Photoinduced phospholipid polymer grafting on Parylene film: advanced lubrication and antibiofouling properties

Poly(p-xylylene) (Parylene C) coatings have been applied in implantable electronic devices because of their electrical insulation and moisture barrier properties. To provide lubrication and an antibiofouling surface, a biomimetic phospholipid polymer--poly(2-methacryloyloxyethyl phosphorylcholine (MPC))--was grafted from the surface using UV irradiation with benzophenone as an initiator. The poly(MPC) grafting on the Parylene C films was confirmed by attenuated total reflection-Fourier transfer inflated irradiation, X-ray photoelectron spectroscopy and ellipsometry. These analyses indicated that the Parylene C films were completely covered by the poly(MPC)-graft layer with an average thickness of 140 nm under dry condition. The atomic force microscope (AFM) images revealed that the poly(MPC)-graft chains extended under wet condition. However, they formed globular structures under dry condition. Water contact angle measurements revealed a decreased receding angle of 29.5 degrees on the poly(MPC)-grafted surface with a high hysteresis of 41.4 degrees. These results indicate that the poly(MPC)-graft chains gain mobility in a wet environment. The average kinetic friction coefficient of the poly(MPC)-grafted surface in water was 0.018, which was 90% lower than that of the original surface. The in vitro single protein adsorption reduced by over 70% due to the poly(MPC) grafting. The hydrated poly(MPC)-graft chains are considered to provide lubrication and antibiofouling properties. The surface zeta potential measurement clarified the electroneutrality of the poly(MPC)-grafted surface. We concluded that the poly(MPC) grafting from the Parylene C layer significantly improved its surface properties and, subsequently, its biological properties.     

Lignocellulose - polymer composites

Water hyacinth and its mechanical pulps were used as lignocellulose to produce composites together with polystyrene or urea-formaldehyde resins. The bending strength of the composites increased with increasing concentration of the resin. The temperatures of the treatment of water hyacinth to obtain the pulps affect the strength and densities of the composites. This may be attributed to the behavior of lignin at temperatures higher than 135°C. The composites produced using urea-formaldehyde resins showed slight increase in bending strengths compared with those produced using polystyrene, which may be attributed to the ability of formaldehyde to make crosslinks with the free OH groups of cellulose and hemicellulose. Contrary to water hyacinth, the use of ground palm leaves together with 10% urea-formaldehyde resin produced composite with high density and low bending strength, while the ground water hyacinth failed. The pulp from palm leaves when processed into composites using 10% urea-formaldehyde resin show bending and densities affected by its preparation and by the amount of the composite mixture to be pressed. Hence the type of the substrate defined the type of the polymers or resin used to obtain composites with proper mechanical properties. The effect of the pressure used to produce composites from ground palm leaves or their pulp together with polystyrene was investigated. Linear relationships between the bending strength and pressure were obtained, the bending strength and densities increasing with increasing pressure. Thus, the increased pressures enhance mechanical properties of the composites.     

Two phenylpropanoid glycosides from Neopicrorhiza scrophulariiflora

Two new phenylpropanoid glycosides, scrophulosides A (1) and B (2), were isolated from the rhizomes of Neopicrorhiza scrophulariiflora (Scrophulariaceae), along with two known compounds, androsin (3) and picroside I. Their structures were elucidated on the basis of both chemical and spectroscopic data.     

HPLC enantioseparation of α,α‐diphenyl‐2‐pyrrolidinemethanol and methylphenidate using a chiral fluorescent derivatization reagent and its application to the analysis of rat plasma

Enantioseparation of α,α‐diphenyl‐2‐pyrrolidinemethanol (D2PM) and methylphenidate (MPH; Ritalin^®) using (R)‐(?)‐4‐(N,N‐dimethylaminosulfonyl)‐7‐(3‐isothiocyanatopyrrolidin‐1‐yl)‐2,1,3‐benzoxadiazole as the chiral derivatization reagent has been achieved for the first time, and a simple, reliable detection method using HPLC with fluorescence detection has been developed. D2PM and MPH have been derivatized with (R)‐(?)‐4‐(N,N‐dimethylaminosulfonyl)‐7‐(3‐isothiocyanatopyrrolidin‐1‐yl)‐2,1,3‐benzoxadiazole at 55°C for 15 min. The derivatives of D2PM and MPH have been separated, completely and rapidly, using a reversed‐phase system within 16 min (resolution factor (R_s)=1.60 and 2.53, respectively). The detection limits of (R)‐ and (S)‐D2PM were found to be 6.8 and 13 ng/mL, respectively, and those of D ‐ and L ‐threo‐MPH were 61 and 66 ng/mL, respectively (S/N=3). The proposed method was successfully applied to the analysis of rat plasma, where the rats were separately dosed with D2PM and MPH (Ritalin).     

