Optimization of Solution Condition for an Effective Electrochemical Reduction of N2O

An effective electrochemical reduction of nitrous oxide (N₂O) is established by controlling solution compositions in this study. N₂O was electrochemically reduced varying solvent composition and supporting electrolytes (K₂SO₄ and Na₂SO₄) concentrations. The differences in reduction current density and solution resistance were analyzed via linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS), respectively, depending on solution conditions. UV‐Vis spectroscopy was adopted to measure the solubility of N₂O. As a result, among the conditions investigated in this study, 300 mM of K₂SO₄ and aqueous based solution were revealed as an optimum condition for the electrochemical N₂O reduction. At 300 mM of K₂SO₄, the highest current density was obtained due to a high conductance of the electrolyte and a moderate solubility of N₂O.     

Visualizing Microglia with a Fluorescence Turn‐On Ugt1a7c Substrate

Microglia, the brain‐resident macrophage, are involved in brain development and contribute to the progression of neural disorders. Despite the importance of microglia, imaging of live microglia at a cellular resolution has been limited to transgenic mice. Efforts have therefore been dedicated to developing new methods for microglia detection and imaging. Using a thorough structure–activity relationships study, we developed CDr20, a high‐performance fluorogenic chemical probe that enables the visualization of microglia both in vitro and in vivo. Using a genome‐scale CRISPR‐Cas9 knockout screen, the UDP‐glucuronosyltransferase Ugt1a7c was identified as the target of CDr20. The glucuronidation of CDr20 by Ugt1a7c in microglia produces fluorescence.     

Polymerase Chain Reaction-based Detection of Total and Specific Vibrio Species

The polymerase chain reaction (PCR) technique is widely used for efficient detection of food-borne pathogens because of speed and specificity. However, PCR methods have focused mostly on species-specific detection. In the present work, we describe a PCR-based method for the simultaneous detection of all Vibrio species because lots of them are notorious food-borne human pathogens. We then combined this total detection method with specific detection of Vibrio cholerae pathogen. Using a degenerate primer set based on the sequence of the potassium uptake gene, trkA, we were able to successfully detect all Vibrio species. Specific detection of V. cholerae was also possible using primer sets based on putative flagellin sequence. Importantly, simultaneous total and species-specific Vibrio detection was possible using all two primer sets in a multiplexed PCR strategy. Thus, the PCR method we have developed is applicable to both simultaneous and two-step detection of total and specific Vibrio species.     

Growth of poly(pseudorotaxane) on gold using host-stabilized charge-transfer interaction

A novel supramolecular polymer (poly(pseudorotaxane)) in which the repeating units are linked by host-stabilized charge-transfer interaction between the guest molecules is grown on gold and characterized.     

Experimental and theoretical study on the olefin metathesis of alkenyl Baylis-Hillman adducts using second-generation Grubbs catalyst

[reaction: see text] We have investigated the olefin metathesis from alkenyl Baylis-Hillman adducts using second-generation Grubbs catalyst. In the experiment, the ring-closing metathesis (RCM) product could not be found, while the cross-metathesis (CM) products were found. The computational studies provided consistent explanations for the experimental result. The most limiting factor for the RCM process using second-generation Grubbs catalyst is caused by the high strain and steric effect in the metallacyclobutane intermediates.     

Metallic macrocycle with a 1,3-alternate calix[4]arene phosphorus ligand

The preparation of an 1,3-alternate calix[4]arene phosphorus ligand, 25,27-bis(2-(diphenylphosphino)ethoxy)-26,28-bis(1-propyloxy)calix[4]arene (3), is presented. Ligand 3 is obtained in three steps in 64% overall yield. Reaction of 3 with [Rh(cot)2]BF4 produced the encapsulated rhodium complex [Rh[(P,P)-diphen-calix[4]arene]]BF4 (4). As revealed by a single-crystal X-ray diffraction study, the rhodium center has a bent coordination environment with a P-Rh-P angle of 135.66(3) degrees. Palladation of 3 employing [Pd(MeCN)4](BF4)2 yielded the chelate palladium complex 7 in which the palladium center has a slightly bent configuration. Treatment of the ligand with Pd(cod)Cl2 and [Pd(eta3-C4H7)(THF)2]BF4 leads to the isolation of the monometallic complex. Full characterization includes X-ray structural studies of compounds 3, 4, and 6.     

