IRF4 induces M1 macrophage polarization and aggravates ulcerative colitis progression by the Bcl6-dependent STAT3 pathway.

Ulcerative colitis (UC) is an idiopathic chronic intestinal inflammation. An increasing body of evidence shows that macrophages play an important role in the pathogenesis of UC. Interferon regulatory factor 4 (IRF4) is crucial for the development of autoimmune diseases via regulating immune cells. This research was designed to explore the function of IRF4 in UC and its association with macrophage polarization. The in vitro model of UC was established by stimulating colonic epithelial cells with tumor necrosis factor α (TNF-α). A mouse model of UC was constructed by injecting C57BL/6 mice with dextran sulfate sodium salt. Flow cytometry was used to assess percentage of CD11b+ CD86+ and CD11b+ CD206+ cells in bone marrow macrophages. Occult blood tests were used to detect hematochezia. Hematoxylin and eosin staining assay was used to assess colon pathological changes. Enzyme-linked immunosorbent assay (ELISA) was used to detect concentrations of inflammatory cytokines. The interaction of IRF4 and B-cell lymphoma 6 (Bcl6) was confirmed using GST pull-down and coimmunoprecipitation assays. Our findings revealed that IRF4 promoted cell apoptosis and stimulated M1 macrophage polarization in vitro. Furthermore, IRF4 aggravated symptoms of the mouse model of UC and aggravated M1 macrophage polarization in vivo. IRF4 negatively regulated Bcl6 expression. Downregulation of Bcl6 promoted apoptosis and M1 macrophage polarization in the presence of IRF4 in vitro and in vivo. Moreover, Bcl6 positively mediated the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway. In conclusion, IRF4 aggravated UC progression through promoting M1 macrophage polarization via Bcl6/JAK2/STAT3 pathway. These findings suggested that IRF4 might be a good target to competitively inhibit or to treat with UC.

Nanoassemblies Based on a Cationic Perylene Diimide Derivative and Sodium Dodecyl Sulfate: A Simple Fluorescent Platform for Efficient Analysis of Aflatoxin B1.

Aflatoxin B1 (AFB1) is a kind of potently carcinogenic fungal metabolite in food threatening human health, and it is crucial and challenging to develop advanced nonimmune approaches for AFB1 determination. Addressing this challenge, we successfully constructed a nanoassembly (PdE-PDI/SDS) by noncovalently coupling a cationic perylene diimide derivative (PdE-PDI) and sodium dodecyl sulfate (SDS), exhibiting high-density charges and a specific surface area for rapid sensing of AFB1. The large electronic conjugate structure and rigid plane of PdE-PDI enable it to form more stable σ-π, π-π coordination, and hydrogen bonds with AFB1. Additionally, the introduction of SDS significantly amplifies noncovalent interactions and enhances the quenching efficiency of PdE-PDI toward AFB1. The proposed PdE-PDI/SDS exhibited excellent specificity to AFB1 and showed dosage-sensitive detection with detection limit as low as 0.74 ng mL-1. Finally, the PdE-PDI/SDS was successfully applied in cereal samples with good recoveries from 94.61 to 109.92%. To our knowledge, this is the first time a fluorescent strategy from the point of self-assembly for AFB1 determination is reported, which holds great promise for wide applications of perylene diimide derivative in food safety.

Ultrasensitive Detection of Organophosphorus Pesticides Using Single-Molecule Conductance Measurement.

Detection of organophosphorus pesticides (OPs) with high sensitivity in environmental samples is of vital importance for environmental safety and human health. However, it remains a challenge to achieve fM (10-15 mol/L) sensitivity for detecting OPs. Herein, we developed an acetylcholinesterase sensor based on 3,3',5,5'-tetramethylbenzidine (TMB) combining an enzyme-mediated strategy and scanning tunneling microscopy break junction (STM-BJ). Benefiting from the enzyme inhibition kinetics of OPs and the customized spectral clustering analysis method, our new strategy achieved the detection of methamidophos (MTMP) with a limit of 10 aM (10-17 mol/L) and 3 times higher selectivity in mixed OPs. As applied to natural lake waters, it also exhibited high reproducibility, high stability, and good recovery. This work paves a new avenue toward the application of single-molecule conductance characterizations for biochemical analysis and environmental monitoring.

