Casein phosphopeptides–vaterite calcium carbonate enhance cytocompatibility and osteoinductivity of poly(l‐lactic acid)

Although calcium carbonate has been proved to be effective in neutralizing the acid degradation products of poly(l ‐lactic acid) (PLLA), it has no osteoinductivity. In this study, casein phosphopeptides (CPPs)‐containing CaCO₃ vaterite were synthesized by fast precipitation in an aqueous solution of CaCl₂, Na₂CO₃, and 2 mg/ml of CPPs. CaCO₃–PLLA composite membranes (P‐vaterite–CPP) were prepared (CaCO₃/PLLA =1:2) and exhibited uniform structure and increased hydrophilicity. These composite membranes enhanced hydroxyapatite formation after incubated in simulated body fluid at 37°C for 7 days. The P‐vaterite–CPP membranes promoted human bone marrow stromal cells (hBMSCs) proliferation 4 and 7 days after seeding. Scanning electron microscope images of hBMSCs on the composite membranes exhibited a polygonal and unevenly spreading morphology. Immunofluorescent staining of cytoskeleton and focal adhesion showed that hBMSCs had more stress fibers and were more spreading, indicating a good cell adhesion on the CPPs‐containing composite membranes. Osteogenesis related genes (alkaline phosphatase, collagen type, osteocalcin, and osteopontin) expressions were significantly higher on the CPPs‐containing membranes than those on the CPPs‐free membranes (P < 0.05). It can be concluded that the addition of CPPs induces vaterite formation and thus improve cytocompatibility and osteoinductivity of PLLA. POLYM. COMPOS., 36:1213–1223, 2015. © 2014 Society of Plastics Engineers     

Deuterated Curcuminoids: Synthesis,Structures, Computational/Docking and Comparative Cell Viability Assays against Colorectal Cancer

A series of deuterated curcuminoids (CUR) were synthesized, bearing two to six OCD₃ groups, in some cases in combination with methoxy groups, and in others together with fluorine or chlorine atoms. A model ring-deuterated hexamethoxy-CUR–BF₂ and its corresponding CUR compound were also synthesized from a 2,4,6-trimethoxybenzaldehyde-3,5-d₂ precursor. As with their protio analogues, the deuterated compounds were found to remain exclusively in the enolic form. The antiproliferative activities of these compounds were studied by in vitro bioassays against a panel of 60 cancer cell lines, and more specifically in human colorectal cancer (CRC) cells (HCT116, HT29, DLD-1, RKO, SW837, and Caco2) and in normal colon cells (CCD841CoN). The deuterated CUR–BF₂ adducts exhibited better overall growth inhibition by NCI-60 assay, while for other CUR–BF₂ adducts the non-deuterated analogues were more cytotoxic. Results of the more focused comparative cell viability assays followed the same trend, but with some variation depending on cell lines. The CUR–BF₂ adducts exhibited significantly higher cytotoxicity than CURs. Structural studies (X-ray and DFT) and computational molecular docking calculations comparing their inhibitory efficacy with those of known anticancer agents used in chemotherapy are also reported.     

Preparation and applications of novel fluoroalkyl end‐capped sulfonic acid oligomers–silica gel polymer hybrids

