Kinetically Stable Bicelles with Dilution Tolerance,Size Tunability,and Thermoresponsiveness for Drug Delivery Applications

Mixtures of a phospholipid (1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphatidylcholine, DPPC) and a sodium‐cholate‐derived surfactant (SC‐C₅) at room temperature formed phospholipid bilayer fragments that were edge‐stabilized by SC‐C₅: so‐called “bicelles”. Because the bilayer melting point of DPPC (41 °C) is above room temperature and because SC‐C₅ has an exceptionally low critical micelle concentration (<0.5 mm ), the bicelles are kinetically frozen at room temperature. Consequently, they exist even when the mixture is diluted to a concentration of 0.04 wt %. In addition, the lateral size of the bicelles can be fine‐tuned by altering the molar ratio of DPPC to SC‐C₅. On heating to ≈37 °C, the bicelles transformed into micelles composed of DPPC and SC‐C₅. By taking advantage of the dilution tolerance, size tunability, and thermoresponsiveness, we demonstrated in vitro drug delivery based on use of the bicelles as carriers, which suggests their potential utility in transdermal drug delivery.     

Estimation of wood stiffness and strength properties of hybrid larch by near-infrared spectroscopy

This work was undertaken to investigate the feasibility of near-infrared (NIR) spectroscopy for estimating wood mechanical properties, i.e., modulus of elasticity (MOE) and modulus of rupture (MOR) in bending tests. Two sample sets having large and limited density variation were prepared to examine the effects of wood density on estimation of MOE and MOR by the NIR technique. Partial least squares (PLS) analysis was employed and it was found that the relationships between laboratory-measured and NIR-predicted values were good in the case of sample sets having large density variation. MOE could be estimated even when density variation in the sample set was limited. It was concluded that absorption bands due to the OH group in the semi-crystalline or crystalline regions of cellulose strongly influenced the calibrations for bending stiffness of hybrid larch. This was also suggested from the result that both alpha-cellulose content and cellulose crystallinity showed moderate positive correlation to wood stiffness.     

Production of extracellular bifidogenic growth stimulator by anaerobic and aerobic cultivations of several propionibacterial strains

Production of a bifidogenic growth stimulator (BGS) by propionic acid bacteria was investigated under anaerobic and aerobic culture conditions. To measure the concentration of extracellular BGS produced by propionic acid bacteria, we evaluated the effects of bioassay conditions using Bifidobacterium longum as a test microorganism on the formation of a growth-stimulation zone. The diameter of the growth-stimulation zone was significantly affected by both the component concentrations and the pH of a bioassay medium. The optimum component concentrations and pH of a bioassay medium were one-half of the normal values and 8.5, respectively. Using the bioassay method, we can measure the concentration of BGS produced by propionic acid bacteria ranging in concentrations from 0.1 microg/l to 1 mg/l using 1,4-dihydroxy-2-naphthoic acid (DHNA) and 2-amino-3-carboxy-1,4-naphthoquinone (ACNQ) as standards. Of six dairy propionic acid bacterial strains tested, the four strains (Propionibacterium freudenreichii ET-3, P. shermanii PZ-3, P. acidipropionici JCM 6432, and P. jensenii JCM 6433) produced BGS at a concentration range of 4-23 mg/l under the anaerobic culture conditions. Analysis of high performance liquid chromatography (HPLC) showed that more than 70% of total BGS produced in supernatant samples was DHNA and no ACNQ was produced by the strains. The effect of oxygen supply on BGS production was investigated for the four BGS-producing strains. The aerobic conditions exerted in positive effects on BGS production by only P. acidipropionici JCM 6432. The concentration of BGS obtained in the aerobic cultivation of P. acidipropionici JCM 6432 was 1.3-fold than that in anaerobic cultivation. Different properties (BGS production as well as cell growth and glucose metabolism) occurring in response to the aerobic conditions were observed, depending on the propionic acid bacterial strain used. This paper is the first report on BGS production by propionibacterial strains except for P. freudenreichii.     

Purification and some properties of beta-fructofuranosidase I formed by Aureobasidium pullulans DSM 2404

beta-Fructofuranosidase I (FFase I) formed by Aureobasidium pullulans DSM 2404 was purified. The enzyme had a molecular weight of about 430 kDa, was not affected by various metal ions and showed high transfructosylating activity. The yield of fructooligosaccharides production using purified FFase I was 62%.     

Electron beam nanoprocessing of a carbon nanotube film using a variable pressure scanning electron microscope

We demonstrate a novel method of processing carbon nanotubes using a variable pressure scanning electron microscope. Lines were processed in a nanotube film by electron beam irradiation in oxygen gas and nitrogen gas. The processing mechanism can be explained in terms of gas ion sputtering and chemical reaction. In this experiment, the narrowest line width of 120 nm was achieved in a nitrogen atmosphere.     

High-efficiency InGaP/In0.01Ga0.99As tandem solar cells lattice-matched to Ge substrates

Conversion efficiency (AM1.5G) of more than 30% was achieved by adding a small quantity of Indium into a GaAs bottom cell in the conventional tandem solar cell on Ge substrate. It was found that the lattice-mismatch between GaAs and Ge caused misfit-dislocations in thick GaAs layers and reduced an open-circuit voltage (V_oc) of the cell. An In_0.49Ga_0.51P/In_0.01Ga_0.99As tandem cell lattice-matched to Ge showed a great improvement in efficiency, which was attributed to an increase in the V_oc of the bottom cell and increases in the photocurrents both in the top and bottom cells due to reductions in band-gap energy.     

Characterization of phospholipid reverse micelles in relation to membrane processing of vegetable oils

Studies were conducted to determine the critical micelle concentration (CMC) of phospholipids in vegetable oils and the size of reverse micelles to understand their rejection phenomenon in the membrane process. The CMC values of phosphatidylcholine (PC) in triolein and phospholipids in crude soybean oil were determined to be 440 and 1020 mg/kg, respectively, by using TCNQ (7,7,8,8‐tetracyano‐quinodimethane) solubilization technique. The surface tension measurements of these samples gave similar values of CMC. From small‐angle X‐ray scattering (SAXS) analysis, the size of the PC micelles was determined to be in the range of 3.56 to 4.70 nm. The characterization of reverse micelles formed in the oil system was found useful in enhancing the understanding of the possible rejection phenomenon of phospholipids by non‐porous polymeric composite membranes used in our earlier studies on vegetable oils and in suggesting suitable types of membranes for the same.     

High-pressure synthesis and optical limiting property of cyclic diphenylacetylene oligomer

New conjugated oligomers were synthesized by reacting diphenylacetylene under high pressure of 0.13–0.76 GPa at 250 and 300°C for 1–10 h. The number-average molecular weight M _n, and the weight-average molecular weight M _w increased with pressure, but those values were independent of temperature and time (M _n, 320–490; M _w, 350–580). Elementary analysis, field desorption mass spectrometry, Fourier transform infrared, and ¹³C nuclear magnetic resonance experiments revealed that the oligomer above and including pentamer was a new compound having cyclic structure. Toluene solutions of the oligomer (400 M _n) contained within a quartz cell were irradiated with the pulse from a frequency-doubled Nd : Yag laser at 532 nm. The transmittance of the solution decreased with input fluence, and we observed an optical limiting property with saturated output fluence. As the concentration of the oligomer increased, the saturated output fluence decreased. The optical limiting property was analyzed according to the reverse saturable absorption mechanism. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:129–135, 1998