Efficacy and safety of factor Xa inhibitors in low body weight patients.

STUDY OBJECTIVE: The purpose of this study is to provide evidence for the safety and efficacy of factor Xa inhibitors in patients with a weight ≤60 kg or BMI < 18.5 kg/m2 . DESIGN: Multicenter, retrospective, cohort study. SETTING: Twenty-two Ascension Health hospitals. PATIENTS: Low-body-weight adult patients (weight ≤ 60 kg or BMI < 18.5 kg/m2 ) receiving treatment for atrial fibrillation or venous thromboembolism. INTERVENTION: Factor Xa inhibitors (apixaban or rivaroxaban) or warfarin. MEASUREMENTS AND MAIN RESULTS: This study included 2538 patients between the factor Xa inhibitors (n = 1695) and warfarin (n = 843) groups with a mean weight of 53.5 ± 5.5 kg and BMI of 20.7 ± 3.1 kg/m2 . No significant difference in time to major bleeding was noted after controlling for potential confounders (HR 1.03, 95% CI 0.70-1.53, p = 0.87); similar results were seen following propensity score matching. Thromboembolism (5.3% vs. 6.2%, p = 0.38), composite major + clinically relevant nonmajor bleeding (9.8% vs. 11.5%, p = 0.18), and all-cause mortality (10.7% vs. 12.8%, p = 0.12) were similar between patients receiving factor Xa inhibitors versus warfarin. CONCLUSION: No differences in safety or effectiveness were noted between factor Xa inhibitors versus warfarin. These findings provide encouraging evidence to support the use of factor Xa inhibitors in low-body-weight patients.

Improving the Conductivity of Amide-Based Small Molecules through Enhanced Molecular Packing and Their Application as Hole Transport Mediators in Perovskite Solar Cells.

Organic-inorganic hybrid halide perovskite solar cells (PSCs) have attracted substantial attention from the photovoltaic research community, with the power conversion efficiency (PCE) already exceeding 26%. Current state-of-the-art devices rely on Spiro-OMeTAD as the hole-transporting material (HTM); however, Spiro-OMeTAD is costly due to its complicated synthesis and expensive product purification, while its low conductivity ultimately limits the achievable device efficiency. In this work, we build upon our recently introduced family of low-cost amide-based small molecules and introduce a molecule (termed TPABT) that results in high conductivity values (∼10-5 S cm-1 upon addition of standard ionic additives), outperforming our previous amide-based material (EDOT-Amide-TPA, ∼10-6 S cm-1) while only costing an estimated $5/g. We ascribe the increased optoelectronic properties to favorable molecular packing, as shown by single-crystal X-ray diffraction, which results in close spacing between the triphenylamine blocks. This, in turn, results in a short hole-hopping distance between molecules and therefore good mobility and conductivity. In addition, TPABT exhibits a higher bandgap and is as a result more transparent in the visible range of the solar spectrum, leading to lower parasitic absorption losses than Spiro-OMeTAD, and has increased moisture stability. We applied the molecule in perovskite solar cells and obtained good efficiency values in the ∼15% range. Our approach shows that engineering better molecular packing may be the key to developing high-efficiency, low-cost HTMs for perovskite solar cells.

Terahertz Emission via Optical Rectification in a Metal-Free Perovskite Crystal.

We report on the emission of high-intensity pulsed terahertz radiation from the metal-free halide perovskite single crystal methyl-DABCO ammonium iodide (MDNI) under femtosecond illumination. The power and angular dependence of the THz output implicate optical rectification of the 800 nm pump as the mechanism of THz generation. Further characterization finds that, for certain crystal orientations, the angular dependence of THz emission is modulated by phonon resonances attributable to the motion of the methyl-DABCO moiety. At maximum, the THz emission spectrum of MDNI is free from significant phonon resonances, resulting in THz pulses with a temporal width of <900 fs and a peak-to-peak electric field strength of approximately 0.8 kV cm-1-2 orders of magnitude higher than any other reported halide perovskite emitters. Our results point toward metal-free perovskites as a promising new class of THz emitters that brings to bear many of the advantages enjoyed by other halide perovskite materials. In particular, the broad tunability of optoelectronic properties and ease of fabrication of perovskite materials opens up the possibility of further optimizing the THz emission properties within this material class.

Voltage-induced fluorescence lifetime imaging of a BODIPY derivative in giant unilamellar vesicles as potential neuron membrane mimics.

Fluorescence lifetime imaging (FLIM) was used to study the behaviour of a BODIPY dye in a giant unilamellar vesicle (GUV) in the presence of an electric field. The modulation of the electric field resulted in distinctive fluorescence lifetime changes in line with environment alterations within the membrane mimic.

