Layer-by-layer assembly of multilayer films composed of streptavidin and biotinylated antibody by real-time biomolecular interaction analysis

Layer-by-layer assembly of multilayer films of streptavidin and biotinylated antibody was completed on the streptavidin coated surface. Real-time biomolecular interaction analysis (BIA) based on surface plasmon resonance technique was used to monitor the multilayer assembly in solution continuously. The results indicate that the uniform multilayer film can be fabricated successfully based on the strong interaction between streptavidin and biotin. The mean surface mass concentration of each adsorption layer is 1. 32 ng/mm(2) for biotinylated antibody, 2. 93 ng/mm(2) for streptavidin, according to the correlation of SPR response with surface concentration.

Assembly of alternating polycation and DNA multilayer films by electrostatic layer-by-layer adsorption

The assembly of alternating DNA and positively charged poly(dimethyldiallylammonium chloride) (PDDA) multilayer films by electrostatic layer-by-layer adsorption has been studied. The real-time surface plasmon resonance (BIAcore) technique was used to characterize and monitor the formation of multilayer films in solution in real time continuously. Electrochemical impedance spectroscopy (EIS) and UV-vis absorbance measurements were also used to study the film assembly, and linear film growth was observed. All the results indicate that the uniform multilayer can be obtained on the poly(ethylenimine)- (PEI-) coated substrate surface. The kinetics of the adsorption of DNA on PDDA surface was also studied by the real-time BIAcore technique; the observed rate constant was calculated using a Langmuir model (k(obs) = (1.28 +/- 0.08) x 10(-2) s(-1).

Formation of mesophase mono-domains and micro-structures in thin films of a series of copolyethers containing both odd-numbered methylene units

The structural and morphological evolution of mono-domains in thin films has been investigated for a series of liquid crystalline (LC) copolyethers. The copolyethers studied were synthesized by the reaction of 1-(4-hydroxy-4 ' -biphenylyl)-2-(4-hydroxyl-phenyl)propane (TPP) with 1,7-dibromoheptane and 1,11-undecane at different compositions (coTPPs-7/11). In contrast to the solution-cast thin films without annealing, which exhibit the isotropic homogeneous molecular orientation, mono-domains with a homeotropic alignment were found in coTPP-7/11(5/5) after the thin films were annealed in the high-temperature columnar phase (Phi '). Similar to the nucleation process in polymer crystallization, transmission electron microscopic observations show that small mono-domains appear in the initial stage of annealing, where molecules form a uniaxial in-plane chain orientation. With increasing annealing time, the molecular orientation gradually became tilted with respect to the substrate surface, and finally, a uniaxial homeotropic molecular orientation was achieved after a prolonged annealing time. The lateral size of mono-domains was found to increase continuously with annealing time and grew into a circular shape, indicating an isotropic lateral growth scheme which implies a hexagonal molecular packing proved by the electron diffraction experiments.

Electrostatic layer-by-layer assembly of polycation and DNA multilayer films by real-time surface plasmon resonance technique

The assembly of alternating DNA and positively charged poly(dimethyldiallylammonium chloride) (PDDA) multilayer films by electrostatic layer-by-layer adsorption has been studied. Real time surface plasmon resonance (BIAcore) technique was used to characterize and monitor the formation of multilayer films in solution in real time continuously. The results indicate that the uniform multilayer can be obtained on the poly(ethylenimine) (PEI) coated substrate surface. The kinetics of the adsorption of DNA on PDDA surface was also studied by real-time BIAcore technique, and the observed rate constant was calculated using a Langmuir model (k(obs) = (1.28 +/- 0.08) x 10(-2) s(-1)).

Lamellar single crystals of nylon-10,10 crown from a dimethylformamide solution

A new solvent, dimethylformamide (DMF), and the traditional solvent, 1,4-butanediol, were used to prepare single crystals of nylon-10,10 from a dilute solution. The lamellae grown from DMF inhabited a more perfect structure and regular shape than those crystals crystallized from traditional solvents such as 1,4-butanediol and glycerin. These thin and perfect lamellar crystals demonstrated patterns of variation in spacing different from those of melt-crystallized spherulites on heating. Specifically, the two main spacings slightly separated rather than continuously approaching each other when the temperature was greater than 180 degreesC. This is a novel phenomenon observed in nylons. Nevertheless, the usual pattern of change in spacing was observed during the cooling process. These lamellar crystals showed more compact spacing of the (002) and (010/100) planes than spherulites at room temperature. (C) 2001 John Wiley & Sons, Inc.

