AgNOx as Nitrogen Source for [1+1+3] Cycloaddition of Isocyanides with Isocyanates: Selective Synthesis of 1,2,4-Triazoles.

A novel [1+1+3] annulation of AgNOx, isocyanides, and isocyanates for the selective synthesis of 1,2,4-triazoles is presented herein. In this transformation, AgNOx and isocyanates are used as nitrogen sources instead of the traditional hydrazine or diazonium reagents. This process also involves N-O/C-H/C═N bond cleavage and the construction of new N-N/C-N bonds with a good substrate scope and functional group tolerance.

A novel microfluidic chip integrated with Pt micro-thermometer for temperature measurement at the single-cell level.

Noninvasive and sensitive thermometry of a single cell during the normal physiological process is crucial for analyzing fundamental cellular metabolism and applications to cancer treatment. However, current thermometers generally sense the average temperature variation for many cells, thereby failing to obtain real-time and continuous data of an individual cell. In this study, we employed platinum (Pt) electrodes to construct an integrated microfluidic chip as a single-cell thermometer. The single-cell isolation unit in the microchip consisted of a main channel, which was connected to the inlet and outlet of a single-cell capture funnel. A single cell can be trapped in the funnel and the remaining cells can bypass and flow along the main channel to the outlet. The best capture ratio of a single MCF7 cell at a single-cell isolation unit was 90 % under optimal condition. The thermometer in the micro-chip had a temperature resolution of 0.007 °C and showed a good linear relationship in the range of 20-40 °C (R2 = 0.9999). Slight temperature increment of different single tumor cell (MCF7 cell, H1975 cell, and HepG2 cell) cultured on the chip was continuously recorded under normal physiological condition. In addition, the temperature variation of single MCF7 cell in-situ after exposure to a stimulus (4 % paraformaldehyde treatment) was also monitored, showing an amplitude of temperature fluctuations gradually decreased over time. Taken together, this integrated microchip is a practical tool for detecting the change in the temperature of a single cell in real-time, thereby offering valuable information for the drug screening, diagnosis, and treatment of cancer.

A microfluidic chip platform based on Pt nanozyme and magnetized phage composite probes for dual-mode detecting and imaging pathogenic bacteria viability.

The detection of pathogen viability is critically important to evaluate its infectivity. In the study, an integrated microfluidic chip based on dual-mode analytical strategy was developed to rapidly realize detection of bacteria activity (with Salmonella typhimurium, S.T, as a model analyte). Firstly, the composite probes, including deactivated phage modified magnetic beads and nano Pt-antimicrobial peptide (AMP) which can specifically recognize Gram-negative bacteria as nanozyme were prepared. When the composite probes are introduced into the chip together with target bacteria, after enrichment, oscillating and magnetic separation, they will conjugate with S.T and produce a magnetic sandwich complex. The complex can catalyze tetramethylbenzidine (TMB)-H2O2 to produce visible colorimetric signals which is correspondent to the total S.T content. Simultaneously, PtNPs in the complex can produce hydroxyl radical oxidation (∙OH) by decomposing H2O2. Under the synergistic action of ∙OH and AMP, the captured live S.T can be lysed to release ATP and emit bioluminescence signals which corresponds to the live S.T concentration. Therefore, the chip can simultaneously detect and image S.T at different viability in one test. The dual-mode assay demonstrated high sensitivity (≤33 CFU/mL), high specificity (identifying strain), signal amplification (5 folds) and short time (≤40min). The chip array can detect four samples in one test and exhibited advantages of high-integration, -sensitivity, -specificity and miniaturization, which are suitable to rapidly detect and image pathogen's viability in trace level. The replacement of phage probes can detect other bacteria. It has a wide prospect in pathogens screening.

Rapid and sensitive electrochemiluminescence detection using easily fabricated sensor with an integrated two-electrode system.

The electrochemiluminescence (ECL) behavior of a tri(2,2'-bipyridyl)ruthenium(ii) (Ru(bpy)32+)/tripropylamine (TPrA) system was investigated in sensor chips with two kinds of integrated two-electrode systems, which included screen-printed electrodes (SPE) and physical vapor deposition (PVD) electrodes. Firstly, under excitation with an optimal transient potential (TP) within 100 ms, the ECL assay could be carried out on the microchips using an Au & Au electrode system, emitting strong and stable light signal. Secondly, on the PVD chip, the ECL intensity initiated by optimal TP was eight times stronger than the peak light signal emitted by the linear sweep voltammetry model. Finally, the logarithmic ECL intensities exhibited a linear increase with the logarithmic concentrations of Ru(bpy)32+ in both the SPE and PVD chips without any reference electrode (RE). Typically, the integration of an interdigital two-electrode system in the microchip significantly enhanced the ECL sensitivity of Ru(bpy)32+ because the large relative area between the working electrode (WE) and counter electrode (CE) achieved a highly efficient mass transfer. This improvement enabled the establishment of a reliable linear relationship across a wide concentration range, spanning from 1 pM to 1 µM (R2 = 0.998). Therefore, the exceptional ECL response of the Ru(bpy)32+/TPrA system on microfluidic chips using a two-electrode system and the TP excitation model has been demonstrated. This suggests that ECL chips without a RE have broad potential for the rapid and sensitive detection of multiple targets.

Copper-Promoted N-Alkylation and Bromination of Arylamines/Indazoles Using Alkyl Bromides as Reagents for Difunctionalization.