Fluoroalkyl end‐capped 2‐methacryloxyethanesulfonic acid homo‐oligomer [R_F–(MES)_n–R_F] and 2‐methacryloxyethanesulfonic acid–N,N‐dimethylacrylamide co‐oligomers [R_F–(MES)_x–(DMAA)_y–R_F] reacted with tetraethoxysilane (TEOS) under acidic conditions to afford R_F–(MES)_n–R_F homo‐oligomer–SiO₂ polymer hybrid and R_F–(MES)_x–(DMAA)_y–R_F co‐oligomer–SiO₂ polymer hybrid, respectively. Thermogravimetric–mass spectra showed that the thermal stability of R_F–(MES)_n–R_F homo‐oligomer–SiO₂ polymer hybrid was superior to that of traditionally well‐known perfluorinated ion exchange polymers such as Nafion 112 (TR). The sol solutions of the fluorinated co‐oligomer–SiO₂ polymer hybrid were applied to the surface modification of glass to exhibit not only a strong oleophobicity imparted by fluorine but also a good hydrophilicity on the glass surface. On the other hand, R_F–(MES)_x–(DMAA)_y–R_F co‐oligomer reacted with TEOS in the presence of a variety of silica nanoparticles (mean diameters: 11–95 nm) under alkaline conditions to afford fluoroalkyl end‐capped oligomers–silica nanoparticles (mean diameters: 32–173 nm) with a good dispersibility and stability in methanol. Similarly, a variety of fluorinated oligomers containing sulfo groups–silica nanoparticles were prepared by the homo‐ and co‐oligomerizations of fluoroalkanoyl peroxides with 2‐methacryloxyethane sulfonic acid (MES) and comonomers such as N,N‐dimethylacrylamide (DMAA) and acryloylmorpholine (ACMO) in the presence of silica nanoparticles. Interestingly, these isolated fluorinated particle powders were found to afford nanometer size‐controlled colloidal particles with a good redispersibility and stability in aqueous and organic media such as methanol. These fluorinated nanoparticles containing sulfo groups were also applied to an excellent heterogeneous catalyst for Bronsted acid‐catalyzed transformations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 110–117, 2007     

Efficient Synthesis of 9‐Tosylaminofluorene Derivatives by Boron Trifluoride Etherate‐Catalyzed Aza‐Friedel–Crafts Reaction of in situ Generated N‐Tosylbenzaldimines

An efficient and expeditious boron trifluoride etherate (BF₃⋅Et₂O) catalyzed one‐pot reaction for the synthesis of N‐tosyl‐9‐aminofluorenes and anthracene derivatives from in situ generated N‐tosylbenzaldimines via an aza‐Friedal–Crafts reaction has been developed. The catalytic reaction shows high substrate tolerance with excellent yields.     

Fabrication and characterization of 3D printable nanocomposite filament based on cellulose nanocrystals and polylactic acid using ionic liquids

Nanocellulose, which is biodegradable and possesses excellent physicochemical properties, has high potential in many applications. However, its intrinsic hydrophilic nature makes it difficult to be used as fillers in most hydrophobic polymer composites. Here, cellulose nanocrystals (CNCs) were successfully prepared using 1-hexly-3-methylimidazolium hydrogen sulfate [Hmim][HSO₄] ionic liquid under optimized conditions at 71°C, ultra-sonication amplitude of 69%, and ultrasonication time of 23 min. The prepared CNCs were surface-modified using 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF₄]. A 3D printable nanocomposite filament containing CNCs embedded in polylactic acid was fabricated via extrusion process at 170°C. The prepared filaments were characterized using universal testing machine, field emission scanning electron microscopy, thermogravimetric analysis, and FTIR. It was shown that CNCs had a diameter and length of 10–24 and 60–400 nm, respectively. It was also found that incorporating 2 wt% of CNCs into the matrix phase increased filaments tensile strength by 2.5% (from 54.59 to 57.35 MPa) due to the plasticization effect of [Bmim][BF₄]. The prepared composites exhibited lower activation energies compared to neat PLA due to the small traces of sulfate group on F-CNC. The mechanical attributes of CNCs/PLA nanocomposites were retained at values comparable to that of fresh PLA and were demonstrated to be 3D printable.     