Imidazolium ion-terminated self-assembled monolayers on Au: effects of counteranions on surface wettability

Self-assembled monolayers presenting imidazolium ions at the tail ends (SAMIMs) having different counteranions have been prepared on Au, and the measurement of water contact angles of the surfaces proved to be an extremely valuable simple technique for quantifying the effects of counteranions on hydrophilicity and hydrophobicity of SAMIMs, which will be extrapolated to the water miscibility of the related ionic liquids.     

SSA-MOA: a novel CTC isolation platform using selective size amplification (SSA) and a multi-obstacle architecture (MOA) filter

Circulating tumor cells (CTCs) have gained increasing attention as physicians and scientists learn more about the role these extraordinarily rare cells play in metastatic cancer. In developing CTC technology, the critical criteria are high recovery rates and high purity. Current isolation methods suffer from an inherent trade-off between these two goals. Moreover, ensuring minimal cell stress and robust reproducibility is also important for the clinical application of CTCs. In this paper, we introduce a novel CTC isolation technology using selective size amplification (SSA) for target cells and a multi-obstacle architecture (MOA) filter to overcome this trade-off, improving both recovery rate and purity. We also demonstrate SSA-MOA's advantages in minimizing cell deformation during filter transit, resulting in more stable and robust CTC isolation. In this technique, polymer microbeads conjugated with anti-epithelial cell adhesion molecules (anti-EpCAM) were used to selectively size-amplify MCF-7 breast cancer cells, definitively differentiating from the white blood cells (WBCs) by avoiding the size overlap that compromises other size selection methods. 3 μm was determined to be the optimal microbead diameter, not only for size discrimination but also in maximizing CTC surface coverage. A multi-obstacle architecture filter was fabricated using silicon-on-glass (SOG) technology-a first such application of this fabrication technique-to create a precise microfilter structure with a high aspect ratio. The filter was designed to minimize cell deformation as simulation results predicted that cells captured via this MOA filter would experience 22% less moving force than with a single-obstacle architecture. This was verified by experiments, as we observed reliable cell capture and reduced cell deformation, with a 92% average recovery rate and 351 peripheral blood leukocytes (PBL) per millilitre (average). We expect the SSA-MOA platform to optimize CTC recovery rates, purity, and stability, increasing the sensitivity and reliability of such tests, thereby potentially expanding the utilization of CTC technologies in the clinic.     

Adsorption and thermal decomposition of 2-octylthieno[3,4-b]thiophene on Au(111)

The adsorption and thermal stability of 2-octylthieno[3,4-b]thiophene (OTTP) on the Au(111) surfaces have been studied using scanning tunneling microscopy (STM), temperature programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). UHV-STM studies revealed that the vapor-deposited OTTP on Au(111) generated disordered adlayers with monolayer thickness even at saturation coverage. XPS and TPD studies indicated that OTTP molecules on Au(111) are stable up to 450K and further heating of the sample resulted in thermal decomposition to produce H(2) and H(2)S via C-S bond scission in the thieno-thiophene rings. Dehydrogenation continues to occur above 600K and the molecules were ultimately transformed to carbon clusters at 900K. Highly resolved air-STM images showed that OTTP adlayers on Au(111) prepared from solution are composed of a well-ordered and low-coverage phase where the molecules lie flat on the surface, which can be assigned as a (9×2√33)R5° structure. Finally, based on analysis of STM, TPD, and XPS results, we propose a thermal decomposition mechanism of OTTP on Au(111) as a function of annealing temperature.