Chlorophyll-Inspired Red-Region Fluorophores: Building Block Synthesis and Studies in Aqueous Media.

Fluorophores that absorb and emit in the red spectral region (600-700 nm) are of great interest in photochemistry and photomedicine. Eight new target chlorins (and 19 new chlorins altogether)-analogues of chlorophyll-of different polarities have been designed and synthesized for various applications; seven of the chlorins are equipped with a bioconjugatable tether. Hydrophobic or amphiphilic chlorins in a non-polar organic solvent (toluene), polar organic solvent (DMF), and aqueous or aqueous micellar media show a sharp emission band in the red region and modest fluorescence quantum yield (Φf = 0.2-0.3). A Poisson analysis implies most micelles are empty and few contain >1 chlorin. Water-soluble chlorins each bearing three PEG (oligoethyleneglycol) groups exhibit narrow emission bands (full-width-at-half maximum <25 nm). The lifetime of the lowest singlet excited state and the corresponding yields and rate constants for depopulation pathways (fluorescence, intersystem crossing, internal conversion) are generally little affected by the PEG groups or dissolution in aqueous or organic media. A set of chlorin-avidin conjugates revealed a 2-fold increase in Φf with increased average chlorin/avidin ratio (2.3-12). In summary, the chlorins of various polarities described herein are well suited as red-emitting fluorophores for applications in aqueous or organic media.

Nanoglassified, optically-active monolayer films of gold nanoparticles for in situ orthogonal detection by localized surface plasmon resonance and surface-assisted laser desorption/ionization-MS.

Localized surface plasmon resonance (LSPR) represents a sensitive and versatile method for detection of biomolecules in a label-free fashion, but identification of bound analytes can be challenging with LSPR alone, especially for samples in a complex medium. We report the fabrication of an optically active, plasmonic film of gold nanoparticles by using a self-assembly and calcination process, which offers orthogonal measurements enabling multifaceted characterization on the same surface with LSPR and surface-assisted laser desorption/ionization mass spectrometry. This proof-of-concept study involves plasmonic characterization of the fabricated nanofilm, real-time monitoring of vesicle-surface interactions toward formation of fluid lipid bilayer, and mass spectrometric analysis of peptides and cytochrome c digest. This multifunction-enabling surface material can yield complementary analytical information, providing new tools for comprehensive analysis of biomolecular samples.

Dual-mode optical sensing of organic vapors and proteins with polydiacetylene (PDA)-embedded electrospun nanofibers.

Optical sensors capable of colorimetric visualization and/or fluorescence detection have shown tremendous potential for field technicians and emergency responders, owing to the portability and low cost of such devices. Polydiacetylene (PDA)-enhanced nanofibers are particularly promising due to high surface area, facile functionalization, simple construction, and the versatility to empower either colorimetric or fluorescence signaling. We demonstrate here a dual-mode optical sensing with electrospun nanofibers embedded with various PDAs. The solvent-dependent fluorescent transition of nanofibers generated a pattern that successfully distinguished four common organic solvents. The colorimetric and fluorescent sensing of biotin-avidin interactions by embedding biotinylated-PCDA monomers into silica-reinforced nanofiber mats were realized for detection of biomolecules. Finally, a PDA-based nanofiber sensor array consisting of three monomers has been fabricated for the determination and identification of organic amine vapors using colorimetry and principal component analysis (PCA). The combination of PCA and the strategy of probing analytes in two different concentration ranges (ppm and ppth) led to successful analysis of all eight amines.

Synthesis of 24 bacteriochlorin isotopologues, each containing a symmetrical pair of 13C or 15N atoms in the inner core of the macrocycle.

