Ultrasmall reduced graphene oxide with high near-infrared absorbance for photothermal therapy

We developed nanosized, reduced graphene oxide (nano-rGO) sheets with high near-infrared (NIR) light absorbance and biocompatibility for potential photothermal therapy. The single-layered nano-rGO sheets were ～20 nm in average lateral dimension, functionalized noncovalently by amphiphilic PEGylated polymer chains to render stability in biological solutions and exhibited 6-fold higher NIR absorption than nonreduced, covalently PEGylated nano-GO. Attaching a targeting peptide bearing the Arg-Gly-Asp (RGD) motif to nano-rGO afforded selective cellular uptake in U87MG cancer cells and highly effective photoablation of cells in vitro. In the absence of any NIR irradiation, nano-rGO exhibited little toxicity in vitro at concentrations well above the doses needed for photothermal heating. This work established nano-rGO as a novel photothermal agent due to its small size, high photothermal efficiency, and low cost as compared to other NIR photothermal agents including gold nanomaterials and carbon nanotubes.     

Electrically actuated, pressure-driven liquid chromatography separations in microfabricated devices

Electrolysis-based micropumps integrated with microfluidic channels in micromachined glass substrates are presented. Photolithography combined with wet chemical etching and thermal bonding enabled the fabrication of multi-layer devices containing electrically actuated micropumps interfaced with sample and mobile phase reservoirs. A stationary phase was deposited on the microchannel walls by coating with 10% (w/w) chlorodimethyloctadecylsilane in toluene. Pressure-balanced injection was implemented by controlling the electrolysis time and voltage applied in the two independent micropumps. Current fluctuations in the micropumps due to the stochastic formation of bubbles on the electrode surfaces were determined to be the main cause of variation between separations. On-chip electrochemical pumping enabled the loading of pL samples with no dead volume between injection and separation. A mobile phase composed of 70% acetonitrile and 30% 50 mM acetate buffer (pH 5.45) was used for the chromatographic separation of three fluorescently labeled amino acids in <40 s with an efficiency of >3000 theoretical plates in a 2.5 cm-long channel. Our results demonstrate the potential of electrochemical micropumps integrated with microchannels to perform rapid chromatographic separations in a microfabricated platform. Importantly, these devices represent a significant step toward the development of miniaturized and fully integrated liquid chromatography systems.     

An Improved Procedure for the Purification of Catalytically Active Alkane Hydroxylase from Pseudomonas putida GPo1

Bacterial alkane hydroxylases are of high interest for bioremediation applications as they allow some bacteria to grow in oil-contaminated environments. Furthermore, they have tremendous biotechnological potential as they catalyse the stereo- and regio-specific hydroxylation of chemically inert alkanes, which can then be used in the synthesis of pharmaceuticals and other high-cost chemicals. Despite their potential, progress on the detailed characterization of these systems has so far been slow mainly due to the lack of a robust procedure to purify its membrane protein component, monooxygenase AlkB, in a stable and active form. This study reports a new method for isolating milligramme amounts of recombinant Pseudomonas putida GPo1 AlkB in a folded, catalytically active form to purity levels above 90%. AlkB solubilised and purified in the detergent lauryldimethylamine oxide was demonstrated to be active in catalysing the epoxidation reaction of 1-octene with an estimated K (m) value of 0.2 mM.     

Analysis of peripheral T cells and the CC chemokine receptor (CCR5) delta32 polymorphism in prostate cancer patients treated with carboxymethyl-glucan (CM-G)

β-Glucan, derived from Saccharomyces cerevisiae, is a biological response modifier which affects the innate and adaptive immune responses. The CCR5 chemokine receptor is crucial for immune cell responses. In this study, the effects of the carboxymethylated form of β-glucan (CM-G) on the lymphocyte population of CCR5 genotype patients with prostate cancer (PCa), undergoing androgen deprivation therapy (ADT) was assessed. The CCR5 genotype and lymphocyte population was investigated by cytometry flow in 30 Brazilian patients with advanced PCa who were treated with CM-G for 28 days. The analysis of the CCR5 chemokine receptor revealed that the wild-type genotype Wt/Wt was present in 80% of patients, while the heterozygotic genotype Wt/delta32 was present in 20% of patients. After CM-G administration, a significant increase in CD3(+), CD4(+) and CD8(+) T lymphocytes was observed in patients who displayed the wild-type genotype for the CCR5 chemokine receptor. No association was found between patient's age or length of ADT and increase in T lymphocyte cells. The results demonstrated the ability of CM-G to stimulate CD4(+) and CD8(+) T cells in the peripheral blood of patients carrying a wild-type CCR5 genotype, suggesting an interaction between immunomodulation by CM-G and the CCR5 receptor.     

Adsorption of ammonia on vanadium-antimony mixed oxides

We analyzed the adsorption of ammonia (NH₃) on the VSbO₄(1 1 0) catalyst surface using density functional theory (DFT) calculations. We followed the evolution of the chemical bonds between different atoms of the resulting NH₃/VSbO₄ system and the changes in the electronic structure of the catalyst. NH₃ preferential adsorption geometries were analyzed through the crystal orbital overlap population (COOP) concept and the density of states (DOS) curves. The VSbO₄(1 1 0) surface exhibits Lewis and Brønsted acid sites on which the ammonia molecule can interact. On the Lewis acid site, NH₃ adsorption resulted in the interaction between the N and a surface V-isolated cation. On Brønsted acid site, N interacted with a surface H coming from the chemical dissociation of water. The COOP analysis indicate that NH₃ interaction on the VSbO₄(1 1 0) surface is weak. In addition, the DOS curves show more developed electronic interactions for NH₃ adsorption on Lewis acid site than over Brønsted acid site.     

