RA channel activation that is relevant for tactile perception. This anomalous activation of RA channels may contribute to the unique tingling experience of sanshool.


Assuntos
Amidas/farmacologia , Mecanorreceptores/efeitos dos fármacos , Mecanotransdução Celular/fisiologia , Percepção do Tato/efeitos dos fármacos , Tato/fisiologia , Adulto , Amidas/química , Feminino , Dedos/fisiologia , Humanos , Masculino , Mecanorreceptores/metabolismo , Corpúsculos de Pacini/efeitos dos fármacos , Corpúsculos de Pacini/metabolismo , Especiarias/análise , Percepção do Tato/fisiologia , Vibração
16.
Biomaterials ; 26(24): 5032-41, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15769539

RESUMO

In this study, we prepared cellulose acetate (CA) hollow fiber membranes (HFMs) modified with poly (2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate)(PMB30 and PMB80) by the dry-jet wet spinning process. The physical and chemical structures of the HFMs were controlled in order to design highly functional HFMs that had suitable performance to each targeting HFM device used in a total hemopurification system. The CA HFMs modified with the MPC polymer, such as CA/PMB30, CA/PMB80, and CA/PMB30-80 HFMs, were successfully prepared by controlling the spinning conditions. The modified HFMs showed an improved performance in solute and water permeability, due to the modification by the hydrophilic MPC polymers. The CA/PMB30 and CA/PMB80 showed a high potential in an application for a high performance hemocompatible plasmapheresis and hemofilter device. Furthermore, CA/PMB30-80 HFM, modified asymmetrically with PMB30 and PMB80, showed a potential for application in an advanced total hemopurification system as a highly functional scaffold for a biohybrid renal tubule, or a liver assist bioreactor device, because of their enhanced permeability, hemocompatibility, and cytocompatibility.


Assuntos
Materiais Biocompatíveis/química , Celulose/análogos & derivados , Celulose/química , Hemofiltração/métodos , Rim/fisiologia , Membranas Artificiais , Fosfolipídeos/química , Diálise Renal/métodos , Animais , Adesão Celular/fisiologia , Linhagem Celular , Cães , Hemofiltração/instrumentação , Rim/citologia , Rins Artificiais , Teste de Materiais , Permeabilidade , Porosidade , Diálise Renal/instrumentação
17.
Biomaterials ; 26(34): 6853-62, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15978662

RESUMO

The mixed aqueous solutions of two water-soluble phospholipid polymers, such as poly[2-methacryloyloxyethyl phosphorylcholine(MPC)-co-methacrylic acid(MA)] (rPMA) and poly[MPC-co-n-butyl methacrylate(BMA)] (PMB), spontaneously form a hydrogel at room temperature without any chemical treatment due to hydrogen bonding formation between the carboxyl groups. With the objective of enhancing the hydrogen bonding efficiency, we have focused on the density of the carboxyl groups by controlling the chemical structure and monomer unit sequence. Thus, a random and an ABA-block-type MPC copolymer having carboxylic acids, poly[MPC-co-4-(2-methacryloyloxyethyl) trimellitic acid(MET)] (rPMT) and poly(MA)-poly(MPC)-poly(MA) (bPMA), have been designed. The purpose of this study is to investigate the gelation mechanism and physical properties of a hydrogel composed of rPMA and PMB (ABgel), one of bPMA and PMB (bABgel), and one of rPMT and poly(MPC-co-benzyl methacrylate) (PMBz) (TZgel). The Raman spectroscopic analysis and the rheological study of the dissolution behaviors indicated that the TZgel formation occurred due to inter- and intra-molecular hydrogen bonding formation between the carboxyl groups in the rPMT. The gelation mechanism of the bABgel was investigated by the dynamic light scattering measurement, the scanning electron microscopy observation and the rheological study. The results showed that the bPMA chains aggregate in the aqueous medium and transform into a hydrogel network structure. The bPMA needed much more gelation time than the rPMA due to this transformation. There was no difference between the gelation periods of the ABgel and the TZgel. The compression strengths of the ABgel and the bABgel showed no significant difference, while that of TZgel was lower than ABgel. The reason for this is that the polymer chains and bulky side chains of rPMT inhibit rearranging into a planar conformation and forming hydrogen bondings. These results lead to the conclusion that the properties of these MPC polymer hydrogels can be controlled by not only the chemical structure of the polymer but also the monomer unit sequence containing carboxyl groups.


Assuntos
Materiais Biocompatíveis/química , Cristalização/métodos , Hidrogéis/química , Fosfolipídeos/química , Polímeros/química , Água/química , Materiais Biocompatíveis/análise , Precipitação Química , Força Compressiva , Elasticidade , Hidrogéis/análise , Teste de Materiais , Conformação Molecular , Fosfolipídeos/análise , Polímeros/análise , Solubilidade , Soluções , Água/análise
18.
Biomaterials ; 25(1): 71-6, 2004 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-14580910