Enzymatic degradation of poly(epsilon-caprolactone)/poly(DL-lactide) blends in phosphate buffer solution

Blend films of poly(epsilon-caprolactone) (PCL) and poly(DL-lactide) (PDLLA) with 0.5 weight fraction of PCL were prepared by means of solution casting and their degradation behavior was studied in phosphate buffer solution containing Pseudomonas (PS) lipase. Enzymatic degradation of the blend films occurred continuously within the first 6 days and finally stopped when the film weight loss reached 50%, showing that only PCL in the blends degraded under the action of PS lipase in the buffer solution. These results indicate the selectivity of PS lipase on the promotion of degradation for PCL and PDLLA. The thermal properties and morphology of the blend films were investigated by differential scanning calorimetry, wide-angle X-ray diffraction and scanning electron microscopy (SEM). The morphology resulting from aggregate structures of PCL in the blends was destroyed in the enzymatic degradation process, as observed by SEM. These results confirm again the enzymatic degradation of PCL in the blends in the presence of PS lipase. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.

Detection of hydrazine, methylhydrazine and isoniazid by capillary electrophoresis with a 4-pyridyl hydroquinone self-assembled microdisk platinum electrode

Capillary electrophoresis (CE)/electrochemical detection (EC) for the simultaneous detection of hydrazine, methylhydrazine, and isoniazid has been developed with a 4-pyridyl hydroquinone self-assembled microdisk platinum electrode. Such an electrode has very high catalytic ability for hydrazines and they could be detected even at 0.0 V. The responses for hydrazine, methylhydrazine, and isoniazid are linear over 3 orders of detected concentration and of magnitude of 0.2-400 mu M, 0.2-400 mu M, 0.5 mu M-2 mM, with correlation coefficients of 0.9998, 0.9991, and 0.9982, respectively. And they could be detected to levels of 0.1, 0.1 and 0.2 mu M, respectively. This modified electrode was found to be very stable and reproducible when continuously used as detector for capillary electrophoresis for period of at least 4 weeks with no apparent loss of response. (C) 1999 Elsevier Science B.V. All rights reserved.

The suppression of Ge-132 on the Maillard reaction of BSA by fluorescence spectrum

The fluorescences of BSA and glycosylated BSA were observed respectively. The lambda(cm) of BSA was 340 nm; while the lambda(cm) of glycosylated BSA was 436 nm. Because the fluorescence spectra of them were different greatly, we can observe the suppression of Ge-132 on the Maillard reaction of BSA without any interference of itself. It was showed that the fluorescence intensity of glycosylated BSA increased continuously with the cultured time, Ge-132 may suppress the Maillard reaction of BSA greatly, and the suppressing efficicency would be 32 %. The key site of the Maillard reaction of BSA is free amino groups of alanine residues on N-terminal amino group, besides the epsilon-amino groups of intrachain Lysine residues.

Study of semicrystalline-amorphous diblock copolymers .1. Microphase separation, glass transition and crystallization of tetrahydrofuran methyl methacrylate diblock copolymers

The microphase separation, glass transition and crystallization of two series of tetrahydrofuran-methyl methacrylate diblock copolymers (PTHF-b-PMMA), one with a given PTHF block of M(n) = 5100 and the other with a given PTHF block of (M) over bar(n) = 7000, were studied in this present work. In the case of solution-cast materials, the microphase separation of the copolymer takes place first, with crystallization then gradually starting in the formed PTHF microphase. The T-g of the PMMA microphase shows a strong dependence on the molecular weight of the PMMA block, while the T-g of the PTHF microphase shows a strong dependence on the copolymer composition. The non-isothermal crystallization temperature (T-c) of the diblock copolymer decreases rapidly and continuously with the increase in the amorphous PMMA weight fraction; the lowest T-c of the copolymer is ca. 35 K lower than the T-c of the PTHF homopolymer. There also exists a T-c dependence on the molecular weight of the PTHF block. In addition, when the major component of the copolymer is PMMA, a strong dependence of the crystallizability of the copolymer on the molecular weight of the PTHF block is observed; the higher the molecular weight, then the stronger its crystallizability. The melting temperature of the block copolymer is dependent on the copolymer composition and the molecular weight of its crystallizable block. Copyright (C) 1996 Elsevier Science Ltd.