Antistatic effects and mechanism of ionic liquids for methyl vinyl silicone rubber

The effect of two ionic liquids (ILs), namely, 1‐allyl‐3‐methyl imidazolium chloride ([AMIM]Cl) and 1‐ethyl‐3‐methyl imidazolium tetrafluoroborate ([EMIM]BF₄), on the surface and volume resistivities, mechanical properties, transparency, and water contact angle of methyl vinyl silicone rubber (MVQ) were investigated. The chemical structures of the two ILs before and after heat treatment were characterized by Fourier transform infrared spectroscopy. The morphology and fluorine and chlorine elemental dispersion were characterized by field emission scanning electron microscopy and energy‐dispersive X‐ray spectroscopy mapping, respectively. The antistatic mechanism was revealed. The results show that the MVQ–[EMIM]BF₄ composites had lower surface and volume resistivities than the MVQ–[AMIM]Cl composites. The mechanical properties of the MVQ–[EMIM]BF₄ and MVQ–[AMIM]Cl composites were slightly lower than those of the pristine MVQ. With increasing [EMIM]BF₄ content, the surface and volume resistivities and water contact angle of the MVQ–[EMIM]BF₄ composites decreased. When the content of [EMIM]BF₄ was 2.0 phr, the MVQ–[EMIM]BF₄ composites showed better antistatic performance with lower surface and volume resistivities of 9.6 × 10⁹ Ω and 1.2 × 10¹¹ Ω cm, respectively. The antistatic mechanism of the MVQ–IL composites was ascribed to the synergistic effect of ionic migration and moisture absorption. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45180.     

Study on the relationship between the structure and activities of alkyl methacrylate–maleic anhydride polymers as cold flow improvers in diesel fuels

In order to find efficient cold flow improvers for diesel fuels derived from crude oil, copolymers (R¹MC–MA) were prepared making use of the copolymerization of methacrylate (R¹MC) of various alkyls with maleic anhydride (MA), and terpolymers (R¹MC–MA–R²MC) were prepared by the reaction of long-chain alkyl methacrylate (R¹MC), maleic anhydride (MA), and short alkyl methacrylate (R²MC). The additives were purified and characterized by IR, ¹H–NMR, and GPC. The activities of the synthetic products as the cold flow improvers in two diesel fuels were investigated. The results indicate that: (1) the alkyl chain length of R¹ in R¹MC–MA copolymers significantly affects the solid point depressing performance. When the long-chain alkyl R¹ is n–C₁₄H₂₉– and the reaction material molar ratio (R¹MC/MA) is 1:2, the C₁₄MC–2MA possesses the best ΔSP property; (2) the (C₁₄MC–MA–R²MC) terpolymers all demonstrate excellent solid point depression properties when the short-chain alkyl R² varies from CH₃– to n–C₈H₁₇–; (3) however, all of the tested copolymers and terpolymers do not demonstrate necessary cold filter plugging point depression performance.     

Differential scanning calorimetry studies of the cure of carbon fiber–epoxy composite prepregs

Diaminodiphenyl sulfone (DDS) cured tetraglycidyl-4,4'-diaminodiphenyl methane (TGDDM) epoxies, whose cure reactions are accelerated by BF₃:amine catalysts, are the most common composite matrices utilized in aerospace high performance, fibrous composites. To process reproducible composites requires an understanding of the cure reactions and how these reactions are modified by the BF₃:amine catalysts. In this article we report systematic differential scanning calorimetry (DSC) studies of (i) the constituents of BF₃:NH₂C₂H₅-catalyzed TGDDM–DDS epoxies and their mixtures, (ii) the effect of BF₃:NH₂C₂H₅ concentration on the cure reactions, (iii) the nature of the catalyzed cure reactions, and (iv) the environmental sensitivity of the catalyst. DSC studies are also reported on the cure reaction characteristics and environmental sensitivity of commercial C fiber–TGDDM–DDS epoxy prepregs.     

Low-temperature fabrication of TiO<Subscript>2</Subscript> film on flexible substrate by atmospheric roll-to-roll CVD

Titanium dioxide (TiO₂) thin film was fabricated using titanium isopropoxide as a precursor through an atmospheric low-temperature roll-to-roll chemical vapor deposition method. TiO₂ was deposited on the PET substrate in the temperature range of room temperature to 100°C, and the working pressure was 740 Torr. The surface morphology of TiO₂ thin film was analyzed by field emission scanning electron microscopy and a 2D surface profiler. The results revealed that the growth rate of TiO₂ film was 31 nm/min at 100°C, and it also showed that the surface is uniform and smooth. Moreover, the lowest root mean square roughness (R _q) value of 1.87 nm was obtained for TiO₂ film prepared at 100°C. The composition of TiO₂ film was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The film showed very good chemical and optical properties while increasing the substrate deposition temperature. The UV–Vis spectroscopy analysis revealed that TiO₂ films exhibited excellent optical transmittance, more than 91% observed in the visible region.     