Autocatalytic photodegradation of [Ru(II)(2,2'-bipyridine)2DAD]+ (DADH = 1,2-dihydroxyanthracene-9,10-dione) by hydrogen peroxide under acidic aqueous conditions.

As part of a continuing effort to identify ruthenium agents capable of the photorelease of anthraquinone-based ligands the complexes Δ/Λ-[Ru(bpy)2DAD]+ (bpy = 2,2'-bipyridine) were produced by the reaction of 1,2-dihydroxyanthracene-9,10-dione (DADH) with chirally pure Δ/Λ-[Ru(bpy)2(py)2][(+)-O,O'-dibenzoyl-d-tartrate]·12H2O (py = pyridine). A very subtle difference in the chemical shift of the hydroxyl proton in their high-field 1H NMR spectra was observed, supporting that the OH proton is susceptible to a small change in environment at the metal centre. The excited state lifetime of the complexes, as measured by femtosecond pump-probe spectroscopy, was 7.1 (±0.8) ps in water (pH 2) and 13 (±1) ps in MeCN. Illumination of a sample of Λ-[Ru(bpy)2DAD]+ in water (pH 2) in the presence of hydrogen peroxide resulted in decomposition of the complex. The decay profile, as monitored at several wavelengths, was sigmoidal indicating the reaction was autocatalytic, in which the product formed catalysed decomposition of the starting complex. A mechanism is proposed that relies on participation of the uncoordinated hydroxyl group on the anthraquinone ligand in promoting water loss and radical formation in the excited state. The radical is oxidised by peroxide to generate the ruthenium(iii) complex, which behaves as an oxidant in the autocatalytic process.

Photocatalysed decolouration of indigo in solution via in situ generation of an organic hydroperoxide.

Indigo, an emblematic violet dye used for thousands of years to colour fabric, is resistant to fading on exposure to sunlight. Prior work has indicated that indigo is reactive towards both hydroperoxyl radicals and superoxide anions in solution. In order to promote photobleaching of indigo, we have utilised a BOPHY-based (BOPHY = aryl fused symmetrical pyrrole-BF2 complex) chromophore known to form both superoxide ions and a stable alkyl hydroperoxide under illumination in aerated solution. Selective irradiation of the photocatalyst causes relatively fast fading of indigo, with the rate increasing gently with increasing concentration of indigo. Molecular oxygen and light are essential for effective bleaching. One molecule of photocatalyst can bleach more than 40 molecules of indigo. An active component of the photocatalyst is a butylated hydroxytoluene (BHT) residue which itself quenches the triplet excited state of indigo. This provides an ancillary mechanism for effecting photofading of indigo but, because the triplet is formed in very low yield, this route is less practical.

Enhanced in vivo Optical Imaging of the Inflammatory Response to Acute Liver Injury in C57BL/6 Mice Using a Highly Bright Near-Infrared BODIPY Dye.

Delving deeper is possible in whole-body in vivo imaging using a super-bright membrane-targeting BODIPY dye (BD). The dye was used to monitor homing of ex vivo fluorescently labelled neutrophils to an injured liver of dark-pigmented C57BL/6 mice. In vivo imaging system (IVIS) data conclusively showed an enhanced signal intensity and a higher signal-to-noise ratio in mice receiving neutrophils labelled with the BD dye relative to those labelled with a gold standard dye at 2 h post in vivo administration of fluorescently labelled cells. Fluorescence-activated cell sorting (FACS) confirmed that BD is nontoxic, and an exceptional cell labelling dye that opens up precision deep-organ in vivo imaging of inflammation in mice routinely used for biomedical research. The origin of enhanced performance is identified with the molecular structure and the distinct localisation of the dye within cells that enable remarkable changes in its optical parameters.

Rosindone revisited: a computational and photophysical study of 7-phenylbenzo[a]phenazine-5(7H)-one (PBP).

