Service Reliability Test Method for Anticorrosion Coatings on the Compressor Outlet Pipelines of Natural Gas Stations.

Compressor outlets are subject to high temperatures and vibrations; when pipelines are subject to such conditions, degradation of the anticorrosive layer on the pipeline is likely. Fusion-bonded epoxy (FBE) powder coating is the most common type of anticorrosion coatings on compressor outlet pipelines. It is necessary to study the reliability of anticorrosive layers in compressor outlet pipelines. In this paper, a service reliability test method for the corrosion-resistant coatings of compressor outlet pipelines of natural gas stations is proposed. Testing involving the simultaneous exposure of the pipeline to high temperatures and vibrations is conducted to evaluate, on a compressed timescale, the applicability and service reliability of FBE coatings. The failure mechanism of FBE coatings exposed to high temperatures and vibrations is analyzed. It is found that, due to the influence of initial imperfections in the coatings, FBE anticorrosion coatings typically do not meet the standard requirements for use in compressor outlet pipelines. After simultaneous exposure to high temperatures and vibrations, the impact resistance, abrasion resistance, and bending resistance of the coatings are found not to meet the requirements for their intended applications. It is therefore suggested that FBE anticorrosion coatings be used with extreme caution in compressor outlet pipelines.

Aptamer-functionalised metal-organic frameworks as an 'on-off-on' fluorescent sensor for bisphenol S detection.

Bisphenol S (BPS) is an industrial chemical that is widely used to manufacture daily items, such as plastic water bottles, milk bottles, water cups, and paper products. BPS is a biologically toxic environmental endocrine disruptor. Long-term exposure to BPS can disrupt the reproductive system, endanger health, and increase the risk of cancer. The metal-organic framework UiO-66 is characterised with high thermal and chemical stability, a simple synthetic route, and low preparation cost. In this study, we modified UiO-66 with nucleic acid aptamers to prepare an 'on-off-on' fluorescent sensor for the simple and rapid detection of BPS. The FAM-labelled aptamer was selected as the fluorescent probe (i.e. 'on'). In the presence of UiO-66, the FAM-labelled aptamer adsorbed onto the surface of the UiO-66 material, and the fluorescence of FAM was quenched by photoinduced electron transfer (i.e. 'off'). When BPS was introduced into the system, the configuration of the FAM-labelled aptamer changed after binding to BPS, and the adsorption of FAM on UiO-66 weakened, resulting in fluorescence recovery (i.e. 'on'). Based on this principle, the reaction system was optimised, and the BPS content was analysed according to the change in the fluorescence signal. The signals changed linearly in the BPS concentration range of 2.0 × 10-4-4.0 × 10-2 mmol L-1, and the system had a detection limit of 1.84 × 10-4 mmol L-1. The sensor was successfully used to detect the BPS content in commercial plastic bottled water.

Sensitive fluorescent biosensor based on a europium-based metal-organic framework for protein kinase activity analysis.

Protein kinases play crucial regulatory roles in the physiological activities in the human body. Understanding protein kinase activity and its inhibition is essential for the management of human diseases. Considering the limitations of the existing protein kinase-related analysis methods, the aim of the present study was to develop a fluorescent biosensor based on Eu(BTC) (H2O)6 (BTC = 1,3,5-Benzenetricarboxylic acid) for evaluating protein kinase activity and the relevant inhibitors. A fluorophore-labelled substrate polypeptide was phosphorylated under the catalysis of protein kinase. This phosphorylated peptide can be coordinated explicitly with the europium site of Eu(BTC) (H2O)6 to detect the protein kinase. The developed biosensor performed well, with a detection limit of 0.00003 U µL-1, and it showed good selectivity and universality. Protein kinase activity could also be detected in MCF-7 cells using this method. Furthermore, in terms of inhibitor screening using the Eu(BTC) (H2O)6-based sensor, both H-89 and ellagic acid were found to inhibit protein kinase activity with IC50 values of 1.09 and 19.88 nmol L-1, respectively. Overall, this biosensor has broad application prospects in monitoring and controlling protein kinase activity.

Highly Sensitive and Selective Detection of Heparin in Serum Based on a Long-Wavelength Tetraphenylethylene-Cyanopyridine Aggregation-Induced Emission Luminogen.