Charge density matching in templated molybdates

The role of charge density matching in the formation of templated molybdates under mild hydrothermal conditions was investigated through the use of a series of structurally related amines: piperazine, 1,4-dimethylpiperazine, 2,5-dimethylpiperazine and 2,6-dimethylpiperazine. A series of reactions was conducted in which the relative mole fractions of each component were fixed at 2.5 MoO₃:1 amine:330 H₂O:2 H₂SO₄ in order to isolate the effects of the amine, the only variation between reactions was the structure of the amine. Four distinct polyoxomolybdates anions were observed, ranging from zero-dimensional β-[Mo₈O₂₆]⁴⁻ molecular anions to [Mo₃O₁₀]_n²ⁿ⁻ and [Mo₈O₂₆]_n⁴ⁿ⁻ chains and [Mo₅O₁₆]_n²ⁿ⁻ layers. The primary influence over the structure of the molybdate anion is charge density matching with the protonated amine, which was quantified through surface area approximations based upon both calculated molecular surfaces and polyhedral representations of each anion. Secondary influences include amine symmetry and hydrogen-bonding preferences. The synthesis and characterization of two new compounds are reported. Crystal data: [C₆H₁₆N₂][Mo₃O₁₀]·H₂O (1), triclinic, P-1 (no. 2), a=8.0973(7) Å, b=8.8819(9) Å, c=11.5969(11) Å, α=71.362(9)°, β=82.586(8)°, γ=74.213(8)°, Z=2, R/R_w=0.0262/0.0564, and [C₆H₁₆N₂]₂[Mo₈O₂₆] (2), monoclinic, P2₁/n (no. 14), a=7.9987(11) Å, b=12.5324(19) Å, c=16.003(3) Å, β=97.393(14)°, Z=2, R/R_w=0.0189/0.0454.     

Synthesis and characterization of chiral polyamides derived from glycine and (S)-5-amino-4-methoxypentanoic acid

Stereoregular, enantiomerically pure, chiral polyamides of the –AB– type, containing a natural (glycine) and a synthetic [(S)-5-amino-4-methoxypentanoic acid (AMP)] component have been prepared by the active ester polycondensation method. Thus, polyamide 7 was obtained by polycondensation of the conveniently activated H₂NGly–AMPCO₂R unit ( 6 ). In this reaction, 7 appeared accompanied by a considerable amount of cyclic (Gly–AMP)₂ ( 8 ), which makes the isolation and purification of 7 difficult. The formation of cyclic byproducts could be avoided by preparing and polymerizing the oligoamide H₂NGly–AMP–AMPCO₂R ( 11 ), which has the terminal carboxyl group activated as the pentachlorophenyl ester. The resulting polyamide ( 12 ) was obtained in 85% yield and free of macrolactams, such as 8 . The new polyamides 7 and 12 were characterized by elemental analysis and infrared and ¹H- and ¹³C-nuclear magnetic resonance spectroscopies. Thermal studies revealed that 12 is crystalline and yields films with spherulitic texture by slow evaporation of formic acid solutions. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2741–2748, 1998     

Growth of mesoporous materials within colloidal crystal films by spin-coating

A combination of colloidal crystal planarization, stabilization, and novel infiltration techniques is used to build a bimodal porous silica film showing order at both the micron and the nanometer length scale. An infiltration method based on the spin-coating of the mesophase precursor onto a three-dimensional polystyrene colloidal crystal film allows a nanometer control tuning of the filling fraction of the mesoporous phase while preserving the optical quality of the template. These materials combine a high specific surface arising from the nanopores with increased mass transport and photonic crystal properties provided by the order of the macropores. Optical Bragg diffraction from these type of hierarchically ordered oxides is observed, allowing performing of optical monitoring of the different processes involved in the formation of the bimodal silica structure.     

Background vapor from six ionic liquids and the partition coefficients and limits of detection for 10 different analytes in those ionic liquids measured using headspace gas chromatography

The concentration and identity of the compounds detected in the vapor above six ionic liquids by headspace gas chromatography (HS-GC) at 100 degrees C are reported. In addition, the partition coefficients for 10 different compounds in these ionic liquids and limits of detection were measured. These results provide quantitative guidance for the application of ionic liquids for HS-GC.     

Synthetic approaches for noncentrosymmetric molybdates

The use of second-order Jahn-Teller active Mo (VI) centers and chiral organic amines is discussed as an approach to crystallographic noncentrosymmetry. Several series of reactions, conducted under mild hydrothermal conditions, were designed to probe important reaction variables. Correlations between reagent and solvent concentrations and the molybdate structure were investigated using composition space analysis, which allows for the isolation of specific reaction variables. The effects of amine structure variation were probed using multiple series of related amines, which consisted of either linear diamines or ethylenediamine derivatives. The addition of fluoride results in the loss of amine-based structural variations. Chiral organic amines were used to demonstrate the viability of using such components to control the three-dimensional symmetry in new materials. The synthesis, structure, and characterization of eight new organically templated polyoxomolybdates and polyoxofluoromolybdates are reported.