Directional Self‐Assembly of Fluorinated Star Block Polymer Thin Films Using Mixed Solvent Vapor Annealing

We demonstrate the directional alignment of perpendicular‐lamellae domains in fluorinated three‐armed star block polymer (BP) thin films using solvent vapor annealing with shear stress. The control of orientation and alignment was accomplished without any substrate surface modification. Additionally, three‐armed star poly(methyl methacrylate‐block‐styrene) [PMMA‐PS] and poly(octafluoropentyl methacrylate‐block‐styrene) were compared to their linear analogues to examine the impact of fluorine content and star architecture on self‐assembled BP feature sizes and interdomain density profiles. X‐ray reflectometry results indicated that the star BP molecular architecture increased the effective polymer segregation strength and could possibly facilitate reduced polymer domain spacings, which are useful in next‐generation nanolithographic applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1663–1672     

Development of an efficient amine-functionalized glass platform by additional silanization treatment with alkylsilane

Aminosilane-treated molecular layers on glass surfaces are frequently used as functional platforms for biosensor preparation. All the amino groups present on the surface are not available in reactive forms, because surface amino groups interact with remaining unreacted surface silanol groups. Such nonspecific interactions might reduce the efficiency of chemical immobilization of biomolecules such as DNA, enzymes, antibodies, etc., in biosensor fabrication. To improve immobilization efficiency we have used additional surface silanization with alkylsilane (capping) to convert the remaining silanol groups into Si–O–Si linkages, thereby liberating the amino groups from nonspecific interaction with the silanol groups. We prepared different types of capped amine surface and evaluated the effect of capping on immobilization efficiency by investigating the fluorescence intensity of Cy3-NHS (N-hydroxysuccinimide) dye that reacted with amino groups. The results indicate that most of the capped amine surfaces resulted in enhanced efficiency of immobilization of Cy3-NHS compared with the untreated control amine surface. We found a trend that trialkoxysilanes had greater capping effects on immobilization efficiency than monoalkoxysilanes. It was also found that the aliphatic chain of alkylsilane, which does not participate in the capping of the silanol, had an important function in enhancing immobilization efficiency. These results would be useful for preparation of an amine-modified surface platform, with enhanced immobilization efficiency, which is essential for developing many kinds of biosensors on a silica matrix. Enhancement of amine funtionality by capping with alkylsilane     

Sequential actions of cobalt nanoparticles and palladium(II) catalysts: three-step one-pot synthesis of fenestranes from an enyne and an alkyne diester

A three-step one-pot synthesis of fenestranes from a readily available enyne and an alkyne diester has been carried out with cobalt nanoparticles and palladium(II) as catalysts.     

Development of a simultaneous analytical method for selected anorectics,methamphetamine, MDMA,and their metabolites in hair using LC-MS/MS to prove anorectics abuse

Owing to the tight control of methamphetamine, it is presumed that phentermine, an amphetamine-type anorectic, has recently been considered a supplement for methamphetamine abusers in Korea. In addition, the abuse of other anorectics obtained by inappropriate means has become a social issue. Hair is a useful specimen to prove chronic drug use. Therefore, an analytical method for the simultaneous detection of phentermine, phendimetrazine, amfepramone, fenfluramine, mazindol, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA), as well as their metabolites, which covers the major amphetamines and anorectic agents in Korea, in hair was established and validated using liquid chromatography–tandem mass spectrometry (LC-MS/MS). The drugs and their metabolites in hair were extracted using 1 % HCl in methanol and then filtered and analyzed by LC-MS/MS with electrospray ionization in positive mode. The validation results for selectivity, linearity, matrix effect, recovery, process efficiency, intra- and interassay precision and accuracy, and processed sample stability were satisfactory. The limits of detection ranged from 0.025 to 1 ng/10 mg hair and the limits of quantification were 0.25 ng/10 mg hair for every analyte except mazindol and phentermine, for which they were 10 ng/10 mg hair. The method was successfully applied for the segmental determination of selected anorectics, methamphetamine, MDMA, and their metabolites in hair from 39 drug suspects. Among the anorectics, phentermine and/or phendimetrazine were identified with or without methamphetamine in the hair samples. Closer supervision of the inappropriate use of anorectics is necessary. Also, hair analysis is useful for monitoring the abuse potential of unnoticed drugs.     

Amide-based nonheme cobalt(III) olefin epoxidation catalyst: partition of multiple active oxidants Co(V)=O, Co(IV)=O, and Co(III)-OO(O)CR

A mononuclear nonheme cobalt(III) complex of a tetradentate ligand containing two deprotonated amide moieties, [Co(bpc)Cl(2)][Et(4)N] (1; H(2)bpc = 4,5-dichloro-1,2-bis(2-pyridine-2-carboxamido)benzene), was prepared and then characterized by elemental analysis, IR, UV/Vis, and EPR spectroscopy, and X-ray crystallography. This nonheme Co(III) complex catalyzes olefin epoxidation upon treatment with meta-chloroperbenzoic acid. It is proposed that complex 1 shows partitioning between the heterolytic and homolytic cleavage of an O-O bond to afford Co(V)=O (3) and Co(IV)=O (4) intermediates, proposed to be responsible for the stereospecific olefin epoxidation and radical-type oxidations, respectively. Moreover, under extreme conditions, in which the concentration of an active substrate is very high, the Co-OOC(O)R (2) species is a possible reactive species for epoxidation. Furthermore, partitioning between heterolysis and homolysis of the O-O bond of the intermediate 2 might be very sensitive to the nature of the solvent, and the O-O bond of the Co-OOC(O)R species might proceed predominantly by heterolytic cleavage, even in the presence of small amounts of protic solvent, to produce a discrete Co(V) ?O intermediate as the dominant reactive species. Evidence for these multiple active oxidants was derived from product analysis, the use of peroxyphenylacetic acid as the peracid, and EPR measurements. The results suggest that a less accessible Co(V)=O moiety can form in a system in which the supporting chelate ligand comprises a mixture of neutral and anionic nitrogen donors.     