Synthetic bacteriochlorins containing site-specific isotopic substitution enable spectroscopic interrogation to delineate physicochemical features relevant to bacteriochlorophylls in photosynthesis but have been little explored. A de novo synthesis has been employed to prepare bacteriochlorins wherein each macrocycle contains a pair of (13)C or (15)N atoms yet lacks substituents other than a geminal dimethyl group in each pyrroline ring. Preparation of a dihydrodipyrrin­acetal with single-isotopic substitution gives rise to a bacteriochlorin that contains two isotopic substitutions symmetrically disposed by a 180° rotation about the normal to the plane of the macrocycle. Eight such isotopically substituted bacteriochlorins were prepared from commercially available reactants (bacteriochlorin sites): ((13)C)paraformaldehyde (1, 11); ((13)C)formamide (4, 14); triethyl ((13)C)orthoformate (5, 15); K(13)CN (6, 16); (13)CH3NO2 (9, 19); N,N-dimethyl((13)C)formamide (10, 20); ((15)N)pyrrole (21, 23); CH3(15)NO2 (22, 24). Some loss of (15)N upon TiCl3-mediated McMurry-type ring closure of a nitro((15)N)hexanone is attributed to a parallel sequence of three reactions (Nef, exchange with natural-abundance NH4OAc buffer, and Paal­Knorr ring closure) leading to the dihydrodipyrrin­acetal. Zinc and copper chelates of each bacteriochlorin also were prepared. Together, the 24 bacteriochlorin isotopologues should provide valuable benchmarks for understanding ground- and excited-state molecular physics of the macrocycles related to photosynthetic function of bacteriochlorophylls.

Unichromophoric platinum-acetylides that contain pentiptycene scaffolds: torsion-induced dual emission and steric shielding of dynamic quenching.

The effect of the rigid bulky pentiptycene scaffolds on the photoluminescence, redox properties, and oxygen sensing behavior of unichromophoric Pt-acetylides is reported. When the pentiptycene groups are near the Pt(PBu3)2 center, the Pt-acetylides display both blue fluorescence and green phosphorescence with long phosphorescence lifetimes (90-202 µs) in THF. Their phosphorescence intensity is highly sensitive to molecular oxygen, and the emission color depends on the concentration of not only oxygen but also the complexes, which allows a feasible determination of oxygen in the range of 1-5% air volume. The dynamic quenching rate constants decrease linearly with increasing the number of pentiptycene groups, revealing the steric shielding effect of the peripheral rings of pentiptycene. A dependence of oxidation potential on the number of pentiptycene groups also revealed the steric shielding effect on the electron transfer between the complexes and the electrode. In a PMMA matrix, the dual emissive properties are diminished due to increased phosphorescence and decreased fluorescence intensity, and the phosphorescence lifetimes are significantly increased (up to ∼700 µs), leading to an "on-off" optical response to oxygen concentration. Both the dual emissive properties and long-lived triplet excitons are attributed to diminished spin-orbit couplings caused by twisting and steric shielding of the π-conjugated backbone around the Pt center.

A low-power bio-potential acquisition system with flexible PDMS dry electrodes for portable ubiquitous healthcare applications.

This work describes a bio-potential acquisition system for portable ubiquitous healthcare applications using flexible polydimethylsiloxane dry electrodes (FPDEs) and a low-power recording circuit. This novel FPDE used Au as the skin contact layer, which was made using a CO2 laser and replica method technology. The FPDE was revised from a commercial bio-potential electrode with a conductive snap using dry electrodes rather than wet electrodes that proposed reliable and robust attachment for the purpose of measurement, and attaching velcro made it wearable on the forearm for bio-potential applications. Furthermore, this study proposes a recording device to store bio-potential signal data and provides portability and low-power consumption for the proposed acquisition system. To acquire differential bio-potentials, such as electrocardiogram (ECG) signals, the proposed recording device includes a low-power front-end acquisition chip fabricated using a complementary metal-oxide-semiconductor (CMOS) process, a commercial microcontroller (MSP430F149), and a secure digital (SD) card for portable healthcare applications. The proposed system can obtain ECG signals efficiently and are comfortable to the skin. The power consumption of the system is about 85 mW for continuous working over a 3 day period with two AA batteries. It can also be used as a compact Holter ECG system.

