Correction to " Application of Terahertz Nondestructive Testing Technology in the Detection of Polyethylene Pipe Defects".

[This corrects the article DOI: 10.1021/acsomega.3c02701.].

Application of Terahertz Nondestructive Testing Technology in the Detection of Polyethylene Pipe Defects.

At present, polyethylene pipeline is widely used in urban gas projects, but a relatively mature and reliable nondestructive testing technology has not been formed. Therefore, it is urgent to develop a new nondestructive testing technology to meet the increasing demand for inspection of non-metallic pipes. The terahertz testing technology and related equipment have played an increasingly important role in the nondestructive testing of many nonmetallic structures, but they have not been applied to polyethylene (PE) pipes. In this work, terahertz time-domain spectroscopy was used to detect prefabricated defects inside the PE pipe specimens. The results show that the terahertz nondestructive testing technology can be used to detect common defects in nonblack PE pipes with a detection error of less than 10%. Higher-power terahertz devices can detect defects in black PE pipe, while lower-power terahertz devices cannot. Because the black PE pipe contains carbon and has a strong absorption of terahertz waves. The penetration of lower-power terahertz devices to the black PE pipe is not enough, resulting in a low resolution of the imaging. The results of this work may promote the progress of the nondestructive testing technology of nonmetallic pipelines.

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 recognition-promoted hybridization chain reaction for amplified label-free and enzyme-free fluorescence analysis of pesticide.

Development of high-performance fluorescence sensors for pesticide is highly urgent but remains a grand challenge. It is due to that most of known fluorescence sensors detect pesticides based on enzyme-inhibited strategy, which requires high-price cholinesterase, suffers from serious interference of reductive materials, and can't difference pesticides with each other; the known aptamer-based fluorescence ones entail tool enzymes or nanomaterials to transducer/amplify the signal and demand signalers to be tagged in nucleic acid, which are expensive and intricate. Herein, we develop a novel aptamer-based fluorescence system for label-free, enzyme-free and highly sensitive detection of pesticide (profenofos) based on target-initiated hybridization chain reaction (HCR)-assisted signal amplification and specific intercalation of N-methylmesoporphyrin IX (NMM) in G-quadruplex DNA. Hairpin probe ON1 recognizes profenofos to generate profenofos@ON1 complex, which switches the HCR to yield multiple G-quadruplex DNA, consequently making large numbers of NMM be locked. In comparison with profenofos absence, a sharply improved fluorescence signal was recorded and it was dependent on profenofos dose. Hence, label-free, enzyme-free and highly sensitive detection of profenofos is achieved with limit of detection of 0.085 nM, which compared favorably with or superior to those of known fluorescence methods. Furthermore, the present method was applied to determine the profenofos residue in rice with agreeable result, and will provide more valuable information for guaranteeing the pesticide-related food safety.

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.

An AIE luminogen self-assembled nanoprobe for efficient monitoring of the concentration and structural transition of human serum albumin.

Monitoring the content and structural transition of human serum albumin (HSA) is valuable for diagnosing hypoalbuminemia and albuminuria and elucidating its transport function, respectively. Herein, we developed a multifunctional and efficient nanoprobe based on the self-assembly of an amphiphilic aggregation-induced emission luminogen, TPNN, for HSA detection and structure monitoring. TPNN molecules formed loose self-assembly in aqueous media and emitted faint fluorescence due to vigorous intramolecular motion. In the presence of HSA, a remarkable fluorescence enhancement accompanied by dissociation of TPNN assembly was observed due to the site-specific binding of TPNN to the middle long-narrow pocket of HSA. This binding blocked the intramolecular motion while producing a sensitive, selective, fast and stable fluorescence turn-on response to HSA, making TPNN assembly suitable for the HSA assay. TPNN assemblies also showed superior selectivity to HSA than bovine serum albumin (BSA) due to the distinct binding modes, and enabled us to distinguish the two homologous proteins. Furthermore, the generated TPNN-HSA complex underwent stepwise fluorescence quenching in the presence of protein denaturants and proteases, which revealed the process and kinetics of HSA unfolding and cleavage. TPNN assembly provides a powerful tool for accurate quantification of HSA in serum and urine and real-time monitoring of HSA structural transition.

