An Ethylenediamine‐based Switch to Render the Polyzwitterion Cationic at Tumorous pH for Effective Tumor Accumulation of Coated Nanomaterials

Polyzwitterions are employed as coating polymers for biomaterials to induce an antifouling property on the surface. Fine‐tuning the betaine structure switches the antifouling property to be interactive with anionic tissue constituents in response to a tumorous pH gradient. The ethylenediamine moiety in the carboxybetaine enabled stepwise protonation and initiated the di‐protonation process around tumorous pH (6.5). The net charge of the developed polyzwitterion (PGlu(DET‐Car)) was thus neutral at pH 7.4 for antifouling, but was cationic at pH 6.5 for interaction with anionic constituents. Quantum dots coated with PGlu(DET‐Car) exhibited comparable stealth and enhanced tumor accumulation relative to the PEG system. The present study provides a novel design of smart switchable polyzwitterion based on a precise control of the net charge.     

Thermal polymerizations of alkali 4-(2-bromoethyl)benzoates in bulk

Thermal polymerizations of alkali 4-(2-bromoethyl)benzoates (2-BEBAs) were investigated. The polymerization of the lithium salt at 220°C for 2 h under reduced pressure in bulk, followed by esterification, produced poly(methyl 4-vinylbenzoate), having a number-average molecular weight (M̄_n) of 9500 in a 54% yield. Thus, elimination of hydrogen bromide to form a double bond occurred, followed by vinyl polymerization. In contrast, polymerization of the potassium salt at 200°C for 2 h afforded poly(oxycarbonyl-1,4-phenylene-ethylene) (polyester 1), having an inherent viscosity of 0.19 dL g⁻¹ in a 95% yield: i.e., polycondensation proceeded to afford the polyester. Reaction of the sodium salt at 220°C for 2 h produced polyester 1 having M̄_n of 4000 in a 28% yield as well as 4-vinylbenzoic acid in a 9% yield. In the reaction of the sodium salt, both polycondensation and double bond formation occurred. Thus, these polymerizations depended on the counter cations of 2-BEBAs. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2055–2060, 1999     

Free Self-decomposability and Unimodality of the Fuss–Catalan Distributions

Journal of Statistical Physics - We study properties of the Fuss–Catalan distributions $$\mu (p,r)$$, $$p\ge 1$$, $$01$$ there exists $$r_{0}(p)$$, with $$p-1     

Photophysical Properties of Emissive Pyrido[3,2‐c]carbazole Derivatives and Apoptosis Induction: Development towards Theranostic Agents in Response to Light Stimulus

Pyridocarbazole moieties are present in many natural products, such as olivacine and ellipticine, and their derivatives are well‐known anticancer agents. To develop functional therapeutic and diagnostic compounds, three emissive pyrido[3,2‐c]carbazole derivatives, PC‐X , containing secondary or tertiary amine groups, were synthesized from an aminoquinoline derivative using a palladium complex as the catalyst. X‐ray diffraction analyses revealed that PC‐X showed highly planar structures between the pyridine ring and the carbazole framework, exhibiting high fluorescence intensities along with solvatochromic behavior. Imaging of HeLa cells treated with PC‐X showed no specific accumulation into the organelles; however, a comparative examination showed that the accumulation in mitochondria was the highest as compared to nuclei and lysosomes. Cytotoxicity analysis using HeLa cells showed that PC‐H, containing a secondary amine group showed the highest cytotoxicity (IC₅₀≈20 μm ) as compared to another PC‐X having a tertiary amine group. Colocalization with MitoTracker, a typical mitochondrial staining dye, showed apoptosis‐like behavior with remarkable appearance of blebbing during irradiation with near UV light (403 nm), suggesting that the PC‐H may not only behave as a fluorescence probe for the imaging organelles, but also as a therapeutic agent for inducing apoptosis in HeLa cells, thereby functioning as a theranostic agent.     

Analysis of perchlorate in foods and beverages by ion chromatography coupled with tandem mass spectrometry (IC-ESI-MS/MS)