RNF128 regulates neutrophil infiltration and myeloperoxidase functions to prevent acute lung injury.

Acute lung injury (ALI) is characterised by severe pulmonary inflammation, alveolar-capillary barrier disruption, and pulmonary oedema. Therefore, establishing effective therapeutic targets for ALI prevention is crucial. The present study reports a novel function of RNF128 in regulating LPS-induced ALI. Severe lung damage and increased immune cell infiltration were detected in RNF128-deficient mice. In vitro experiments revealed that RNF128 inhibits neutrophil activation by binding to myeloperoxidase (MPO) and reducing its levels and activity. Moreover, RNF128 regulates alveolar macrophage activation and neutrophil infiltration by interacting with TLR4, targeting it for degradation, and inhibiting NF-κB activation, hence decreasing pro-inflammatory cytokines. Our results demonstrate for the first time that RNF128 is a negative regulator of MPO and TLR4 in neutrophils and alveolar macrophages, respectively. However, AAV9-mediated RNF128 overexpression alleviated lung tissue damage and reduced inflammatory cell infiltration. Thus, RNF128 is a promising therapeutic candidate for pharmacological interventions in ALI.

Highly sensitive detection of proteins based on metal-enhanced fluorescence with novel silver nanostructures.

We present a highly sensitive metal enhanced fluorescence (MEF) method based on a novel silver nanostructure fabricated with Cy5-functionalized silver nanoparticles (AgNPs) and AgNO(3). The analytical performance has been demonstrated by microarray detection of streptavidin (SA) and human IgE. The fluorescence intensity can be enhanced substantially with the combined use of AgNPs and fluorescence enhanced solution (FES). Aptamers have been used for the preparation of Tag-C, which demonstrate IgE detection from 0.5 ng/mL to 16 ng/mL, and the limit of detection is determined to be 0.25 ng/mL. SEM images show nanogaps exist in the aggregated silver nanoparticles and the nanogaps allow for the trap of fluorophores in the nanostructures that emit brighter light upon excitation. The silver nanostructures formed by Tags and FES proved to be an excellent platform for MEF of fluorophores whose excitation and emission occurred between 436 nm and 1000 nm. Finite-difference time-domain (FDTD) simulation has been carried out to confirm the enhanced electromagnetic field inside silver nanostructures, leading to strong overlap/resonance coupling and eventual fluorescence enhancement.

Synthesis and physicochemical properties of metallobacteriochlorins.

Access to metallobacteriochlorins is essential for investigation of a wide variety of fundamental photochemical processes, yet relatively few synthetic metallobacteriochlorins have been prepared. Members of a set of synthetic bacteriochlorins bearing 0-4 carbonyl groups (1, 2, or 4 carboethoxy substituents, or an annulated imide moiety) were examined under two conditions: (i) standard conditions for zincation of porphyrins [Zn(OAc)(2)·2H(2)O in N,N-dimethylformamide (DMF) at 60-80 °C], and (ii) treatment in tetrahydrofuran (THF) with a strong base [e.g., NaH or lithium diisopropylamide (LDA)] followed by a metal reagent MX(n). Zincation of bacteriochlorins that bear 2-4 carbonyl groups proceeded under the former method whereas those with 0-2 carbonyl groups proceeded with NaH or LDA/THF followed by Zn(OTf)(2). The scope of metalation (via NaH or LDA in THF) is as follows: (a) for bacteriochlorins that bear two electron-releasing aryl groups, M = Cu, Zn, Pd, and InCl (but not Mg, Al, Ni, Sn, or Au); (b) for bacteriochlorins that bear two carboethoxy groups, M = Ni, Cu, Zn, Pd, Cd, InCl, and Sn (but not Mg, Al, or Au); and (c) a bacteriochlorin with four carboethoxy groups was metalated with Mg (other metals were not examined). Altogether, 15 metallobacteriochlorins were isolated and characterized. Single-crystal X-ray analysis of 8,8,18,18-tetramethylbacteriochlorin reveals the core geometry provided by the four nitrogen atoms is rectangular; the difference in length of the two sides is ∼0.08 Å. Electronic characteristics of (metal-free) bacteriochlorins were probed through electrochemical measurements along with density functional theory calculation of the energies of the frontier molecular orbitals. The photophysical properties (fluorescence yields, triplet yields, singlet and triplet excited-state lifetimes) of the zinc bacteriochlorins are generally similar to those of the metal-free analogues, and to those of the native chromophores bacteriochlorophyll a and bacteriopheophytin a. The availability of diverse metallobacteriochlorins should prove useful in a variety of fundamental photochemical studies and applications.

