Nanoliter Quantitative High-Throughput Screening with Large-Scale Tunable Gradients Based on a Microfluidic Droplet Robot under Unilateral Dispersion Mode

Performing quantitative high throughput screening (qHTS) is in urgent need in current chemical, biological, and medical research. In this work, we developed an automated microfluidic dilution and large-scale screening system in the nanoliter range, by combining the droplet-based microfluidic robot technique with a novel unilateral Taylor–Aris dispersion-based dilution approach. The unilateral dispersion approach utilizes multiphase microfluidic design to generate a concentration gradient with fast gradient generation time, low sample/reagent consumption, and high operation efficiency over the widely used bilateral Taylor–Aris dispersion approach adopted in previous dilution systems. The present system is capable of automatically generating a large and tunable range of concentration gradients covering ca. 6 orders of magnitude in droplet arrays and achieving qHTS of a large number of different samples. We applied the microfluidic droplet system in miniaturized enzyme kinetic assay in 8-nL droplets and high-throughput quantitative screening of enzyme inhibitors with a library of 102 compounds. Only 9.8 μL of enzyme solution was consumed in 2448 droplet assays containing 102 compounds and 24 concentrations, representing an approximate 1600-fold reduction compared with multiwell plate-based assays. In the screening, dose–response curves of each tested compound were established and 4 hits (CP-471474, ilomastat, batimastat, and marimastat) were screened to have inhibitory activity to matrix metallopeptidase-9 (MMP-9), which demonstrated that the present system has the potential to provide a miniaturized qHTS platform for drug discovery

Nanoliter Quantitative High-Throughput Screening with Large-Scale Tunable Gradients Based on a Microfluidic Droplet Robot under Unilateral Dispersion Mode

Performing quantitative high throughput screening (qHTS) is in urgent need in current chemical, biological, and medical research. In this work, we developed an automated microfluidic dilution and large-scale screening system in the nanoliter range, by combining the droplet-based microfluidic robot technique with a novel unilateral Taylor–Aris dispersion-based dilution approach. The unilateral dispersion approach utilizes multiphase microfluidic design to generate a concentration gradient with fast gradient generation time, low sample/reagent consumption, and high operation efficiency over the widely used bilateral Taylor–Aris dispersion approach adopted in previous dilution systems. The present system is capable of automatically generating a large and tunable range of concentration gradients covering ca. 6 orders of magnitude in droplet arrays and achieving qHTS of a large number of different samples. We applied the microfluidic droplet system in miniaturized enzyme kinetic assay in 8-nL droplets and high-throughput quantitative screening of enzyme inhibitors with a library of 102 compounds. Only 9.8 μL of enzyme solution was consumed in 2448 droplet assays containing 102 compounds and 24 concentrations, representing an approximate 1600-fold reduction compared with multiwell plate-based assays. In the screening, dose–response curves of each tested compound were established and 4 hits (CP-471474, ilomastat, batimastat, and marimastat) were screened to have inhibitory activity to matrix metallopeptidase-9 (MMP-9), which demonstrated that the present system has the potential to provide a miniaturized qHTS platform for drug discovery

The complete chloroplast genome sequence of <i>Tamarix arceuthoides</i> Bunge and <i>Tamarix ramosissima</i> Ledeb. (Tamaricaceae)

Tamarix L. is of great ecological and economic significance in arid desert ecosystems. This study reports the complete chloroplast (cp) genomic sequences of T. arceuthoides Bunge and T. ramosissima Ledeb., which are currently unknown, by high-throughput sequencing. The cp genomes of T. arceuthoides 1852 and T. ramosissima 1829 were 156,198 and 156,172 bp in length, respectively, and contained a small single-copy region (SSC: 18,247 bp), a large single-copy region (LSC: 84,795 and 84,890 bp, respectively), and a pair of inverted repeat regions (IRs: 26,565 and 26,470 bp, respectively). The two cp genomes possessed 123 genes arranged in the same order, including 79 protein-coding, 36 tRNA, and eight rRNA genes. Of these, 11 protein-coding genes and seven tRNA genes contained at least one intron. The present study found that Tamarix and Myricaria are sister groups with the closest genetic relationship. The obtained knowledge could provide useful information for future phylogenetic, taxonomic, and evolutionary studies on Tamaricaceae.</p

Simultaneous Activation of Peroxydisulfate and Hydrogen Peroxide by Sulfidated Nanoscale Zero-Valent Iron for Efficient MTBE Degradation: Significant Role of Oxygen Vacancy

Nanoscale zero-valent iron (nZVI)-based advanced oxidation processes (AOPs) are limited by the rapidly formed surface layer of iron (oxyhydr) oxides. This restriction can be broken by the simultaneous activation of H2O2 and peroxydisulfate (PDS, S2O82–) over sulfidated nanoscale ZVI (S-nZVI), which displayed a synergistic effect to alleviate the drawbacks of the oxidants used alone. In this work, a biochar-supported S-nZVI (noted as S-nZVI@BC) was employed to simultaneously activate PDS and H2O2 for methyl tert-butyl ether (MTBE) degradation, and the rate constant for S-nZVI@BC/Bi-ox (Bi-ox, bi-oxidant at 1:1 molar ratio of PDS and H2O2) was 3.7-, 4.5-, and 12.8-fold higher than that of nZVI@BC/Bi-ox, S-nZVI@BC/PDS, and S-nZVI@BC/H2O2. According to electron paramagnetic resonance (EPR), X-ray photoelectric spectroscopy (XPS), and in-situ oxygen detection analyses, oxygen vacancies were generated over the shell of S-nZVI@BC during PDS activation, and the oxygen vacancy-contained surface layers promoted H2O2 adsorption and dissociation to produce surface-bound ·OH (·OHads), thus significantly improving H2O2 utilization efficiency and accelerating MTBE degradation. These findings provide promising S-nZVI-based AOPs by combining H2O2 and peroxydisulfate activation for environmental remediation and bring insights for the creation of oxygen vacancy-containing materials for peroxide activation