Fluorescent detection of tartrazine based on the supramolecular self-assembly of cationic perylene diimide.

A cationic perylene probe was designed and synthesized for sensitive determination of tartrazine. In the presence of tartrazine, the fluorescence of the perylene probe was quenched by efficient supramolecular self-assembly of the perylene derivate. The quenching is caused by the synergistic effect of noncovalent interactions including static electricity, π-π stacking, and hydrophobic interaction. Benefiting from these advantages, the probe exhibited excellent sensing performance to tartrazine within 2 min. The detection and quantification limit of tartrazine are as low as 2.42 and 8.07 nmol L-1, respectively, with a wide linear operation range from 15 to 500 nmol L-1. Most importantly, due to the high binding affinity (3.22 × 107 mol L-1) between the perylene probe and tartrazine, the sensing system shows great anti-interference capacity. Subsequently, the visualization application of the approach was evaluated by portable device, and the limits of detection for visual detection for test strip, membrane, and hydrogel were 0.5, 0.5, and 5 µmol L-1, respectively. The approach has been applied to monitor tartrazine in various food condiments with recoveries in the range 91.29-108.83%. As far as we know, this is the first report of using perylene-based probe for tartrazine determination, offering a promising strategy for the construction of perylene-based detection system in the field of food safety.

Single-Molecule Tunneling Sensors for Nitrobenzene Explosives.

The tunneling current through the single-molecule junctions principally offers the ultimate solution for chemical and biochemical sensing via the interactions between probes and target analytes at the single-molecule level. However, it remains unexplored to achieve the sensitive and selective detection of targeted analytes using single-molecule junction techniques due to the challenge in quantitative evaluation of sensing sensitivity and selectivity. Herein, we demonstrate a single-molecule tunneling sensor for the highly sensitive and selective detection of nitrobenzene explosives using scanning tunneling microscope break junction (STM-BJ). Taking advantage of π-π stacking interactions between the molecular probes and nitrobenzene explosives, we use a spectral clustering algorithm to assign the signal of probes and π-stacked probes for sensitively detecting the targeted analytes and the distinguishable conductance change of probes when interacting with different nitroaromatic explosive compounds for selective detection. We find that pronounced conductance changes up to 0.8 orders of magnitude when the probes interact with TNT. Also, we obtain a sensitivity of up to ∼10 pM for TNT and high sensitivity for eight TNT analogues. Combined with theoretical calculations, we discover that the harness of the destructive quantum interference of the probe M1OH after interacting with TNT leads to high selectivity in sensing with TNT. Our work demonstrates the great potential of the single-molecule tunneling current for environmental sensing molecules with high selectivity and sensitivity.

A fluorometric and colorimetric approach for the rapid detection of berberine hydrochloride based on an anionic polythiophene derivative.

In this report, we develop a dual-output sensor with fluorometric and colorimetric responses, for the rapid and simple detection of berberine hydrochloride (BRH) in 100% aqueous solution based on an anionic polythiophene derivative, poly(2-(2-(4-methylthiophen-3-yloxy)-ethyl) malonic acid) (PTMA). The sensing performance and mechanism were carefully examined by absorption and emission spectra. It can be applied to quantitatively detect BRH in aqueous solution with a detection limit 0.27 µM. The appealing performance of the sensor was demonstrated to originate from the electrostatic and π-π interactions between PTMA and BRH, which promoted the conformational change and aggregation of the PTMA backbone. Moreover, this method allowed rapid detection of BRH in urine samples and BRH tablets with high accuracy.

Visual detection of fluoride based on supramolecular aggregates of perylene diimide in 100% aqueous media.

