Potassium ion mediated collagen microfibril assembly on mica

Potassium ion can critically effect the interaction between collagen microfibrils and mica leading to different ordered structures that vary dramatically with changing ion concentration. AFM images of the structures formed at different ion concentrations appear to be intermediate stages in the progression from disordered to ordered film. At 200 mM potassium ion concentration, a nanometer-thick array of aligned and bundled microfibrils covering large areas can be created easily and reproducibly on mica.     

Structure-based design of Aurora A & B inhibitors

The Aurora family of serine/threonine kinases are mitotic regulators involved in centrosome duplication, formation of the bipolar mitotic spindle and the alignment of the chromosomes along the spindle. These proteins are frequently overexpressed in tumor cells as compared to normal cells and are therefore potential therapeutic oncology targets. An Aurora A high throughput screen revealed a promising sub-micromolar indazole-benzimidazole lead. Modification of the benzimidazole portion of the lead to a C2 linker with a phenyl ring was proposed to achieve novelty. Docking revealed that a conjugated linker was optimal and the resulting compounds were equipotent with the lead. Further structure-guided optimization of substituents on the 5 & 6 position of the indazole led to single digit nanomolar potency. The homology between the Aurora A & Aurora B kinase domains is 71% but their binding sites only differ at residues 212 & 217 (Aurora A numbering). However interactions with only the latter residue may be used for obtaining selectivity. An analysis of published Aurora A and Aurora B X-ray structures reveals subtle differences in the shape of the binding sites. This was exploited by introduction of appropriately sized substituents in the 4 & 6 position of the indazole leading to Aurora B selective inhibitors. Finally we calculate the conformational energy penalty of the putative bioactive conformation of our inhibitors and show that this property correlates well with the Aurora A binding affinity.     

Submicron particles of SBA-15 modified with MgO as carriers for controlled drug delivery

Submicron particles with modified surface were synthesized by a simple one-pot synthesis approach and used as drug carrier for controlled release. Due to the alkalinity of MgO species on the surface, the amount of a model drug, ibuprofen, adsorbed on the modified surface was increased as compared to pure silica SBA-15 although the surface area was decreased by the surface modification. FTIR investigation indicated that the adsorption state of ibuprofen on MgO modified SBA-15 was different from that on pure silica SBA-15 and pure crystal ibuprofen. The result obtained from in vitro release test exhibited that the surface modification greatly decreased the ibuprofen release rate. In first 6 h in vitro release test, only 63% of the adsorbed ibuprofen was released from the MgO/SBA-15 (Si/Mg=20). In contrast, the release of ibuprofen was complete in 1 h from the pure silica SBA-15 under the same release conditions. The surface modified with MgO created affinity with acidic ibuprofen molecules and retarded the release rate from the mesoporous matrix. In addition, the release rate of ibuprofen could be modulated by varying the content of MgO, and was found to decrease with increasing amount of MgO on surface of SBA-15 submicron particles.     

Synthetic and X-ray structural and reactivity studies of Cp*RuIV complexes containing bidentate dithiocarbonate, xanthate, carbonate, and phosphinate ligands (Cp* = eta5-C5Me5)

The reaction of [Cp*RuCl2]2 (1; Cp* = eta5-C5Me5) with tetraalkyldithiuram disulfides (R2NC(S)SS(S)CNR2, R = Me, Et), isopropylxanthic disulfide ([iPrOC(S)S]2), and bis(thiophosphoryl) disulfide ([(iPrO)2P(S)S]2) led to the isolation of dark-red crystalline solids of Cp*RuIVCl2(eta2-dithiolate) complexes [dithiolate = S2CNR2, DTCR (2a, R = Me; 2b, R = Et), S2COiPr (3), and S2P(iPrO)2 (4)]. Dichlorido substitution in 2 and 3 with DTCEt and S2COiPr anions yielded RuIV derivatives containing bis(DTC) and mixed DTC-dithiocarbonate ligands. These are the first organoruthenium complexes of such ligands. The reaction of monophosphines with 2a resulted in monochlorido substitution, whereas the analogous reaction with 3 resulted in displacement of both chlorido ligands and reduction of the metal center to RuII. Reduction at Ru was also observed in the reaction of 2a with [CpCr(CO)3]2. Of these complexes, only 2 and 3 are air-stable in the solid state for an extended period. All of the complexes have been spectrally characterized, and selected compounds are also crystallographically characterized.     