Macro-Meso-Microporous Metal–Organic Frameworks: Template-Assisted Spray Drying Synthesis and Enhanced Catalysis

Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in many applications. However, most previous studies focus on HP-MOFs with two kinds of pore structures. Herein, a strategy for efficient construction of HP-MOFs possessing macro-meso-micropores using template-assisted spray drying followed by etching process is proposed. Taking ZIF-8 as an example, using polystyrene (PS) templates, the complete HP-ZIF-8 with all the three categories of pores can be easily fabricated. The close arrangement of intrinsic microporous nanosized ZIF-8 (N-ZIF-8) in the spray drying process results in the creation of mesopores, while the macropores are further generated after the removal of PS templates. The structures of macropores and mesopores can be easily adjusted by altering the size and proportion of PS and the size of N-ZIF-8, respectively. Furthermore, this method is extended to the preparation of HP-HKUST-1. As a proof-of-concept, HP-ZIF-8 displays excellent catalytic properties in Knoevenagel reaction owing to its unique pore features. Compared with conventional microsized ZIF-8 (M-ZIF-8) with similar size, HP-ZIF-8 achieves the significantly increased conversion of benzaldehyde from 55% to 100% within 3 h, and shows better recycling performance than N-ZIF-8

Decline in the performance of mice injected with D-ribose in the Morris water maze test.

<p>Conditions for the injection of Rib were the same as those given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024623#pone-0024623-g003" target="_blank">Fig 3</a>. The length of time mice took to find the hidden platform was recorded as latency of escape during each of the seven training days (panel A and B). The length of the searching time spent in the quadrant when the platform was removed during the probe trial is shown in panel C. All values are expressed as means ± S.E.M. * P<0.05, ** P<0.01.</p

Plasmon-Enhanced C–C Bond Cleavage toward Efficient Ethanol Electrooxidation

Ethanol, as a sustainable biomass fuel, is endowed with the merits of theoretically high energy density and environmental friendliness yet suffers from sluggish kinetics and low selectivity toward the desired complete electrooxidation (C1 pathway). Here, the localized surface plasmon resonance (LSPR) effect is explored as a manipulating knob to boost electrocatalytic ethanol oxidation reaction in alkaline media under ambient conditions by appropriate visible light. Under illumination, Au@Pt nanoparticles with plasmonic core and active shell exhibit concurrently higher activity (from 2.30 to 4.05 A mgPt–1 at 0.8 V vs RHE) and C1 selectivity (from 9 to 38% at 0.8 V). In situ attenuated total reflection–surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) provides a molecular level insight into the LSPR promoted C–C bond cleavage and the subsequent CO oxidation. This work not only extends the methodology hyphenating plasmonic electrocatalysis and in situ surface IR spectroscopy but also presents a promising approach for tuning complex reaction pathways

Changes in cell viability in the presence of D-ribose.

<p>The morphology of SH-SY5Y cells was observed by inverted contrast microscopy after incubation with 50 mM Rib (A), or 50 mM Glc (B) for 3 days. Untreated cells were used as controls (C). HEK293T cells treated with the same concentration of Rib (D), Glc (E) and control cells (F) were imaged under the same conditions. SH-SY5Y (G and H) and HEK293T (I and J) cells were incubated with Rib or Glc as indicated and cell viability was measured using the MTT assay at day 2 (G and I), and day 3 (H and J) after addition of the monosaccharides.</p

Unveiling Molecular Transformations of Soil Organic Matter after Remediation by Chemical Oxidation Based on ESI-FT-ICR-MS analysis

Remediation of soils contaminated with organic pollutants is often accomplished by chemical oxidation processes using oxidants such as persulfate or H2O2. However, it is unclear how different oxidants transform soil organic matter (SOM) and affect soil ecosystem services. Herein, two chemical oxidation technologies, Fenton reaction (FT) and base-activation of sodium persulfate (BP), were investigated to remediate diesel-polluted soils. The molecular transformation of SOM was analyzed using excitation–emission matrix fluorescence spectroscopy (EEM FS) and electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). Fulvic acid-like substances and lipids were consumed in both treatments, while the contents of lignin-like and tannin-like substances increased after BP treatment. The oxygen to carbon ratios (O/C), modified aromaticity index (AImod), and double bond equivalent (DBE) of SOM increased significantly in BP-treated soil, while these parameters decreased in FT-treated soil (FTS), suggesting the oxygen-containing, unsaturated and aromatic compounds were produced in BPS but removed in FTS. The increased cation exchange capacity (CEC) value (81.47 cmol/kg) and germination index of wheat seed (97%) for the SOM in BPS indicate the possible favorable effect of persulfate-based treatment on soil quality. Overall, this study advances mechanistic understanding of the effects of H2O2- and persulfate-based soil remediation technologies based on the molecular compositions of SOM and soil quality

Intraperitoneal injection of D-ribose results in an increase in the concentration of glycated serum protein.

<p>Mice were injected (i.p.) with Rib as indicated for 30 days and serum was taken for assays of glycated serum protein. Mice injected with Glc and saline were used as controls. * P <0.05, ** P<0.01.</p