Functional phosphines XII. Heterolytic H2 cleavage and homogeneous CO hydrogenation catalyzed by platinum metal β-aminophosphine complexes

Acetophenone was enantioselectively reduced to 1-phenylethanol (21–71% e.e.) by the use of base-modified Ir and Rh catalysts derived from optically active β-aminophosphines, [{(1R,2S)-, (1R,2R)-, (1S,2S)-Ph₂PCH(Ph)CH(Me)N(H)R}M(COD)]BF₄–KOH (R=H, Me, i-Pr, CH₂Ph), in methanol under H₂ (10 bar). The isolation of an equally active amidoiridium catalyst, [(Ph₂PCH₂CMe₂NH)Ir(COD)], its ability to oxidatively add dihydrogen, and the observation of both H₂/D⁺ and H₂/D₂ exchange reactions during catalysis, which crucially depends on the use of protic solvents, provided evidence for a mechanism involving hydride and proton transfer as well as heterolytic H₂ cleavage on dihydrogen–hydrido–amido and dihydrido–amine tautomers, [{‘P∩NR’}Ir(H₂)H]⁺ and [{‘P∩N(H)R’}IrH₂]⁺, respectively.     

Modification and ionic stimulation of hollow fiber membrane by electric field for water treatment

Hollow fiber membrane (HF) is considered one of the prevalent materials for water treatment; its effectiveness is controlled by permeation and mechanical characteristics. In this study, HF membrane surface was stimulated using electrochemical technique, where binary system of stainless steel cylinder and graphite rod electrodes was used into electrolytic solution of sodium acetate 0.1 M as electrolyte. Two pH of acidic medium (pH = 3.5) and alkaline medium (pH = 8.5) were prepared and different potential between 2 and 10 V were applied. EDX analysis of HF membrane surface revealed the formation of sodium ions on the surface of HF membrane with maximum content of Na⁺ ions 1.84%. Also, HF membrane surface showed variation of roughness (R _a) as, HF membrane surface may undergo distortion by using aggressive conditions of high electric potential (7.5–10 V), The measured raw HF membrane (R _a) was 34.8 nm, while, after electrochemical modification in alkaline medium R _a showed higher values 36, 37, and 41 nm using 2, 2.5, and 5 V, respectively. While, after electrochemical modification in acidic medium (R _a) showed 35, 39, 42, 49, 52 nm for 2, 2.5, 5, 7.5, and 10 V, respectively. Moreover, tensile strength Young's modulus, break stress and break strain were measured after electrochemical modification in both acidic and alkaline mediums and maximum porosity value 76.84% was observed after 30 min in acidic medium.     

Comparative Study of Powders Based on the ZrO<Subscript>2</Subscript>–Y<Subscript>2</Subscript>O<Subscript>3</Subscript>–СeO<Subscript>2</Subscript> System Obtained by Various Liquid Phase Methods of Synthesis

Using the liquid-phase methods of synthesis—the coprecipitation of hydroxides and the hydrothermal method—mesoporous xerogels are obtained based on the ZrО₂–Y₂О₃–CeО₂ system with 5–8-nm particles and powders (after the heat treatment of xerogels at 600°C) with a coherent scattering region (CSR) size of 9 to 10 nm and S_sp = 96–156 m²/g. After calcination at 1400°C, the powders are transformed into tetragonal solid solutions with a CSR size of 65 nm in the synthesis by the coprecipitation method, and they are transformed into solid solutions with a CSR size of 84 nm with a high degree of tetragonality of c/a = 1.438–1.431 in the synthesis by the hydrothermal method.     