New luminescent polymers for leds and LECS

Statistical copolymers 5 containing poly(2-dimethyloctylsilyl-1,4-phenylenevinylene) (DMOS-PPV) and poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) have been synthesized using the dehydrohalogenation condensation route. The copolymers show a shift of photoluminescence maxima to longer wavelengths as the proportion of the MEH-PV unit increases. This trend is accompanied by reduced efficiencies and lower turn-on voltages in single layer electroluminescent devices. Light-emitting electrochemical cells (LECs) have been prepared using a blend of DMOS-PPV 1 with poly(ethylene oxide)/lithium triflate and the homopolymer poly[2-methoxy-5-(triethoxymethoxy)-1,4-phenylene vinylene] (MTEM-PPV) 9 with lithium triflate. In comparison with single-layer devices which were fabricated using the homopolymers 1 and poly[2,5-bis(triethoxymethoxy)-1,4-phenylene vinylene] (BTEM-PPV) 10 , the LEC devices showed lower turn-on voltages.     

Nickel(II) meso‐Hydroxyporphyrin Complexes Revisited: Palladium‐Catalysed Synthesis,Electronic Structures of Derived Oxy Radicals,and Oxidative Coupling to a Dioxoporphodimethene Dyad

We report the synthesis and characterisation of new examples of meso‐hydroxynickel(II) porphyrins with 5,15‐diphenyl and 10‐phenyl‐5,15‐diphenyl/diaryl substitution. The OH group was introduced by using carbonate or hydroxide as nucleophile by using palladium/phosphine catalysis. The NiPor?OHs exist in solution in equilibrium with the corresponding oxy radicals NiPor?O^.. The 15‐phenyl group stabilises the radicals, so that the ¹H NMR spectra of {NiPor?OH} are extremely broad due to chemical exchange with the paramagnetic species. The radical concentration for the diphenylporphyrin analogue is only 1 %, and its NMR line‐broadening was able to be studied by variable‐temperature NMR spectroscopy. The EPR signals of NiPor?O^. are consistent with somewhat delocalised porphyrinyloxy radicals, and the spin distributions calculated by using density functional theory match the EPR and NMR spectroscopic observations. Nickel(II) meso‐hydroxy‐10,20‐diphenylporphyrin was oxidatively coupled to a dioxo‐terminated porphodimethene dyad, the strongly red‐shifted electronic spectrum of which was successfully modelled by using time‐dependent DFT calculations.     

Carbon nanotube–ZnO nanocomposite electrodes for supercapacitors

Carbon nanotube (CNT)–zinc oxide (ZnO) nanocomposite and gel poly(vinyl alcohol)–phosphomolybdic acid were employed as the electrode and electrolyte of the experimental supercapacitor cell, respectively. The ZnO nanodots were deposited onto CNT films by ultrasonic spray pyrolysis in different times. The results of electrochemical measurements showed that the electrode with ZnO deposited in 5 min had the optimal capacitive properties among the experimental series, with a lowest interfacial electron transfer resistance, a very high capacitance of 323.9 F/g and good reversibility in the repetitive charge/discharge cycling test.     

Polyamide-imide/polyetherimide dual-layer hollow fiber membranes for pervaporation dehydration of C1–C4 alcohols

To circumvent the common swelling and deteriorated performance of integral asymmetric hollow fiber membranes for pervaporation dehydration, we have developed novel polyamide-imide (PAI)/polyetherimide (PEI) hollow fiber membranes with synergized performance with the aid of dual-layer spinning technology. Dehydration of C1–C4 alcohols has been conducted and the orders of their fluxes and permeances have been analyzed. The hollow fibers spun at 2 cm air gap and annealed at 75 °C exhibit the highest pervaporation performance: separation factors for t-butanol/water and iso-butanol/water binary systems are greater than 50,000 with flux more than 700 g/m² h. A comparison with literature data shows that the newly developed membranes outperform most other polymeric membranes for the dehydration of IPA and butanols. The dual-layer hollow fiber membranes also exhibit good long-term stability up to 200 h. The superior performance can be attributed to (1) the balanced properties of PAI as the selective layer for dehydration pervaporation; (2) the low water uptake and less swelling characteristic of the PEI supporting layer; and (3) the desirable membrane morphology consisting of a fully porous inner layer, a porous interface, and an ultrathin dense-selective outer skin.     

Pressurized hot water extraction of bioactive or marker compounds in botanicals and medicinal plant materials

To reduce the use of organic solvent, pressurized hot water extraction (PHWE) has been shown to be a feasible option for the extraction of bioactive and marker compounds in botanicals and medicinal plants. The parameters that may affect the extraction efficiencies in PHWE include temperature, extraction time and addition of small percentage of organic solvent or surfactants. Currently, applications of PHWE for the extraction of thermally labile compounds in botanicals are still rather limited. PHWE with and without the additional of a small percentage of organic solvent such as ethanol is highly suited for the chemical standardization and quality control of medicinal plants. At the same time, it can be applied at the pilot scale as a manufacturing process for medicinal plants. Surfactant assisted PHWE was found to enhance the extraction of thermally labile and more hydrophobic species in medicinal plants at a lower temperature. The addition of small amount of surfactants in PHWE is highly suited for the determination of bioactive or marker compounds in medicinal plants. With proper optimization, PHWE was observed to have good extraction efficiency and precision when compared to other reference methods of extraction.