A reasonable gram quantity of the crystalline red dye 7-phenylbenzo[a]phenazine-5(7H)-one (PBP) was synthesised by the condensation of N-phenylbezene-1,2-diamine with 2-hydroxynaphthalene-1,4-dione in acetic acid (58% yield). The molecular structure of the dye, as determined by single-crystal X-ray crystallography, reveals a near planar phenazinone-like core, and an N-phenyl group twisted out of this plane by around 85°. The CO bond length of 1.241(2) Å is consistent with double bond character, which supports minor ground state zwitterionic character to the compound. The wavelength maximum for the observed partially structured low-energy absorption band is relatively insensitive to changes in the solvent polarity and polarizability. TD-DFT calculations predict that the long wavelength absorption envelope originates from localised π-π* transitions with no contribution from an n-π* state. The fluorescence quantum yield and singlet lifetime of the dye in MeCN are 0.12 and 3.0 ns, respectively. Fluorescence maxima are slightly sensitive to the solvent and changes in the Stokes shifts for a small series of alkanols were fitted to the Lippert-Mataga equation to afford a change in dipole moment of 8 ± 2 D. Calculations also reveal that full rotation of the N-phenyl group is severely restricted in the ground state (ΔEGS = 29 kcal mol-1) and in the first-excited singlet state (ΔEES = 34 kcal mol-1). The rocking back and forth of the phenyl group distorts the phenazinone-like backbone as it becomes co-planar and a minor solvent viscosity effect was observed in hydrogen bonding alkanol solvents.

Nonradiative Decay Channels for a Structurally-Distorted, Monostrapped BODIPY Derivative.

A boron dipyrromethene (BODIPY) derivative has been synthesized whereby a phenoxyl ring attached at the 3-position is bound through the oxygen atom to the boron center. This compound is structurally distorted, with the molecular surface being curved, and undergoes further geometrical perturbation at the excited singlet state level. Fluorescence is readily observed in solution at ambient temperature, with the quantum yield rising with increasing viscosity of the surrounding solvent. Dual-exponential decay kinetics are observed, corresponding to E-type delayed fluorescence. In solution, the emission yield falls with increasing temperature, but the opposite situation is found for the same compound dispersed in an amorphous sugar. These results are considered in terms of two radiationless decay channels. A viscosity-dependent avenue allows the fluorophore to function as a conventional fluorescent rotor for tracking changes in local rheology. A temperature-dependent channel leads to trapping within a new conformation, which is weakly coupled to the ground state but is able to repopulate the emitting state on a relatively slow time scale. Analysis of the experimental data allows estimation of some of the key kinetic parameters as a function of temperature.

Photocatalysis and self-catalyzed photobleaching with covalently-linked chromophore-quencher conjugates built around BOPHY.

Two Chromophore-Quencher Conjugates (CQCs) have been synthesized by covalent attachment of the anti-oxidant dibutylated-hydroxytoluene (BHT) to a pyrrole-BF2 chromophore (BOPHY) in an effort to protect the latter against photofading. In fluid solution, light-induced intramolecular charge transfer is favoured in polar solvents and helps to inhibit photo-bleaching of the chromophore. The rate of photo-fading, which scales with the number of BHT residues, is zero-order in polar solvents but shows a linear dependence on the number of absorbed photons. The zero-order rate constant shows an inverse correlation with the fluorescence quantum yield measured in the same solvent. Photo-bleaching in benzonitrile involves autocatalysis while reaction in cyclohexane shows an unexpected stoichiometry. NMR spectroscopy indicates initial damage takes place at the BHT unit and allows identification of a reactive hydroperoxide as being the primary product. In the presence of an adventitious substrate, this hydroperoxide is a photocatalyst for amide formation under mild conditions.

Locally Excited State-Charge Transfer State Coupled Dyes as Optically Responsive Neuron Firing Probes.

A selection of NIR-optically responsive neuron probes was produced comprising of a donor julolidyl group connected to a BODIPY core and several different styryl and vinylpyridinyl derived acceptor moieties. The strength of the donor-acceptor interaction was systematically modulated by altering the electron withdrawing nature of the aryl unit. The fluorescence quantum yield was observed to decrease as the electron withdrawing effect of the aryl subunit increased in line with changes of the Hammett parameter. The effectiveness of these fluorophores as optically responsive dyes for neuronal imaging was assessed by measuring the toxicity and signal-to-noise ratio (SNR) of each dye. A great improvement of SNR was obtained when compared to the first-generation BODIPY-based voltage sensitive dyes with concomitant toxicity decrease. The mechanism for the optical response is disparate from conventional cyanine-based dyes, opening up a new way to produce effective voltage sensitive dyes that respond well into the NIR region.

One-Pot Synthesis of a Mono-O,B,N-strapped BODIPY Derivative Displaying Bright Fluorescence in the Solid State.

Tin(IV) catalysis allows isolation of a boron dipyrromethene derivative bearing a solitary strap around the boron center. The conditions favor internal cyclization without contamination by side products and provide high yields of product in good purity. A phenolate-based strap imposes chirality and causes geometrical distortion of the dipyrrin. Relatively strong fluorescence is observed for single crystals, evaporated films, and adsorbed layers. Single-crystal absorption and emission spectra resemble those observed from solution with contributions from a dimer.