Ionic Liquids Promoted the C-Acylation of Acetals in Solvent-free Conditions

The synthesis of a series of fourteen 4-alkoxy-1,1,1-trihalo-3-alken-2-ones (2,3) [CX₃COC(R²)=C(R¹)OMe, where X = Cl, F; R¹/R² = Me/H, Bu/H, i-Bu/H, Ph/H, Thien-2-yl/H, –(CH₂)₄–, –CH(CH₂)₄CH(CH₂)₂–] from the acylation reactions of acetals (1) with trichloroacetyl chloride or trifluoroacetic anhydride in the presence of equimolar amounts of pyridine and imidazolium based ionic liquid ([BMIM][BF₄] or [BMIM][PF₆]) is reported. The reaction time, yields and IL recyclation are also investigated and this method showed advantages over the methods described in the literature.     

First crystal structure determination and high-frequency EPR study of an organoarsanecopper radical complex

The red radical complex {(μ-bptz)[Cu(AsPh₃)₂]₂}(BF₄) 1, bptz=3,6-bis(2-pyridyl)-1,2,4,5-tetrazine, was obtained as a stable species and characterized by X-ray crystallography, spectroelectrochemistry and EPR at 9.5 and 285 GHz. Comparison with the previously reported {(μ-bptz)[Cu(PPh₃)₂]₂}(BF₄) 2 reveals longer Cu-element bonds by about 0.1 Å but otherwise a similar “organic sandwich” structure involving intramolecular π(phenyl)–π(tetrazine)–π(phenyl) interactions, a 3+1 coordination at the copper(I) centers, and averaged tetrazine intraring bond distances. Reversible oxidation to a blue dication with an intense MLCT band at 650 nm occurs at −0.24 V vs. Fc^+/o. EPR studies show the effect of the higher spin–orbit coupling constant of the As vs. P atoms through slightly larger g anisotropy as determined through high frequency measurements.     

Theoretical Estimation of Acid Strength of Fluorine Hydrogen-Boron Fluoride Complexes

Abstract

The calculation of complexes R _n BF_3-n . HF (there is R = CH₃ and C₂H₅) has been carried out by the quantum-chemical semi-empirical MNDO method in Dewar and Teel parameterization. The geometrical and electronic structure of these complexes was obtained. On an example of simple H-acids we estimated their acid strength. We found that irrespective of the ligand surrounding of B atom the complexes R _n BF_3-n HF have rather high acid strength (pK _a = 17.9 14.9).     

Synthesis of Short Peptides with Perfluoroalkyl Side Chains and Evaluation of Their Cellular Uptake Efficiency

With an increasing demand for macromolecular biotherapeutics, the issue of their poor cell-penetrating abilities requires viable and relevant solutions. Herein, we report tripeptides bearing an amino acid with a perfluoroalkyl (R_F) group adjacent to the α-carbon. R_F-containing tripeptides were synthesized and evaluated for their ability to transport a conjugated hydrophilic dye (Alexa Fluor 647) into the cells. R_F-containing tripeptides with the fluorophore showed high cellular uptake efficiency and none of them were cytotoxic. Interestingly, we demonstrated that the absolute configuration of perfluoroalkylated amino acids (R_F-AAs) affects not only nanoparticle formation but also the cell permeability of the tripeptides. These novel R_F-containing tripeptides are potentially useful as short and noncationic cell-penetrating peptides (CPPs).     

A NIR Emitting Cyanine with Large Stokes’ Shift for Mitochondria and Identification of their Membrane Potential Disruption