A new IC-ESI-MS/MS method, with simple sample preparation procedure, has been developed for quantification and confirmation of perchlorate (ClO₄⁻) anions in water, fresh and canned food, wine and beer samples at low part-per-trillion (ng l⁻¹) levels. To the best of our knowledge, this is the first time an analytical method is used for determination of perchlorate in wine and beer samples. The IC-ESI-MS/MS instrumentation consisted of an ICS-2500 ion chromatography (IC) system coupled to either an API 2000™ or an API 3200™ mass spectrometer. The IC-ESI-MS/MS system was optimized to monitor two pairs of precursor and fragment ion transitions, i.e., multiple reaction monitoring (MRM). All samples had oxygen-18 isotope labeled perchlorate internal standard (ISTD) added prior to extraction. Chlorine isotope ratio (³⁵Cl/³⁷Cl) was used as a confirmation tool. The transition of ³⁵Cl¹⁶O₄⁻ (m/z 98.9) into ³⁵Cl¹⁶O₃⁻ (m/z 82.9) was monitored for quantifying the main analyte; the transition of ³⁷Cl¹⁶O₄⁻ (m/z 100.9) into ³⁷Cl¹⁶O₃⁻ (m/z 84.9) was monitored for examining a proper isotopic abundance ratio of ³⁵Cl/³⁷Cl; and the transition of ³⁵Cl¹⁸O₄⁻ (m/z 107.0) into ³⁵Cl¹⁸O₃⁻ (m/z 89.0) was monitored for quantifying the internal standard. The minimum detection limit (MDL) for this method in de-ionized water is 5 ng l⁻¹ (ppt) using the API 2000™ mass spectrometer and 0.5 ng l⁻¹ using the API 3200™ mass spectrometer. Over 350 food and beverage samples were analyzed mostly in triplicate. Except for four, all samples were found to contain measurable amounts of perchlorate. The levels found ranged from 5 ng l⁻¹ to 463.5 ± 6.36 μg kg⁻¹ using MRM 98.9 → 82.9 and 100 μl injection.     

The expansion of a chord diagram and the Tutte polynomial

A chord diagram is a set of chords of a circle such that no pair of chords has a common endvertex. A chord diagram $E$ is called nonintersecting if $E$ contains no crossing. For a chord diagram $E$ having a crossing $S=\{x_1{x}_3,x_2{x}_4\}$, the expansion of $E$ with respect to $S$ is to replace $E$ with $E_1=(E?S)\cup \{x_2{x}_3,x_4{x}_1\}$ or $E_2=(E?S)\cup \{x_1{x}_2,x_3{x}_4\}$. For a chord diagram $E$, let $f\left(E\right)$ be the chord expansion number of $E$, which is defined as the cardinality of the multiset of all nonintersecting chord diagrams generated from $E$ with a finite sequence of expansions.In this paper, it is shown that the chord expansion number $f\left(E\right)$ equals the value of the Tutte polynomial at the point $(2,?1)$ for the interlace graph $G_E$ corresponding to $E$. The chord expansion number of a complete multipartite chord diagram is also studied. An extended abstract of the paper was published (Nakamigawa and Sakuma, 2017) [13].     

A search for ? meson nucleus bound state using antiproton annihilation on nucleus

The mass shift of the vector mesons in nuclei is known to be a powerful tool for investigating the mechanism of generating hadron mass from the QCD vacuum. The mechanism is known to be the spontaneous breaking of chiral symmetry. In 2007, KEK-PS E325 experiment reported about 3.4?% mass reduction of the ? meson in medium-heavy nuclei (Cu). This result is possibly one of the indications of the partial restoration of chiral symmetry in nuclei, however, unfortunately it is hard to make strong conclusions from the data. One of the ways to conclude the strength of the ? meson mass shift in nuclei will be by trying to produce only slowly moving ? mesons where the maximum nuclear matter effect can be probed. The observed mass reduction of the ? meson in the nucleus can be translated as the existence of an attractive force between ? meson and nucleus. Thus, one of the extreme conditions that can be achieved in the laboratory is indeed the formation of a ?-nucleus bound state, where the ? meson is ??trapped?? in the nucleus. The purpose of the experiment is to search for a ?-nucleus bound state and measure the binding energy of the system. We will demonstrate that a completely background-free missing-mass spectrum can be obtained efficiently by $(\bar{p}, \phi)$ spectroscopy together with K ^?+??? tagging, using the primary reaction channel $\bar{p} p \rightarrow \phi \phi$ . This paper gives an overview of the physics motivation and the detector concept, and explains the direction of the initial research and development effort.     

Viscosity and lubricity of aqueous NaCl solution confined between mica surfaces studied by shear resonance measurement

We report the viscoelasticity of the thin film of aqueous NaCl solution confined between mica surfaces measured by shear resonance apparatus. The observed shear resonance curves at separations less than ca. 2 nm indicated that the solution exhibits the high lubrication effects under some loads. The effective viscosity (0.1-10 Pa s) obtained for the separations less than 1 nm from a mechanical model was 2-4 orders of magnitude larger than the bulk value. Our study employing a novel shear measurement provided a comprehensive picture for the dynamics of confined water thinner than a few nanometers.     

Enantioselective C-C bond cleavage creating chiral quaternary carbon centers

[Structure: see text] A chiral all-carbon benzylic quaternary carbon center is created by the asymmetric intramolecular addition/ring-opening reaction of a boryl-substituted cyclobutanone, which involves enantioselective beta-carbon elimination from a symmetrical rhodium cyclobutanolate. The asymmetric reaction was successfully applied to a synthesis of sesquiterpene, (-)-alpha-herbertenol.