A water-soluble perylene imide derivative (PDI-Glu) was synthesized and their supramolecular aggregates composed of PDI-Glu and Al3+ were prepared as a "turn on" fluorometric probe to monitor F- in a purely aqueous system. Based on an "indicator displacement assay" (IDA) approach, the sensing performance and mechanism of PDI-Glu/Al3+ complex toward F- were investigated by absorption and emission spectra. It was suggested that disassembly of PDI-Glu/Al3+ aggregates was promoted by addition of F- through the competitive binding between Al3+ and F-. The detection limit is 240 nmol/L. This method featured simple preparation, excellent water solubility, adjustable self-assembly performance, ease of observation and operation, and high selectivity and sensitivity. It was used for monitoring F- in toothpaste and tap water samples with excellent accuracy and recovery. To the best of our knowledge, this is the first water-soluble perylene diimide-based probe for F- detection in 100% aqueous media. We believe this work could not only extend the sensing scope of water-soluble perylene diimide, but also bring some useful information for the rapid detection of anionic analytes  in aqueous media. The disassembly of supramolecular aggregates of PDI-Glu/Al3+ along with significant fluorescence recovery enable a rapid and visual detection of F- based on an "indicator displacement assay" strategy.

Inhibition of Autophagy by a Small Molecule through Covalent Modification of the LC3 Protein.

The autophagic ubiquitin-like protein LC3 functions through interactions with LC3-interaction regions (LIRs) of other autophagy proteins, including autophagy receptors, which stands out as a promising protein-protein interaction (PPI) target for the intervention of autophagy. Post-translational modifications like acetylation of Lys49 on the LIR-interacting surface could disrupt the interaction, offering an opportunity to design covalent small molecules interfering with the interface. Through screening covalent compounds, we discovered a small molecule modulator of LC3A/B that covalently modifies LC3A/B protein at Lys49. Activity-based protein profiling (ABPP) based evaluations reveal that a derivative molecule DC-LC3in-D5 exhibits a potent covalent reactivity and selectivity to LC3A/B in HeLa cells. DC-LC3in-D5 compromises LC3B lipidation in vitro and in HeLa cells, leading to deficiency in the formation of autophagic structures and autophagic substrate degradation. DC-LC3in-D5 could serve as a powerful tool for autophagy research as well as for therapeutic interventions.

Rapid and visual detection of berberine hydrochloride based on a water-soluble pyrene derivative.

In this study, a rapid method for the detection of berberine hydrochloride (BRH) was developed based on a water-soluble pyrenyl probe, 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS). This method features low cost, good selectivity, high sensitivity and a fast response. The sensing mechanism of this probe is attributed to the formation of a complex between HPTS and BRH induced by electrostatic interaction and π-π stacking. To the best of our knowledge, this is the first fluorescent sensor for BRH based on organic materials that has low cost and a visual response. The detection limit of this method was as low as 1.24 µM and the linear response range is 2-50 µM. This method also allowed rapid detection of BRH real samples.

Rapid and visual detection of heparin based on the disassembly of polyelectrolyte-induced pyrene excimers.

We have developed a ratiometric sensor based on polyelectrolyte-induced pyrene excimers for the rapid and visual detection of heparin in aqueous media. This sensor has a simple preparation method, fast response, low cost, and high sensitivity and selectivity. As a complementary strategy for the detection of heparin based on the formation of pyrene excimers, this approach could identify heparin specifically over chondroitin sulphate, which is the major interferent in most sensing systems for the detection of heparin. The detection limit of this approach can be as low as 0.14 µM using fluorescence measurements. To the best of our knowledge, this is among the lowest LOD for the detection of heparin reported in the literature. It enables the rapid and visual detection of heparin both in buffered solution and serum samples.

Approach Based on Polyelectrolyte-Induced Nanoassemblies for Enhancing Sensitivity of Pyrenyl Probes.