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.

An electrostatically regulated organic self-assembly for rapid and sensitive detection of heparin in serum.

Heparin (Hep) is a highly negatively charged linear glycosaminoglycan involved in various physiological processes, especially blood coagulation. Hep is also a first-line drug for anticoagulation and prevention of thromboembolism, but its overdose will cause serious side effects. Herein, we designed a long-wavelength double-charged cationic fluorescent probe PYPN, and studied its aggregation state and detection performance for Hep. PYPN was readily synthesized through a one-step reaction without complicated purification. In aqueous medium, PYPN molecules with an amphiphilic structure spontaneously form nano-assemblies, which can be immediately decomposed by Hep due to the formation of a PYPN-Hep complex based on electrostatic attraction. The assembly shows a fast, sensitive and ratiometric fluorescence response to Hep, without being obviously interfered by other compounds. In various serum matrices, the fluorescence intensity ratio F610/F470 has a good linearity with Hep concentration (0-12 µg mL-1), and the detection limit (0.11-0.12 U mL-1) is lower than the minimum concentration (0.2 U mL-1) used in clinical treatment. Our study provides an easy-to-prepare and feasible tool for the selective and sensitive quantification of Hep in serum.

A review of dynamic multiaxial experimental techniques.

Structures and materials are usually exposed to exploding and attacking loading, experiencing large multiaxial plastic deformation under high strain rate; thus, experimental techniques under dynamic multiaxial loading are significant and practical. In this paper, the history and progress of dynamic multiaxial loading experiment techniques are reviewed, the key technical problems in the dynamic multiaxial testing are analyzed, and a feasible solution is proposed.

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.

Selective extraction and detection of ß-agonists in swine urine for monitoring illegal use in livestock breeding.

The illegal use of ß-agonists often endangers animal-derived food safety. In this study, a selective detection method for ß-agonists in swine urine was established via the combination of polymeric ionic liquid-molecularly imprinted graphene oxide-miniaturized pipette tip solid-phase extraction and high-performance liquid chromatography. It is worth noting that this method relied mainly on the designed adsorbent, which presented a rich adsorption mechanism, fast mass transfer rate, and high selectivity, and was successfully utilized in the selective extraction of ß-agonists from swine urine samples. The proposed method has low LOD (0.20-0.56 ng/mL), high recovery (94.9-107.9%), and high reusability (4 times, 91.9-108.8%), which indicates its high potential as a selective, sensitive, accurate, and nonfatal method for monitoring the illegal use of ß-agonists in the livestock breeding stage.

Screening and Isolating Major Aldose Reductase Inhibitors from the Seeds of Evening Primrose (Oenothera biennis).

Aldose reductase (AR) is a drug target for therapies to treat complications caused by diabetes mellitus, and the development of effective AR inhibitors (ARIs) of natural origin is considered to be an attractive option for reducing these complications. In this research, the rat lens AR (RLAR) inhibitory activity of evening primrose (Oenothera biennis) seeds was investigated for the first time. In our results, the 50% (v/v) methanol extract of evening primrose seeds exhibits excellent RLAR inhibitory activity (IC50 value of 7.53 µg/mL). Moreover, after enrichment of its bioactive components, the ARIs are more likely to be present in the ethyl acetate fraction of 50% (v/v) methanol extract (EME) of evening primrose seeds, which exhibits superior RLAR inhibitory activity (IC50 value of 3.08 µg/mL). Finally, gallic acid (1), procyanidin B3 (2), catechin (3), and methyl gallate (4) were identified as the major ARIs from the EME by affinity-based ultrafiltration-high-performance liquid chromatography and were isolated by high speed countercurrent chromatography, with gallic acid (11.46 µmol/L) and catechin (14.78 µmol/L) being the more potent inhibitors of the four ARIs identified. The results demonstrated that evening primrose seeds may be a potent ingredient of ARIs.

Cauliflower-like resin microspheres with tuneable surface roughness as solid-phase extraction adsorbent for efficient extraction and determination of plant growth regulators in cucumbers.