RADIATION-INDUCED CRYSTAL DEFECTS IN PTFE

Changes induced in the crystal structure of PTFE by irradiation at different temperatures have been investigated. In the dose and temperature range examined, the density of PTFE was observed to increase continuously with increasing dose due to the radiation-induced increase in crystallinity, while after post-irradiation annealing at 380-degrees-C, the density was observed to increase for samples irradiated at 20-degrees-C, and to begin to decrease after a certain dose for samples irradiated at 150 and 200-degrees-C. On the basis of the observation of radiation-induced separation of the melting peak of PTFE and its stability relative to the change in the rate of heating, the observed decrease in density was explained as being due to the radiation-induced crosslinking and/or branching inhibiting the process of crystallization and existing in the crystalline region as defects.

THE EFFECT OF RADIATION-INDUCED CROSS-LINKING ON THE RELAXATION OF TAUT TIE MOLECULES DURING ANNEALING OF DRAWN LDPE

Shrinkage, retractive stress, and infrared dichroism of the drawn low-density polyethylene (LDPE) as-drawn and irradiated by Co-60-ray have been measured under different annealing conditions. The shrinkage and the disorientation of the irradiated sample was undergone more rapidly than that of unirradiated one as the temperature was continuously increased, surpassing a certain value, and a higher degree of shrinkage and disorientation was achieved finally for the irradiated sample when the samples were annealed with free ends. For the samples heated isothermally with fixed ends, the retractive stress went through a maximum and then attenuated to a limited value, and the degree of such a stress attenuation for the unirradiated sample was much more than that for the irradiated sample. These results show that the taut tie molecules (TTMs) in drawn PE can relax by the pulling of chain segments out of crystal blocks that they anchored in at elevated temperatures higher than the a transition and also by the displacing of microfibrils if the samples were annealed with free ends. The cross-links produced by irradiation prohibit the former process. It was further observed that the dependence of the average extinction coefficient of the band at 2016 cm-1 on that of the band at 1894 cm-1 is related to irradiation and annealing conditions, which has also been explained by the relaxation of TTMs and the function of irradiation-induced cross-linking on the relaxation.

BLENDS OF PHENOLPHTHALEIN POLY(ETHER ETHER KETONE) WITH PHENOXY AND EPOXY-RESIN

The properties of miscible phenolphthalein poly(ether ether ketone)/phenoxy (PEK-C/phenoxy) blends have been measured by dynamic mechanical analysis and tensile testing. The blends were found to have single glass transition temperatures (T(g)) that vary continuously with composition. The tensile moduli exhibit positive deviations from simple additivity. Marked positive deviations were also observed for tensile strength. The tensile strengths of the 90/10 and 75/25 PEK-C/phenoxy blends are higher than those of both the pure components. Embrittlement, or transition from the brittle to the ductile mode of failure, occurs in the composition range of 50-25 wt% PEK-C. These observations suggest that mixing on the segmental level has occurred and that there is enough interaction between the components to decrease its internal mobility significantly. PEK-C was also found to be miscible with the epoxy monomer, diglycidyl ether of bisphenol A (DGEBA), as shown by the existence of a single glass transition temperature (T(g)) within the whole composition range. Miscibility between PEK-C and DGEBA could be considered to be due mainly to entropy. However, PEK-C was judged to be immiscible with the diaminodiphenylmethane-curved epoxy resin (DDM-cured ER). It was observed that the PEK-C/ER blends have two T(g), which remain invariant with composition and are almost the same as those of the pure components, respectively. Scanning electron microscopy showed that the PEK-C/ER blends have a two-phase structure. The different miscibility with PEK-C between DGEBA and the DDM-cured ER is considered to be due to the dramatic change in the chemical and physical nature of ER after curing.