An NIR emitting (λ_em≈730 nm) cyanine probe ExCy was synthesized in good yields by extending the π-conjugation length (i. e., with furan moiety) to the donor-accepter system. ExCy exhibited a large Stokes’ shift (Δλ≈100 nm) due to strong intramolecular charge transfer (ICT), and high fluorescence quantum yield (Φ_fl≈0.47 in DCM). Due to its low fluorescence in an aqueous environment (Φ_fl≈0.007 in H₂O), the probe exhibited the potential of achieving a large fluorescence turn-on upon entering a hydrophobic cellular environment. Fluorescence confocal microscopy studies revealed that ExCy was readily excitable with a far-red laser line (i. e., 640 nm) while the corresponding emission was collected in the NIR region. ExCy exhibited excellent selectivity towards live cell mitochondria according to the co-localization studies. The probe also exhibited high photostability, long-term imaging ability and wash-free staining ability, when being applied to live cells. Our studies indicated that the mitochondrial localization of ExCy was dependent on the membrane potential of the mitochondria. ExCy was successfully utilized as a mitochondrial membrane potential dysfunction indicator to visually identify cells with mitochondrial dysfunction via fluorescence confocal microscopy. ExCy was further examined for potential in vivo imaging of zebrafish.     

Hydrolytic degradation of biobased poly(butylene succinate‐co‐furandicarboxylate) and poly(butylene adipate‐co‐furandicarboxylate) copolyesters under mild conditions

It is indispensable to investigate hydrolytic degradation behavior to develop novel (bio)degradable polyesters. Biobased and biodegradable copolyesters poly(butylene adipate‐co ‐butylene furandicarboxylate) (PBAF) and poly(butylene succinate‐co ‐butylene furandicarboxylate) (PBSF) with BF molar fraction (?_BF) between 40 and 60% were synthesized in this study. The hydrolytic degradation of film samples was conducted in a pH 7.0 PBS buffer solution at 25 °C. Slight mass loss (1–2%) but significant decrease in intrinsic viscosity (35–44%) was observed after 22 weeks. The apparent hydrolytic degradation rate decreased with increasing ?_BF and initial crystallinity. Meanwhile, PBAFs degraded slightly faster than PBSFs with the same composition. The ?_BF and crystallinity increased slowly with degradation time, suggesting the aliphatic moiety and the amorphous region are more susceptible to hydrolysis. And high enough tensile properties were retained after hydrolysis degradation, indicating PBAF and PBSF copolyesters are hydrolytically degradable, with tunable hydrolytic degradation rate and good balance between hydrolytic degradability and durability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44674.     

Lowering of sintering temperature and microwave dielectric properties of BaTi4O9 ceramics prepared by the polymeric precursor method

Low temperature sintering and microwave dielectric properties of barium polytitanate (BaO–4TiO₂) ceramics prepared by means of polymeric precursor route based on the Pechini process were investigated. Pure and fine BaTi₄O₉ powders with particle sizes of 100–200 nm were derived by thermal decomposition of amorphous gel precursor (above 750 °C). They formed single orthorhombic BaTi₄O₉ phase and showed fine and well-dispersed by XRD and SEM observation. The high sintering ability of the prepared powders enabled the fabrication of dielectric ceramics at low sintering temperatures (1200–1300 °C). The well-sintered BaTi₄O₉ ceramics with high relative densities (95%) were found to show excellent microwave dielectric properties compared to those prepared by conventional method at the same sintering temperature.     

Synthesis of hyperbranched poly(3‐methyl‐3‐hydroxymethyloxetane) and their application to separate basic proteins by adsorption coated column

A series of hyperbranched poly(3‐methyl‐3‐hydroxymethyloxetane)s with different degree of branching were synthesized using BF₃·OEt₂ as initiator and coated on the inner surface of the fused‐silica capillaries. In the pH range of 3–9, the coated capillaries reduced electro‐osmotic flow by about four times lower than the bare fused‐silica capillary. The coated capillaries also displayed good resistance to adsorption of cationic proteins, providing clean separations of a mixture of Lysozyme, Cytochrome c, and Ribonuclease A around pH 3–6 in phosphate buffer. The separation efficiency in terms of peak shape was excellent compared with bare fuse‐silica capillary. The separation efficiency of hyperbranched poly(3‐methyl‐3‐hydroxymethyloxetane) with degree of branching of 0.43‐coated capillary column for Lysozyme reached 10⁶ plates/m with a resolution of 7.1, and the coated capillary column had good migration time reproducibility. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010