A dodecapeptide (YQVTQSKVMSHR) exhibits antibacterial effect and induces cell aggregation in Escherichia coli.

Antimicrobial peptides play an important role in the innate immune response and host defense mechanism. In the present study, we employed phage display technique to screen for inhibitors which may block the phosphoenolpyruvatedependent phosphotransferase system (PTS) pathway and hence retard cell growth. The recombinant histidine-containing phosphocarrier HPr protein was prepared as the target to screen for the tight binders from the phage-displayed random peptide library Ph.D.-12. The biopanning processes were performed and the binding capabilities of the selected phage were further estimated by enzyme-linked immunosorbent assay (ELISA). The single-stranded DNAs of the 20 selected phages were isolated, sequenced, and five corresponding peptides were synthesized. Only one of the five peptides, AP1 (YQVTQSK VMSHR) was found to inhibit the growth of Escherichia coli cells efficiently (IC50~50 µM). Molecular modeling reveals that AP1 may block the EI-HPr interaction and phosphotransfer. Interestingly, AP1 was also found to induce cell aggregation in a concentration-dependent manner. Since glycogen accumulation has been attributed to biofilm formation, the effects of AP1 on the intracellular glycogen levels were measured. The results strongly indicate that the cell aggregation may be caused by the binding of peptide AP1 with HPr to block the interaction of dephosphorylated HPr with glycogen phosphorylase (GP). Because glycogen phosphorylase activity can be activated by HPr-GP interaction, the binding of AP1 to HPr would cause a decreasing rate of glycogen breakdown in M9 medium and accumulation of glycogen, which may lead to eventual cell aggregation. To the best of our knowledge, this is the first study to demonstrate that an inhibitor bound to a dephosphorylated HPr can decouple its regulatory function and induce cell aggregation.

Surface modifications of eight-electron palladium silver superatomic alloys.

Atomically precise thiolate-protected coinage metal nanoclusters and their alloys are far more numerous than their selenium congeners, the synthesis of which remains extremely challenging. Herein, we report the synthesis of a series of atomically defined dithiophosph(in)ate protected eight-electron superatomic palladium silver nanoalloys [PdAg20{S2PR2}12], 2a-c (where R = OiPr, a; OiBu, b; Ph, c) via ligand exchange and/or co-reduction methods. The ligand exchange reaction on [PdAg20{S2P(OnPr)2}12], 1, with [NH4{Se2PR2}12] (where R = OiPr, or OnPr) leads to the formation of [PdAg20{Se2P(OiPr)2}12] (3) and [PdAg20{Se2P(OnPr)2}12] (4), respectively. Solid state structures of 2a, 2b, 3 and 4 unravel different PdAg20 metal frameworks from their parent cluster, originating from the different distributions of the eight-capping silver(I) atoms around a Pd@Ag12 centered icosahedron with C2, D3, Th and Th symmetries, respectively. Surprisingly ambient temperature crystallization of the reaction product 3 obtained by the ligand exchange reaction on 1 has resulted in the co-crystallization of two isomers in the unit cell with overall T (3a) and C3 (3b) symmetries, respectively. To our knowledge, this is the first ever characterized isomeric pair among the selenolate-protected NCs. Density functional theory (DFT) studies further rationalize the preferred geometrical isomerism of the PdAg20 core.