Determination and pharmacokinetics of [6]-gingerol in mouse plasma by liquid chromatography-tandem mass spectrometry

This study describes the development of a rapid and sensitive high‐performance liquid chromatography–electrospray ionization tandem mass spectrometry (LC‐MS/MS) assay for the quantification of [6]‐gingerol in mouse plasma and application to a pharmacokinetic study after dose ranging in mice. The assay involved a protein precipitation step with acetonitrile and an isocratic elution using a mobile phase consisting of acetonitrile and water containing 0.1% formic acid (80:20 v/v). The multiple reaction monitoring was based on the transition of m/z = 277.2 → 177.1 for [6]‐gingerol and 294.2 → 137.1 for nonivamide (internal standard). The assay was validated to demonstrate the specificity, linearity, recovery, accuracy, precision and stability. The calibration curves were linear over the wide concentration range of 10–10,000 ng/mL (r ≥ 0.9988). The lower limit of quantification was 10 ng/mL using a small volume of mouse plasma (20 μL). The method was successfully applied to a pharmacokinetic study in mice after intravenous injection of [6]‐gingerol at 1.5, 3 and 6 mg/kg doses. The pharmacokinetics of [6]‐gingerol were linear over the dose range studied as demonstrated by the linear increase in area under the concentration‐time curve (AUC_inf) with no significant change in the systemic clearance (Cl_s), volume of distribution (V_ss) and elimination half‐life (t_1/2) as a function of dose. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of plasma etching on photoluminescence of SnO(x)/Sn nanoparticles deposited on DOPC lipid membrane

The photoluminescence characteristic of the SnO(x)/Sn nanoparticles deposited on a solid supported liquid-crystalline phospholipid (1,2-dioleoyl-sn-glycero-3-phosphocholine) membrane was probed after plasma etching the nanoparticle monolayer. It was shown that the plasma etching of the nanoparticle surface greatly altered the particle morphology and enhanced the PL effect, especially when the particle size was below 10 nm in spite of strong presence of surrounding carbon. The enhancement mainly stemmed from the growth of a new PL peak due to the additional defect states produced on the nanoparticle surface by the plasma etching. It was also shown that hydrating the SnO(x)/Sn nanoparticles similarly improved the PL response of the nanoparticles as the hydration produced an additional oxygen-rich oxide layer on the particle surface.     

On-chip continuous monitoring of motile microorganisms on an ePetri platform

Self-imaging Petri dish platforms with microscopy resolution, which we term 'ePetri', can significantly streamline cell cultures and/or other longitudinal biological studies. In this paper, we demonstrate high-resolution imaging and long-term culture of motile microorganisms in a specialized ePetri platform by taking advantage of the inherent motion. By applying a super-resolution algorithm to a set of low-resolution images of the microorganisms as they move across the sensing area of a complementary metal oxide semiconductor (CMOS) image sensor chip, we can render an improved-resolution image of the microorganisms. We perform a longitudinal study of Euglena gracilis cultured in an ePetri platform, and image-based analysis on the motion and morphology of the cells. As a miniaturized and automated culture monitoring platform, this ePetri technology can greatly improve studies and experiments with motile microorganisms.     

Surface-dependent, ligand-mediated photochemical etching of CdSe nanoplatelets

Photochemical etching of CdSe nanoplatelets was studied to establish a relationship between the nanocrystal surface and the photochemical activity of an exciton. Nanoplatelets were synthesized in a mixture of octylamine and oleylamine for the wurtzite (W) lattice or in octadecene containing oleic acid for the zinc-blende (ZB) lattice. For photochemical etching, nanoplatelets were dispersed in chloroform containing oleylamine and tributylphosphine in the absence or presence of oleic acid and then irradiated with light at the band-edge absorption maxima. Etching phenomena were characterized using UV-vis absorption spectroscopy and transmission electron microscopy. The absorption spectra of both W and ZB CdSe nanoplatelets showed that the exciton was confined in one dimension along the thickness. However, the two nanoplatelets presented different etching kinetics and erosion patterns. The rate of etching for W CdSe nanoplatelets was much faster than that for ZB nanoplatelets. Small holes were uniformly perforated on the planar surface of W nanoplatelets, whereas the corners and edges of ZB nanoplatelets were massively eroded without a significant perforation on the planar surface. This suggests that the amine-passivated surface of trivalent cadmium atoms on CdSe nanoplatelets is photochemically active, but the carboxylate-passivated surface of divalent cadmium atoms is not. Hence, the ligand, which induces the growth of W or ZB CdSe nanoplatelets, mediates the surface-dependent photochemical etching. This result implies that an electron-hole pair can be extracted from the planar surface of amine-passivated W nanoplatelets but from the corners and edges of carboxylate-passivated ZB nanoplatelets.     

Preparation of ω-tetrahydropyran-2-ylsulfanylalkylmagnesium chlorides: Useful reagents for the synthesis of 1-(ω-mercaptoalkyl)-1,2-dihydrobuckminsterfullerenes (C60)

ω-Tetrahydropyran-2-ylsulfanylalkylmagnesium chlorides are prepared as Grignard reagents containing protected mercaptoalkyl chains, which are useful for the direct introduction of ω-mercaptoalkyl chains to electrophiles. In order to prove the usefulness of these reagents, they were reacted with buckminsterfullerene (C₆₀) to give 1-(ω-mercaptoalkyl)-1,2-dihydrobuck minsterfullerenes after the deprotection of THP group with TFA.