Continuous fabrication of biocatalyst immobilized microparticles using photopolymerization and immiscible liquids in microfluidic systems

We report a novel technique for manufacturing polymeric microparticles containing biocatalysts by the behavior of immiscible liquids in microfluidic systems and in situ photopolymerization. The approach utilizes a UV-polymerizable hydrogel/enzyme solution and an immiscible oil solution. The oil and hydrogel solutions form emulsions in pressure-driven flow in microchannels at high values of the dimensionless capillary number (Ca). The resultant hydrogel droplets are then polymerized in situ via exposure to 365 nm UV light. This technique allows for the generation of monodisperse particles whose size can be controlled by the regulation of flow rates. In addition, both manufacturing microparticles and immobilizing biocatalysts can be performed simultaneously and continuously.     

Quantitative measurement of male steroid hormones using automated on-line solid phase extraction-liquid chromatography-tandem mass spectrometry and comparison with radioimmunoassay

A specific and sensitive method using high-performance liquid chromatography-tandem mass spectrometry (LC-MS-MS) equipped with automatic on-line solid-phase extraction device for the quantitative measurement of anabolic hormone residues, 4-androstene-3,17-dione, testosterone and dihydrotestosterone in cell culture medium was developed. Steroid content in cell culture medium was determined directly without an additional sample preparation step. Separation of analytes from polar endogenous compounds was carried out on an automatic column-switching device coupled with a C4-alkyl-diol silica restricted-access solid-phase extraction column. The lipophilic fraction containing anabolic hormone residues were back-flushed on to a conventional C-18 reversed-phase column for the final chromatography. The analyte was ionized in an ElectroSpray interface under positive ion mode before entering a quadrupole mass analyzer. The lowest points of calibration curves were 0.05 ng ml(-1) for 4-androstene-3,17-dione and testosterone, and 1 ng ml(-1) dihydrotestosterone, respectively. A comparison with results from radioimmunoassay (RIA) is also presented.     

Carbon skeletal rearrangement and hydrogen migration in thiophene

The mass spectra of ¹³C-labelled thiophenes were studied and the label-distributions for the C₃H₃⊕, HCS⊕, C₂H₂S⊕ and [M ? CH₃]⊕ ions are interpreted in terms of a carbon skeletal rearrangement. From a comparison of the results of ¹³C-labelling and D-labelling, a concurrent hydrogen migration process is demonstrated. The production of HCS⊕ ions is preceded by partial carbon scrambling and hydrogen migration is of minor importance. In contrast, hydrogen scrambling predominates over carbon scrambling in the loss of acetylene.     

Liquid Nickel Salts: Synthesis,Crystal Structure Determination,and Electrochemical Synthesis of Nickel Nanoparticles

New nickel‐containing ionic liquids were synthesized, characterized and their electrochemistry was investigated. In addition, a mechanism for the electrochemical synthesis of nanoparticles from these compounds is proposed. In these so‐called liquid metal salts, the nickel(II) cation is octahedrally coordinated by six N‐alkylimidazole ligands. The different counter anions that were used are bis(trifluoromethanesulfonyl)imide (Tf₂N^?), trifluoromethanesulfonate (OTf^?) and methanesulfonate (OMs^?). Several different N‐alkylimidazoles were considered, with the alkyl sidechain ranging in length from methyl to dodecyl. The newly synthesized liquid metal salts were characterized by CHN analysis, FTIR, DSC, TGA and viscosity measurements. An odd‐even effect was observed for the melting temperatures and viscosities of the ionic liquids, with the complexes with an even number of carbon atoms in the alkyl chain of the imidazole having a higher melting temperature and a lower viscosity than the complexes with an odd number of carbons. The crystal structures of several of the nickel(II) complexes that are not liquid at room temperature were determined. The electrochemistry of the compounds with the lowest viscosities was investigated. The nickel(II) cation could be reduced but surprisingly no nickel deposits were obtained on the electrode. Instead, nickel nanoparticles were formed at 100 % selectivity, as confirmed by TEM. The magnetic properties of these nanoparticles were investigated by SQUID measurements.     

Complexation and Sensing Behavior of Dansyl-appended Cyclodextrins and Cyclodextrin Dimers with Bile Salts

The dansyl-modified cyclodextrin derivatives 2 and 3 form complexes with the steroidal bile salts. The selectivity of the monomeric derivative 3 is similar to that of native g -cyclodextrin. All binding constants with 3 are lowered compared to g -cyclodextrin because of the competition for the cavity between the steroids and the dansyl moiety. Cholate ( 4a ) and deoxycholate ( 4b ) form weak complexes, the other bile salts ( 4c - e ) are complexed far more strongly. The difference is attributed to the absence of a 12-hydroxy group in the latter steroids. Data for dimer 2 reveal strongly enhanced binding of 4a and 4b and only slightly stronger complexes with the other steroids. Due to the low binding affinity of 3 for 4a and 4b , this receptor could not be used for their detection by fluorescence spectroscopy. Steroids 4c - e showed a decrease in fluorescence intensity. The detection of all steroids 4a - e was possible using 2 . The fluorescence intensity of the dimer increased or decreased, depending on which steroid was added.     