Practical copper-promoted N-alkylation and bromination of arylamines/indazoles with alkyl bromides are described; the N-alkylation-C-4-bromination and N-dialkylation-C-4-bromination of arylamines, and N-alkylation-C-3-bromination of indazoles, with alkyl bromides have been analyzed. The full use of alkyl bromides as alkylating and brominating building blocks without atom wastage, indicating excellent atom and step economy, has been highlighted. Eco-friendly oxygen and water are the reaction oxidant and byproduct, respectively.

LncRNA NORAD accelerates the progression of non-small cell lung cancer via targeting miRNA-455/CDK14 axis.

BACKGROUND: To explore the potential involvement of long non-coding RNA (lncRNA) NORAD in regulating the progression of Non-small cell lung cancer (NSCLC), and its possible mechanism. METHODS: Relative level of NORAD in NSCLC tissues and cell lines was determined. Its level in NSCLC patients with different tumor staging (T1-T2, T3-T4) and either with lymphatic metastasis or not was examined as well. Kaplan-Meier curves were depicted for assessing the prognostic value of NORAD in NSCLC. Regulatory effects of NORAD on the proliferative ability of NCI-H1650 and HCC827 cells were evaluated. Dual-luciferase reporter gene assay was conducted to identify the binding between NORAD and miRNA-455, as well as between miRNA-455 and CDK14. At last, the role of NORAD/miRNA-455/CDK14 regulatory loop in influencing the progression of NSCLC was determined. RESULTS: NORAD was upregulated in NSCLC tissues and cells. Its level was higher in NSCLC patients with advanced stage or accompanied with lymphatic metastasis. Worse prognosis was observed in NSCLC patients presenting high level of NORAD. Silence of NORAD attenuated the proliferative ability of NCI-H1650 and HCC827 cells. MiRNA-455 was the downstream target binding to NORAD. Its level was negatively regulated by NORAD. Knockdown of miRNA-455 could reverse the role of NORAD in regulating the proliferative ability of NSCLC. Moreover, CDK14 was the target gene of miRNA-455. CDK14 level was negatively regulated by miRNA-455. CONCLUSIONS: LncRNA NORAD is upregulated in NSCLC, which enhances the proliferative ability of tumor cells by targeting miRNA-455/CDK14 axis and thereby accelerates the progression of NSCLC.

Rapid assembly of α-ketoamides through a decarboxylative strategy of isocyanates with α-oxocarboxylic acids under mild conditions.

A simple and practical method for α-ketoamide synthesis via a decarboxylative strategy of isocyanates with α-oxocarboxylic acids is described. The reaction proceeds at room temperature under mild conditions without an oxidant or an additive, showing good substrate scope and functional compatibility. Moreover, the applicability of this method was further demonstrated by the synthesis of various bioactive molecules and different application examples through a two-step one-pot operation.

Artificial modulation of cell width significantly affects the division time of Escherichia coli.

Bacterial cells have characteristic spatial and temporal scales. For instance, Escherichia coli, the typical rod-shaped bacteria, always maintains a relatively constant cell width and cell division time. However, whether the external physical perturbation of cell width has an impact on cell division time remains largely unexplored. In this work, we developed two microchannel chips, namely straight channels and 'necked' channels, to precisely regulate the width of E. coli cells and to investigate the correlation between cell width and division time of the cells. Our results show that, in the straight channels, the wide cells divide much slower than narrow cells. In the 'necked' channels, the cell division is remarkably promoted compared to that in straight channels with the same width. Besides, fluorescence time-lapse microscopy imaging of FtsZ dynamics shows that the cell pre-constriction time is more sensitive to cell width perturbation than cell constriction time. Finally, we revealed a significant anticorrelation between the death rate and the division rate of cell populations with different widths. Our work provides new insights into the correlation between the geometrical property and division time of E. coli cells and sheds new light on the future study of spatial-temporal correlation in cell physiology.

Copper-catalyzed [2+3]-annulation of N-H imines with vinyl azides: access to polyaryl 2H-imidazoles.

A practical method for the synthesis of 2H-imidazoles via a [2+3] annulation of N-H imines with vinyl azides using a copper catalyst is developed. In this conversion, environmentally friendly oxygen is used as the sole oxidant and N2 and H2O are the only by-products. The catalytic transformation, operating under mild conditions, is operationally simple and is considered as a readily available catalytic system having good substrate and functional compatibility with high atom-efficiency without the need for additional ligands or additives.

Compression Generated by a 3D Supracellular Actomyosin Cortex Promotes Embryonic Stem Cell Colony Growth and Expression of Nanog and Oct4.

Mechanical factors play critical roles in mammalian development. Here, we report that colony-growing mouse embryonic stem cells (mESCs) generate significant tension on the colony surface through the contraction of a three-dimensional supracellular actomyosin cortex (3D-SAC). Disruption of the 3D-SAC, whose organization is dependent on the Rho/Rho-associated kinase (ROCK) signals and E-cadherin, results in mESC colony destruction. Reciprocally, compression force, which is generated by the 3D-SAC, promotes colony growth and expression of Nanog and Oct4 in mESCs and blastocyst development of mouse embryos. These findings suggest that autonomous cell forces regulate embryonic stem cells fate determination and provide insight regarding the biomechanical regulation of embryonic development.