We have developed a unique approach for enhancing the sensitivity of pyrenyl probes based on polyelectrolyte-induced nanoassemblies and explored its sensing application toward 2,4,6-trinitrophenol (TNP). The key issue of the method is the formation of the nanoassemblies which possess high-density charges, specific surface area, and inner hydrophobic regions. These properties would help increase the loading of analytes and promote probe-analyte interactions, thereby leading to the prominent enhancement of the sensitivity. In the course of TNP detection, pyrene nanoassemblies can bind TNP efficiently through cooperative noncovalent interactions including electrostatic, π-π stacking, and charge-transfer interactions, resulting in the distinct fluorescent responses of pyrene moieties. This system has excellent selectivity and sensitivity for TNP detection. The detection limit is as low as 5 nM. It may be used for monitoring the TNP concentrations in real-world samples.

Identification of novel EZH2 inhibitors through pharmacophore-based virtual screening and biological assays.

Polycomb repressive complex 2 (PRC2) acts as a primary writer for di- and tri-methylation of histone H3 at lysine 27. This protein plays an essential role in silencing gene expression. Enhancer of zeste 2 (EZH2), the catalytic subunit of PRC2, is considered as a promising therapeutic target for cancer. GSK126, a specific inhibitor of EZH2, is undergoing phase I trials for hypermethylation-related cancers. In addition, many derivatives of GSK126 are also commonly used in laboratory investigations. However, studies on the mechanism and drug development of EZH2 are limited by the absence of structural diversity of these inhibitors because they share similar SAM-like scaffolds. In this study, we generated a pharmacophore model based on reported EZH2 inhibitors and performed in silico screenings. Experimental validations led to the identification of two novel EZH2 inhibitors, DCE_42 and DCE_254, with IC50 values of 23 and 11µM, respectively. They also displayed significant anti-proliferation activity against lymphoma cell lines. Thus, we discovered potent EZH2 inhibitors with novel scaffold using combined in silico screening and experimental study. Results from this study can also guide further development of novel specific EZH2 inhibitors.

Identification of Novel Disruptor of Telomeric Silencing 1-like (DOT1L) Inhibitors through Structure-Based Virtual Screening and Biological Assays.

Histone methyltransferases are involved in many important biological processes, and abnormalities in these enzymes are associated with tumorigenesis and progression. Disruptor of telomeric silencing 1-like (DOT1L), a key hub in histone lysine methyltransferases, has been reported to play an important role in the processes of mixed-lineage leukemia (MLL)-rearranged leukemias and validated to be a potential therapeutic target. In this study, we identified a novel DOT1L inhibitor, DC_L115 (CAS no. 1163729-79-0), by combining structure-based virtual screening with biochemical analyses. This potent inhibitor DC_L115 shows high inhibitory activity toward DOT1L (IC50 = 1.5 µM). Through a process of surface plasmon resonance-based binding assays, DC_L115 was founded to bind to DOT1L with a binding affinity of 0.6 µM in vitro. Moreover, this compound selectively inhibits MLL-rearranged cell proliferation with an IC50 value of 37.1 µM. We further predicted the binding modes of DC_L115 through molecular docking analysis and found that the inhibitor competitively occupies the binding site of S-adenosylmethionine. Overall, this study demonstrates the development of potent DOT1L inhibitors with novel scaffolds.

A simple fluorescent probe based on a pyrene derivative for rapid detection of protamine and monitoring of trypsin activity.

We report the synthesis of a simple pyrene derivative and its application in protamine detection and monitoring of trypsin activity. This assay can be conducted in aqueous solution and features rapid response, visual detection, high sensitivity and selectivity. The limit of detection of protamine was 0.5 µg mL(-1). The IC50 value of a soybean trypsin inhibitor was estimated to be 0.51 U mL(-1).

Biological evaluation of new antitumor taxoids: alteration of substitution at the C-7 and C-10 of docetaxel.

A series of new docetaxol analogues have been designed and synthesized. And their cytotoxicities against cancer cells have been evaluated by MTT method. Most of these compounds showed selective inhibitions on human cancer cell lines. Among them, compound 8 exhibited higher inhibitory activity than Paclitaxel (Taxol) against several cancer cell lines. This work indicated that appropriate modification at C-7 and C-10 of docetaxel might be a promising approach for this unique class of anticancer compounds.

A colorimetric probe for rapid and simultaneous detection of alkylresorcinols and ferulic acid based on in-situ coupling reaction in aqueous media.