Optimal Order Quadrature Error Bounds for Infinite-Dimensional Higher-Order Digital Sequences

Quasi-Monte Carlo (QMC) quadrature rules using higher-order digital nets and sequences have been shown to achieve the almost optimal rate of convergence of the worst-case error in Sobolev spaces of arbitrary fixed smoothness \(\alpha \in \mathbb {N}\), \(\alpha \ge 2\). In a recent paper by the authors, it was proved that randomly digitally shifted order \(2\alpha \) digital nets in prime base b achieve the best possible rate of convergence of the root mean square worst-case error of order \(N^{-\alpha }(\log N)^{(s-1)/2}\) for \(N=b^m\), where N and s denote the number of points and the dimension, respectively, which implies the existence of an optimal order QMC rule. More recently, the authors provided an explicit construction of such an optimal order QMC rule by using Chen–Skriganov’s digital nets in conjunction with Dick’s digit interlacing composition. These results were for fixed number of points. In this paper, we give a more general result on an explicit construction of optimal order QMC rules for arbitrary fixed smoothness \(\alpha \in \mathbb {N}\) including the endpoint case \(\alpha =1\). That is, we prove that the projection of any infinite-dimensional order \(2\alpha +1\) digital sequence in prime base b onto the first s coordinates achieves the best possible rate of convergence of the worst-case error of order \(N^{-\alpha }(\log N)^{(s-1)/2}\) for \(N=b^m\). The explicit construction presented in this paper is not only easy to implement but also extensible in both N and s.     

Simultaneous and group determination methods for designated substances by HPLC with multi-channel electrochemical detection and their application to real samples

Many psychotropic substances are illegally available on the streets and/or via the Internet. This wide distribution has become a serious social problem. To control this problem, many substances have been controlled as ‘designated substances’ (Shitei‐Yakubutsu) in Japan since April 2007 by the Pharmaceutical Affairs Law, including tryptamines, phenethylamines and piperazines. In the present study, simultaneous determination methods using HPLC with multi‐channel electrochemical detection (MECD) were developed for the designated substances. The proposed methods utilizing online electrochemical oxidation are the first report on the simultaneous determination of various designated substances. The methods involve direct determination and require no complicated pretreatments such as fluorescence labeling. The designated substances were separated by reversed‐phase chromatography using a TSK‐gel ODS‐100V (4.6 × 250 mm, i.d., 3 µm) and gradient elution by a mixture of potassium phosphate buffer, methanol and acetonitrile. The total separation of 31 designated substances was successfully performed but required long chromatographic run times. Thus, the designated substances were divided into three groups: (1) tryptamines, (2) phenethylamines and (3) piperazines and others. They were then analyzed by HPLC‐MECD as another separation method. The suitable applied voltages for each designated substance were determined based upon the hydrodynamic voltammogram. The limits of detection (signal‐to‐noise ratio of 3) of the designated substances for the most suitable voltages were in the range of 17.1 pg (5‐MeO‐MIPT) to 117 ng (indan‐2‐amine). The calibration curves based on the peak heights were linearly related to the amounts of the designated substances (R² > 0.999). Good accuracy and precision by intra‐day assay and inter‐day assay were also obtained using the present procedures. The proposed methods were applied to the analyses of the designated substance in several real samples. Copyright © 2010 John Wiley & Sons, Ltd.     

Highly efficient dynamic modification of plastic microfluidic devices using proteins in microchip capillary electrophoresis

New dynamic coating agents were investigated for the manipulation of electroosmotic flow (EOF) in poly(methylmethacrylate) (PMMA) microchips. Blocking proteins designed for enzyme-linked immunosorbent assay (ELISA) applications (e.g. Block Ace and UltraBlock), and egg-white lysozyme were proposed in this study. The EOF could be enhanced, suppressed or its direction could be reversed, depending on the buffer pH and the charge on the proteins. The coating procedure is simple, requiring only filling of the microchannels with a coating solution, followed by a rinse with a running buffer solution prior to analysis. One major advantage of this method is that it is not necessary to add the coating agent to the running buffer solution. Block Ace and UltraBlock coatings were stable for at least five runs in a given microchannel without the need to condition the coating between runs other than replenishing the buffer solution after each run, i.e. the RSD values of EOF (n=5) were less than 4.3%, and there was no significant change in the EOF after 5 runs. The reproducibility of the coating procedures was found from the channel-to-channel RSD values of the EOF, and were less than 5.0% when using HEPES-Na buffer (pH 7.4) as the running buffer. Several examples of electrophoretic separations of amino acids and biogenic amines derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) are demonstrated in this paper. The dynamic coating method has the potential for a broad range of applications in microchip capillary electrophoresis (microchip CE) separations.     

Optofluidic time-stretch microscopy: recent advances

Optical Review - Flow cytometry is an indispensable method for valuable applications in numerous fields such as immunology, pathology, pharmacology, molecular biology, and marine biology....     

Efficient Microwave‐Assisted Synthesis of 9,9‐Bis[4‐(2‐hydroxyethoxy)phenyl]fluorene from 9‐Fluorenone and 2‐Phenoxyethanol

9‐Fluorenone (1) smoothly reacts with phenoxyethanol (2) in the presence of Al³⁺‐montmorillonite catalyst and 3‐mercaptopropionic acid as a cocatalyst under microwave irradiation at 160°C for 10 min to give 9,9‐bis[4‐(2‐hydroxyethoxy)phenyl]fluorene (3) in 81% yield, which was much higher than the yield of 33% obtained by conventional heating using an oil bath. A similar acceleration effect of microwave irradiation was observed in other metal‐cation‐exchanged montmorillonite catalysts as well.     

Reaction of arynes with amino acid esters

An efficient route to a variety of 2-phenylindolin-3-ones from amino acid methyl esters has been developed. The reaction of amino acid methyl esters with benzyne prepared from 2-(trimethylsilyl)phenyl triflate and CsF gave 2-phenylindolin-3-ones in moderate to good yields.