RESUMO

To maintain enzymatic activity during long-term storage by conjugation with water-soluble 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers (PMPC-COOH) having various molecular weights with a carboxylic group on the terminal, such compounds were synthesized as a polymer modifier using a photoinduced living radical polymerization technique. A poly(ethylene oxide) with a carboxyl group (PEO-COOH) was used as the control. The PMPC-COOHs were reacted with the amino groups of the enzyme, papain, via amide bonds. With an increase in the molecular weight in the range between 5 and 20K of the PMPC-COOH, the modification degree and alpha-helix content of the conjugated papain slightly decreased, but the remaining enzymatic activity did not depend on the molecular weight of the PMPC-COOH. However, when a much higher molecular weight PMPC-COOH (40K) was conjugated with a reduction in the modification degree, alpha-helix content was higher compared with the other PMPC-conjugated papain. Modification with PEO-COOH showed little reduction of the alpha-helix content of papain. The time dependence of the remaining enzymatic activity of the polymer-conjugated papains was evaluated during storage at 40 degrees C. The native papain diminished activity within one week. PEO-conjugated papain had decreased activity with time, but after one week it had half its initial level. The same tendency was observed when papain was modified with PMPC-COOHs 5 and 40K, that is, the enzymatic activity did not decrease even when they were stored for 4 weeks. We concluded that the PMPC chain could stabilize the enzyme by control of the molecular weight of the PMPC and modification degree to the enzyme.


Assuntos
Materiais Biocompatíveis/química , Metacrilatos/química , Papaína/química , Fosfolipídeos/química , Fosforilcolina/análogos & derivados , Fosforilcolina/química , Água/química , Materiais Biocompatíveis/síntese química , Ativação Enzimática , Estabilidade Enzimática , Enzimas Imobilizadas/química , Teste de Materiais , Polímeros/química , Ácidos Polimetacrílicos , Ligação Proteica , Solubilidade
19.
Biomaterials ; 24(28): 5183-90, 2003 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-14568435

RESUMO

The purpose of this study is to ascertain the applicable possibility of H(2)O(2) degradable hydrogel for fabrication of insulin release system synchronized with the change in the glucose concentration in the medium. The hydrogel was prepared by using 2-methacryloyloxyethyl phosphorylcholine (MPC) and crosslinker. The favorable characteristic of the hydrogel was H(2)O(2) concentration responsive degradation. The H(2)O(2) was utilized and produced by enzymatic reaction between glucose oxidase and glucose. Poly(MPC) (PMPC) was easily degraded in H(2)O(2) aqueous solution, and the PMPC hydrogel was also degraded in H(2)O(2) aqueous solution. The degradation mechanism was considered to be main chain scission of PMPC. The degradation profile was evaluated by using weight swelling ratio and volume swelling ratio. The weight swelling ratio of PMPC hydrogel firstly increased due to the reduction of crosslink density, then the ratio decreased to zero (complete degradation). The degradation profile was proportional to the H(2)O(2) concentration. Furthermore, volume swelling ratio also increased, and complex elastic modulus decreased with degradation in H(2)O(2) aqueous solution. These results indicated that the hydrogel was degraded by hydroxy and/or hydroperoxy radicals which was produced by H(2)O(2), the crosslink density and mechanical property decreased. The release profile from the hydrogel was estimated by using lipid microsphere (LM) as an insulin model. The LM was released with the degradation of PMPC hydrogel. Taking these results into account, the PMPC hydrogel was available for H(2)O(2) degradable hydrogel for synchronization with glucose concentration by using enzymatic reaction.


Assuntos
Implantes Absorvíveis , Hidrogéis/química , Peróxido de Hidrogênio/química , Sistemas de Infusão de Insulina , Insulina/química , Lipossomos/química , Teste de Materiais , Metacrilatos/química , Fosforilcolina/análogos & derivados , Fosforilcolina/química , Difusão , Estudos de Viabilidade , Insulina/administração & dosagem , Membranas Artificiais , Peso Molecular , Pressão Osmótica , Ácidos Polimetacrílicos
20.
Biomaterials ; 25(6): 1115-22, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-14615177

RESUMO

To develop new biomaterials for making medical devices, polymer alloys composed of a phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), and polyethylene (PE) were prepared. The PE/PMPC alloy membrane could be obtained by a combination of solution mixing and solvent evaporation methods using xylene and n-butanol mixture as a solvent. Moreover, thermal treatment was applied to improve the mechanical properties of the PE/PMPC alloy membrane. In the PE/PMPC alloy membrane, the PMPC domains were located not only inside the membrane but also at the surface. Surface analysis of the PE/PMPC alloy membrane with X-ray photoelectron spectroscopy, wettability evaluation, and dynamic contact angle measurements revealed that the phospholipid polar groups in the PMPC covered the surface even after thermal treatment. Blood compatibility tests with attention to platelet adhesion and change in morphology of adhered platelets showed that the PE/PMPC alloy membrane had excellent platelet adhesion resistance. We finally concluded that the PE/PMPC alloy could be used as biomaterials instead of poly(vinyl chloride)-based materials.


Assuntos
Materiais Biocompatíveis/química , Plaquetas/citologia , Plaquetas/fisiologia , Metacrilatos/química , Fosforilcolina/análogos & derivados , Fosforilcolina/química , Adesividade Plaquetária/fisiologia , Polietileno/química , Ligas/síntese química , Ligas/química , Materiais Biocompatíveis/síntese química , Células Cultivadas , Temperatura Alta , Humanos , Teste de Materiais , Membranas Artificiais , Conformação Molecular , Fosfolipídeos/síntese química , Fosfolipídeos/química , Polímeros/síntese química , Polímeros/química , Ácidos Polimetacrílicos , Cloreto de Polivinila/química , Propriedades de Superfície , Temperatura
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