Electron work function: an indicative parameter towards a novel material design methodology.

Electron work function (EWF) has demonstrated its great promise in materials analysis and design, particularly for single-phase materials, e.g., solute selection for optimal solid-solution strengthening. Such promise is attributed to the correlation of EWF with the atomic bonding and stability, which largely determines material properties. However, engineering materials generally consist of multiple phases. Whether or not the overall EWF of a complex multi-phase material can reflect its properties is unclear. Through investigation on the relationships among EWF, microstructure, mechanical and electrochemical properties of low-carbon steel samples with two-level microstructural inhomogeneity, we demonstrate that the overall EWF does carry the information on integrated electron behavior and overall properties of multiphase alloys. This study makes it achievable to develop "electronic metallurgy"-an electronic based novel alternative methodology for materials design.

Increase of signal-to-noise ratio of a collinear holographic storage system with reference modulated by a ring lens array.

We propose an approach of a reference modulation in a collinear holographic storage system to increase the signal-to-noise ratio (SNR). We derive a solution that shows that the point-spread function is related to the autocorrelation function of the reference pattern times a defocusing phase term. Accordingly, the lens-array phase modulation is proposed and demonstrated theoretically. The SNR of the system can be dramatically enhanced to 63.2, rather than 2.3 in the traditional approach.

L-Arginine reduces thioflavin T fluorescence but not fibrillation of bovine serum albumin.

This work examines the effects of L-arginine (L-Arg) on the aggregation and amyloid fibrillation of bovine serum albumin (BSA). We demonstrate that L-Arg dose-dependently reduces thioflavin T (ThT) fluorescence of BSA within the L-Arg concentration range used (0-1.4 M). However, as revealed by electron microscopy, size exclusion chromatography, and dynamic light scattering results, L-Arg does not prevent amyloid-like fibril formation by BSA. We conclude that L-Arg competes against ThT for binding sites on BSA amyloid-like fibrils, leading to biased results in ThT fluorescence measurements. Moreover, the use of ThT fluorescence assay to screen for potential inhibitors against amyloid fibrillation can give misleading results.

Forecasting Air Quality in Taiwan by Using Machine Learning.

This study proposes a gradient-boosting-based machine learning approach for predicting the PM2.5 concentration in Taiwan. The proposed mechanism is evaluated on a large-scale database built by the Environmental Protection Administration, and Central Weather Bureau, Taiwan, which includes data from 77 air monitoring stations and 580 weather stations performing hourly measurements over 1 year. By learning from past records of PM2.5 and neighboring weather stations' climatic information, the forecasting model works well for 24-h prediction at most air stations. This study also investigates the geographical and meteorological divergence for the forecasting results of seven regional monitoring areas. We also compare the prediction performance between Taiwan, Taipei, and London; analyze the impact of industrial pollution; and propose an enhanced version of the prediction model to improve the prediction accuracy. The results indicate that Taipei and London have similar prediction results because these two cities have similar topography (basin) and are financial centers without domestic pollution sources. The results also suggest that after considering industrial impacts by incorporating additional features from the Taichung and Thong-Siau power plants, the proposed method achieves significant improvement in the coefficient of determination (R2) from 0.58 to 0.71. Moreover, for Taichung City the root-mean-square error decreases from 8.56 for the conventional approach to 7.06 for the proposed method.

The effect of cell sedimentation on measuring chondrocyte population migration using a Boyden chamber.