A positively charged aggregation-induced emission luminogen (AIEgen), TPE-P+, was constructed by linking a pyridyl cation to tetraphenylethylene (TPE) via a cyanoethylene bond. TPE-P+ can realize the identification of heparin (Hep) by aggregating with negatively charged Hep via electrostatic interactions. Upon addition of Hep, TPE-P+ exhibited 36-fold fluorescence enhancement in less than 5 s, exhibiting quick and sensitive response to Hep with a low detection limit down to 4 nM. Among various biological substances, even Hep analogs like chondroitin 4-sulfate and hyaluronic acid, TPE-P+ showed the most significant fluorescence enhancement to Hep only, demonstrating its excellent selectivity for Hep. In particular, with long-wavelength emission near 600 nm and large stocks shift (∼160 nm), TPE-P+ enabled minimization of autofluorescence interference from a complex biological matrix and provided more accurate results. Finally, TPE-P+ was successfully applied for sensitive and selective detection of Hep in serum. Notably, there existed a good linear relationship in a serum assay when the Hep concentration ranging from 0 to 4 µM (R2 = 0.9934) covered the clinical dosage level during both cardiovascular surgery and long-term care, suggesting the potential clinical practice for quantifying Hep in serum. Moreover, TPE-P+-Hep complex can be further disaggregated by protamine (PRTM) due to the stronger affinity between Hep and PRTM, thereby leading to further detection of PRTM effectively. Last, but not least, the "off-on-off" system designed for both Hep and PRTM detection proved to be reversible.

Turn-on theranostic fluorescent nanoprobe by electrostatic self-assembly of carbon dots with doxorubicin for targeted cancer cell imaging, in vivo hyaluronidase analysis, and targeted drug delivery.

This paper reports a turn-on theranostic fluorescent nanoprobe P-CDs/HA-Dox obtained by electrostatic assembly of polyethylenimine (PEI)-modified carbon dots (P-CDs) and Hyaluronic acid (HA)-conjugated doxorubicin (Dox) for hyaluronidase (HAase) detection, self-targeted imaging and drug delivery. P-CDs/HA-Dox show weak emission in a physiological environment. By utilizing the high affinity of HA to CD44 receptors overexpressed on many cancer cells, P-CDs/HA-Dox are capable of targeting and penetrating into cancer cells, where they are activated by HAase. As a result, HA-Dox can be digested into small fragments, causing the release of Dox and thereby restoring the fluorescence of P-CDs. The theranostic fluorescent nanoprobe can effectively distinguish cancer cells from normal cells. The as-prepared nanoprobe achieves a sensitive assay of HAase with a detection limit of 0.65UmL-1. Furthermore, upon Dox release, the Dox could efficiently induce apoptosis in HeLa cells, as confirmed by MTT assay. The design of such a turn-on theranostic fluorescent probe provides a new strategy for self-targeted and image-guided chemotherapy.

Reversible and Dynamic Fluorescence Imaging of Cellular Redox Self-Regulation Using Fast-Responsive Near-Infrared Ge-Pyronines.

Cellular self-regulation of reactive oxygen species (ROS) stress via glutathione (GSH) antioxidant repair plays a crucial role in maintaining redox balance, which affects various physiological and pathological pathways. In this work, we developed a simple yet effective strategy for reversible, dynamic, and real-time fluorescence imaging of ROS stress and GSH repair, based on novel Ge-pyronine dyes (GePs). Unlike the current O-pyronine (OP) dye, the fluorescence of GePs can be quenched in GSH reduction and then greatly restored by ROS (e.g., ClO(-), ONOO(-), and HO(•)) oxidation because of their unique affinity toward thiols. The "on-off" and "off-on" fluorescence switch can complete in 10 and 20 s, respectively, and exhibit excellent reversibility in vitro and in cells. GePs also show excitation in the long wavelength from the deep-red to near-infrared (NIR) (621-662 nm) region, high fluorescence quantum yield (Φ(fl) = 0.32-0.44) in aqueous media, and excellent cell permeability. Our results demonstrated that GePs can be used for real-time monitoring of the reversible and dynamic interconversion between ROS oxidation and GSH reduction in living cells. GePs might be a useful tool for investigating various redox-related physiological and pathological pathways.