Comparison of photobioreactors and optimal light regime for rapid vegetative propagation of transgenic Undaria pinnatifida gametophytes

BACKGROUND: Previously, tachyplesin gene (tac) has been successfully transferred into Undaria pinnatifida gametophytes using the method of microprojectile bombardment transformation. The objectives of this study were to compare and evaluate the performance of bubble-column and airlift bioreactors to determine a preferred configuration of bioreactor for vegetative propagation of transgenic U. pinnatifida gametophytes, and to then investigate the influence of light on vegetative propagation of these gametophytes, including incident light intensity, photoperiod and light quality to resolve the problems of rapid vegetative propagation within the selected bioreactor. RESULTS: Experimental results showed that final dry cell density in the airlift bioreactor was 12.7% higher than that in the bubble-column bioreactor under the optimal aeration rate of 1.2 L air min(-1) L-1 culture. And a maximum final dry cell density of 2830 mg L-1 was obtained within the airlift bioreactor using blue light at 40 mu mol m(-2) s(-1) with a light/dark cycle of 14/10 (h). Polymerase chain reaction (PCR) analysis indicated that genes (bar and tac) were not lost during rapid vegetative propagation within the airlift bioreactor. CONCLUSION: The airlift bioreactor was shown to be much more suitable for rapid vegetative propagation of transgenic U. pinnatifida gametophytes than the bubble-column bioreactor in the laboratory. The use of blue light allows improvement of vegetative propagation of transgenic U. pinnatifida gametophytes. (C) 2009 Society of Chemical Industry

Ontogenetic development of digestive enzymes and effect of starvation in miiuy croaker Miichthys miiuy larvae

The ontogenetic development of the digestive enzymes amylase, lipase, trypsin, and alkaline phosphatase and the effect of starvation in miiuy croaker Miichthys miiuy larvae were studied. The activities of these enzymes were detected prior to exogenous feeding, but their developmental patterns differed remarkably. Trypsin activity continuously increased from 2 days after hatching (dah), peaked on 20 dah, and decreased to 25 dah at weaning. Alkaline phosphatase activity oscillated at low levels within a small range after the first feeding on 3 dah. In contrast, amylase and lipase activities followed the general developmental pattern that has been characterized in fish larvae, with a succession of increases or decreases. Amylase, lipase, and trypsin activities generally started to increase or decrease at transitions from endogenous to exogenous feeding or diet changes, suggesting that these enzymatic activities can be modulated by feeding modes. The activities of all the enzymes remained stable from 25 dah onwards, coinciding with the formation of gastric glands and pyloric caecum. These results imply that specific activities of these enzymes underwent changes due to morphological and physiological modifications or diet shift during larval development but that they became stable after the development of the digestive organs and associated glands was fully completed and the organs/glands functioned. Trypsin and alkaline phosphatase were more sensitive to starvation than amylase and lipase because delayed feeding up to 2 days after mouth opening was able to adversely affect their activities. Enzyme activities did not significantly differ among feeding groups during endogenous feeding; however, all activities were remarkably reduced when delayed feeding was within 3 days after mouth opening. Initiation of larvae feeding should occur within 2 days after mouth opening so that good growth and survival can be obtained in the culture.

Suspension culture of gametophytes of transgenic kelp in a photobioreactor

Transgenic Laminaria japonica gametophytes producing a recombinant tissue-type plasminogen activator (rtPA) protein, which is an effective third-generation thrombolytic agent for acute myocardial infarction (AMI), were cultured in an illuminated bubble column bioreactor. A maximum final dry cell weight of 1120 mg l(-1) was obtained in batch culture with an initial dry cell weight of 126 mg l(-1) and with aeration rate of 1.2 l air min(-1) l(-1) culture, nitrate at 1.5 mM and phosphate at 0.17 mM. The yield of rtPA was 56 mu g g(-1) dry cell wt. This is the first report regarding cultivation of a transgenic macroalga in a bioreactor.