The Boyden chamber assay provides a convenient method of assessing cell migration and measuring cell motility coefficients at the population level. Previous models of this assay completely ignore cell sedimentation in the suspension, assuming that all cells have already settled on the filter surface before commencing migration within the filter. However, ignoring cell sedimentation could lead to poor data interpretation because the time required for cells to settle through the suspension is close to the incubation period of only a few hours. This study models the Boyden chamber assay by incorporating the cell settling process to account for the cells remaining in the upper well when other cells migrate in the filter. The simulations in this study elucidate the experiments in the literature that test the haptotactic and chemotactic responses of rabbit chondrocytes to type II collagen. This study determines the cell population random motility, as well as the haptotaxis and chemotaxis coefficients, by fitting the experimental data. Results show that the chemotactic motility coefficient is 100 times greater than the haptotactic coefficient, and the equilibrium collagen-receptor dissociation constant is about 10-fold the haptotactic counterpart. Diffusion causes the soluble collagen gradients in the chemotactic case to decline over time, while the coated collagen gradients in the haptotactic assay are likely to remain fixed. As a result, the chemotactic case exhibits a lower number of migrated cells than the haptotactic assay. This study also demonstrates the influences of the dimensionless parameters that control cell behavior in the Boyden assay, providing a reference for future experiment designs.

Water-chloride and water-bromide hydrogen-bonded networks: influence of the nature of the halide ions on the stability of the supramolecular assemblies.

Two compounds, namely, [TTPH(2)](Cl)(2) x 4 H(2)O (1) and [TTPH(2)](Br)(2) x 4 H(2)O (2), (TTP = 4'-p-tolyl-2,2':6',2''-terpyridine) were synthesized from purely aqueous media and characterized by physical techniques. In the solid-state structures of these compounds, interesting supramolecular assemblies are observed. In 1, an unusual staircase-like architecture of the tape of edge-shared planar water hexamer is of importance, where the chloride ions are at the two edges of the tape. In 2, the polymeric nature of the water-bromide assembly is of interest, where discrete open-cube water octamers are doubly bridged by bromide ions. Semiempirical and DFT calculations confirm that the nature of the anion indeed affects the topology of the water-halide assemblies. We conclude that the protonated [TTPH(2)](2+) species can act as appropriate receptors for halide ions, which in turn act as a matrix for the formation of polymeric 1D water-halide assemblies.

Miniplate hooking method for repair of type III flexor digitorum profundus avulsion injury with a small bone fragment: case report.

It is difficult to repair a flexor digitorum profundus tendon avulsion injury when the avulsed bone fragment is too small to hold a fixation device. We present a method to address this problem, using a 1-hole hooked device to hold and fix the avulsed bone fragment and flexor digitorum profundus tendon. This is a simple procedure with fewer complications than traditional techniques.

RTN and Annealing Related to Stress and Temperature in FIND RRAM Array.

In this work, an observation on random telegraph noise (RTN) signal in the read current of a FinFET dielectric RRAM (FIND RRAM) device is presented. The RTN signal of a FIND RRAM cell is found to change after the device being subjected to cycling stress. After undergoing cycling stress, RRAM cells have a stronger tendency to show more frequent and intense RTN signals. The increase of noise levels in FIND RRAM cells can be alleviated generally by high temperature anneal, and with this concept, an on chip annealing scheme is proposed and demonstrated.

Spherical Composite Powder by Coupling Polymethyl Methacrylate and Boron Nitride via Spray Drying for Cosmetic Application.

In the present study, spherical composite powder was successfully prepared via spray drying process using polymethyl methacrylate (PMMA) and hexagonal boron nitride (h-BN) powders. The pristine and as-prepared composite powders were examined using scanning electron microscopy, a particle size analyzer, oil absorption, and specific surface area analyses. These powders were then mixed with linseed oil to prepare samples for UV-Visible-Near Infrared spectroscopy investigation to determine their light absorption ability. Blank and powder-added blemish balm creams were examined using a sun protection factor tester and a thermal conductivity tester. In addition, transmittances of these creams were also evaluated. The experimental results show that spray-dried spherical composite powder exhibited good oil absorption ability. The blemish balm cream with 10 wt.% spray-dried composite powder not only exhibited superior sunscreen protection ability, but also good thermal conductivity.