Eumelanin as a support for efficient palladium nanoparticle catalyst for Suzuki coupling reaction of aryl chlorides in water

Eumelanin-supported palladium (Pd) nanoparticle (NP) catalysts was found to exhibit excellent catalytic activities with high turnover number (TON, 2000) and turnover frequency (TOF, 1000 h^?1) for Suzuki cross coupling reaction of aryl chlorides in water. We propose that the amphiphilic property of the eumelanin support helps Pd NPs to catalyse the C–C coupling reaction in water through hydrophobic effect.     

Covalent fixed multicyclic polystyrene conformers

Covalent fixed multicyclic polystyrene conformers were synthesized from inconvertible polystyrene conformers based on p‐tert‐butylthiacalix[4]arene by azidation and subsequent click coupling. Selective 1D NOESY analyses confirmed that the spatial structures of star polystyrene precursors and multicyclic polystyrenes were preserved during the azidation and click coupling processes. The conformation of star polymers affected degree of decrease in the hydrodynamic volume after cyclization but had little effect on glass transition behavior. The rigid core of star polymer increased the T_g but in the case of multicyclic polymer, this influence of core structure was reduced. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 4020–4026     

Functional fuzzy clusterwise regression analysis

We propose a functional extension of fuzzy clusterwise regression, which estimates fuzzy memberships of clusters and regression coefficient functions for each cluster simultaneously. The proposed method permits dependent and/or predictor variables to be functional, varying over time, space, and other continua. The fuzzy memberships and clusterwise regression coefficient functions are estimated by minimizing an objective function that adopts a basis function expansion approach to approximating functional data. An alternating least squares algorithm is developed to minimize the objective function. We conduct simulation studies to demonstrate the superior performance of the proposed method compared to its non-functional counterpart and to examine the performance of various cluster validity measures for selecting the optimal number of clusters. We apply the proposed method to real datasets to illustrate the empirical usefulness of the proposed method.     

Quantitation of plasma and biliary cefpiramide concentrations in human samples using high-performance liquid chromatography

Cefpiramide is frequently used to treat biliary infections. However, no bioanalytical method has been validated to quantitate cefpiramide in human samples, particularly in bile. Therefore, this study was conducted to develop a simple, selective and validated high-performance liquid chromatographic method to determine cefpiramide in human plasma and bile. A protein precipitation procedure was used to extract cefpiramide and cefoperazone (internal standard, IS) from 200 μl of plasma and bile. Utilizing a Capcell Pak C₁₈ column (4.6 × 250 mm), cefpiramide and IS were separated using the timed-gradient mobile phase consisting of 0.1 m sodium acetate (pH 5.2) and acetonitrile at a flow rate of 1 ml/min with photodiode array detector (wavelength set at 273 nm). The calibration curves showed linearity at concentrations ranging from 1 to 150 μg/ml in both plasma and bile (r² > 0.999). The within- and between-run coefficients of variation (CVs) for plasma samples were 0.570–4.43 and 1.10–2.76%, respectively; for bile samples, the within- and between-day precision (CV) was 0.814–6.34 and 2.05–4.00%, respectively. Our newly developed bioanalytical method was successfully employed to quantify cefpiramide concentrations in both plasma and bile at multiple time points in patients with acute cholangitis.     

Efficient energy transfer between amphiphilic dendrimers with oligo(p‐phenylenevinylene) core branches and oligo(ethylene oxide) termini in micelles

The efficient fluorescence resonance energy transfer (FRET) between amphiphilic dendrimers with oligo(p‐phenylenevinylene) core branches and oligo(ethylene oxide) termini have been observed in micelles. All dendrimers show the critical micelle concentration and lower critical solution temperature as well as fluorescent emission. Tailoring electronic structures of the conjugated amphiphiles for FRET have been conveniently achieved by varying the branch number and/or the conjugated core structure. The Stern‐Volmer constants (K_SV) for FRET were found to be 4.51 × 10^?5 and 8.78 × 10^?5 M for Den 30–40 and Den 50–40, respectively. The effects external stimuli such as solvent and temperature on FRET have been also investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013