New cauliflower-like phloroglucinol-glyoxylic acid resin microspheres (PGRMs) with controllable diameters and tuneable surface roughness were prepared using a one-step environmentally-friendly method without a catalyst. The PGRMs obtained exhibited a rough surface, narrow size distribution, and excellent adsorption capacity for polar compounds. The PGRMs were employed as an adsorbent for solid phase extraction (SPE) of kinetin (KT) and 6-benzyladenine (6-BA) in cucumbers and demonstrated better extraction recoveries and purification efficiency than phloroglucin-formaldehyde resin and common commercial adsorbents. Our PGRMs-SPE-HPLC method showed good linearity (r ≥ 0.9997) ranging from 0.04 to 4.00 µg/g for KT and 6-BA, and recoveries at three spiked concentration ranged from 77.8% to 104.4% with RSDs ≤ 6.8%. This PGRMs-SPE-HPLC method was applied successfully to determine of KT and 6-BA in cucumbers.

An ESIPT based naphthalimide chemosensor for visualizing endogenous ONOO- in living cells.

Based on ESIPT, we designed and synthesized a naphthalimide chemosensor N-CBT for selectively visualizing endo/exogenous peroxynitrite (ONOO-) in living cells. The incorporation of 2-benzothiazoleacetonitrile offers N-CBT a rare pre-existing eight-membered ring hydrogen bonding configuration, which is able to generate two types of emission of naphthalimide. Confirmed by calculation results, fast proton transfer from the hydroxyl group to the carbonyl group occurs along with excited-state energy transfer via the intramolecular H-bond, leading to a tautomeric transformation from the excited enol form to the excited keto form. In aqueous solution, the formation of intermolecular hydrogen bonding with water perturbs ESIPT and destroys the stable planar construction. By breaking the cyano carbon-carbon double bond in the presence of ONOO-, green fluorescence can be regenerated efficiently. As a result, 34-fold fluorescence enhancement at 518 nm was observed in response, and it showed a good linear relationship in the range of 1 to 14 µM with a detection limit of 37 nM. Subsequently, N-CBT was applied in visualizing cellular ONOO-, and it demonstrated great potential in selectively visualizing endo/exogenous peroxynitrite (ONOO-) in living cells.

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.

An ultrafast responsive BODIPY-based fluorescent probe for the detection of endogenous hypochlorite in live cells.

Hypochlorite plays a significant role in various physiological and pathological processes; however, its role is still less clear than the role of other reactive oxygen species. Herein, we report an ultrafast responsive (<0.2 s) and highly selective probe B-Ts for hypochlorite with high sensitivity and a detection limit as low as 7.5 nM. The probe was compatible in a wide pH range of 4-13. More importantly, experiments in live cells showed that the probe could penetrate the cell membrane easily and was capable of imaging endogenous and exogenous hypochlorite specifically with a fast response.

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.

UV-assisted synthesis of long-wavelength Si-pyronine fluorescent dyes for real-time and dynamic imaging of glutathione fluctuation in living cells.

Changes in intracellular glutathione (GSH) concentration are closely linked with various cellular physiological and pathological mechanisms. In the present work, four long-wavelength Si-pyronine (SiP) fluorescent dyes are readily synthesized via a UV-assisted aromatization reaction, and used for real-time, dynamic and reversible monitoring of GSH changes in vitro and in living cells. Based on the mechanism that Si atom incorporation greatly increases the pyronine affinity towards sulfhydryl (-SH), SiPs can undergo ultrafast and reversible Michael addition with biological thiols, leading to fluctuations in fluorescence intensity due to the interruption and restoration of their π-conjugation. Relying on the unique reactivity of SiPs with GSH under physiological conditions, the fluorescence intensity of SiPs responds to GSH changes with high sensitivity. SiPs also exhibit excellent photophysical properties including deep-red to near-infrared excitation wavelength (>600 nm), a high fluorescence efficiency (0.20-0.41) in aqueous media, suitable water-solubility and membrane permeability. Using SiP-Pr to incubate with HeLa cells, we achieved real-time, dynamic and repeated imaging of fluctuations in intracellular GSH homeostasis under N-ethylmaleimide stimulation.