Rapid and simultaneous detection of Alkylresorcinols (ARs) and ferulic acid (FA) could evaluate qualities of commercial wheat products comprehensively and improving product quality. In this work, we have developed a colorimetric strategy for rapid and simultaneous detection of ARs and FA by using in-situ coupling reaction between analytes and diazotized small molecule probe in aqueous media. This strategy featured a rapid response, obvious color change, simple preprocessing, high sensitivity and selectivity. The limit of detection (LOD) can be as low as 0.244 µM and 0.5 µM for ARs and FA, respectively. The sensing mechanism was investigated by spectroscopy technique. Excellent practical application of this method was further confirmed to simultaneously monitor ARs and FA in real samples. The accuracy of the method could be reached to 95.0 % and 99.6 % for ARs and FA respectively. To our knowledge, this work firstly reported a sensor for ARs and FA simultaneous determination.

A General Strategy for Food Traceability and Authentication Based on Assembly-Tunable Fluorescence Sensor Arrays.

Food traceability and authentication systems play an important role in ensuring food quality and safety. Current techniques mainly rely on direct measurement by instrumental analysis, which is usually designed for one or a group of specific foods, not available for various food categories. To develop a general strategy for food identification and discrimination, a novel method based on fluorescence sensor arrays is proposed, composed of supramolecular assemblies regulated by non-covalent interactions as an information conversion system. The stimuli-responsiveness and tunability of supramolecular assemblies provided an excellent platform for interacting with various molecules in different foods. In this work, five sensor arrays constructed by supramolecular assemblies composed of pyrene derivatives and perylene derivatives are designed and prepared. Assembly behavior and sensing mechanisms are investigated systematically by spectroscopy techniques. The traceability and authentication effects on several kinds of food from different origins or grades are evaluated and verified by linear discriminant analysis (LDA). It is confirmed that the cross-reactive signals from different sensor units encompassing all molecular interactions can generate a unique fingerprint pattern for each food and can be used for traceability and authentication toward universal food categories with 100% accuracy.

Visual detection of copper(II) ions based on an anionic polythiophene derivative using click chemistry.

We have developed a novel approach for the rapid visual detection of Cu(2+) based on an anionic polythiophene derivative (sodium poly(2-(4-methyl-3-thienyloxy)propanesulfonate, PMTPS) using click chemistry. The method relies on the disassembly of PMTPS aggregates in the presence of cationic surfactant through electrostatic and hydrophobic interactions. In the assay of Cu(2+) detection, a cationic surfactant was formed via a click reaction catalyzed by copper(I), which was derived in situ from copper(II) and promoted the disassembly of PMTPS aggregates leading to the distinct solution color change from purple to yellow. This polymer probe has excellent sensitivity and selectivity for Cu(2+) with a detectable range in the micromolar regime by naked eyes and can be used for monitoring Cu(2+) concentrations below the safety limit in real-world samples.

Highly sensitive simultaneous detection of lead(II) and barium(II) with G-quadruplex DNA in α-hemolysin nanopore.

Both Pb(2+) and Ba(2+) can bind with high affinity to some specific DNA sequences, inducing the formation of unimolecular G-quadruplex structures. Translocation of a DNA probe containing such sequences through an α-hemolysin nanopore in the presence of Pb(2+) or Ba(2+) would result in much prolonged DNA translocation events. Quantification of these events can reveal the concentrations of Pb(2+) or Ba(2+) at as low as 0.8 nM. Besides, Pb(2+) and Ba(2+) in the solution can be simultaneously detected and individually identified. Furthermore, the probe is highly selective for Pb(2+) and Ba(2+) detection without interference from other metal ions. This sensing strategy can be extended to many other analytes which can bind to DNA molecules with high affinity.

Colorimetric detection of copper ions based on a supramolecular complex of water-soluble polythiophene and ATP.

A colorimetric probe for the detection of copper(II) ions in aqueous media by the naked eye has been developed based on a supramolecular complex comprised of a cationic polythiophene derivative and ATP with a detection limit as low as 0.05 mM.