Preparation of copper nanoparticles fluorescent probes and detection of hydrogen peroxide and glucose.

Fluorescent copper nanoparticles (CuNPs) was synthesized by one-step chemical reduction method using ascorbic acid (AA) and copper sulfate (CuSO4⋅5H2O) as raw materials, which had good water solubility and fluorescence properties. A green, simple and safe CuNPs@Fe2+ fluorescence probe was developed for the detection of hydrogen peroxide and glucose using Fe2+ as a bridge. The prepared CuNPs could obtain the maximum fluorescence emission wavelength at 440 nm when the excitation wavelength was 360 nm. The average particle size of CuNPs was 10 nm, which had good photobleach resistance, stability and salt tolerance. The fluorescence intensity was quenched due to electron transfer (ET) process when hydrogen peroxide was added to CuNPs@Fe2+ system. This result was mainly because Fenton reaction occured between hydrogen peroxide and Fe2+, producing hydroxyl free radicals (OH) and Fe3+. Since glucose could be catalyzed by specific glucose oxidase (GOX) to produce H2O2 and corresponding oxidation products, the quantitative analysis of glucose was realized when glucose oxidase was introduced into the CuNPs@Fe2+ sensor system. Therefore, a novel CuNPs@Fe2+ fluorescent probe sensor study was constructed to further achieve quantitative detection of H2O2 and glucose. Under the optimized experimental conditions, the linear ranges for H2O2 and glucose were 28.219-171.562 µM and 1.237-75.771 µM, respectively. And the detection limits for H2O2 and glucose were 7.169 µM and 0.540 µM, respectively. In addition, the mechanism of fluorescence probe quenching caused by the interaction between H2O2 and CuNPs@Fe2+ was also discussed. The proposed sensing system had been applied successfully to the detection of glucose in human serum samples.

A signal-switchable fluorescent probe for detection of HPO4 2- based on 5,10,15,20-(4-sulphonatophenyl)porphyrin (TPPS4 ).

In this study, 5,10,15,20-(4-sulphonatophenyl)porphyrin (TPPS4 ) was selected as a fluorescent probe due to its excellent characteristics including high quantum yield, good water solubility, and exceptional biocompatibility. With an excitation wavelength set at 515 nm, the optimal fluorescence emission wavelength for TPPS4 was measured at 642 nm. At this moment, the fluorescence signal of TPPS4 pink solution was in the 'ON' state. The fluorescence intensity of TPPS4 was quenched when ascorbic acid (AA) was introduced, which was due to the electron transfer quenching effect between AA and TPPS4 . The colour of the corresponding solution changed from pink to green, and the fluorescence signal was in the 'OFF' state. When HPO4 2- was further introduced into the TPPS4 -AA system, the quenched fluorescence intensity of TPPS4 was recovered due to the unique interaction between HPO4 2- and AA. At this time, the colour of the corresponding solution changed from green to red, and the fluorescence signal was in the 'ON' state. Therefore, an 'ON-OFF-ON' signal-switchable fluorescent probe was constructed based on TPPS4 to detect HPO4 2- . The results showed that the linear range of HPO4 2- was 4.0 × 10-9 to 1.7 × 10-6  M, and the detection limit was 1.3 × 10-9  M (S/N = 3). The sensing system exhibited high accuracy and sensitivity, and it could be used successfully to detect HPO4 2- in real samples.

Novel "on-off" fluorescence sensing for rapid and accurate determination of Cr3+ based on g-CNQDs.

Cr3+ is one of the most essential trace elements in living organisms and plays a vital role in human metabolism. However, both deficiency and excess intake of Cr3+ can be harmful to the human body. Therefore, the quantitative determination of Cr3+ is of great significance in the field of life science. Based on this, in this study, a g-CNQDs@p-acetaminophenol fluorescence sensing system was developed for the quantitative detection of Cr3+ in actual complex samples. G-CNQDs were synthesized with sodium citrate and urea as precursors. The fluorescence signal was enhanced by the synergistic effect between p-acetaminophenol (APAP) and g-CNQDs. The fluorescence quenching phenomenon can be produced when Cr3+ is introduced into the fluorescence-enhanced g-CNQDs@p-acetaminophenol system. An "on-off" fluorescence sensing system was constructed based on g-CNQDs@p-acetaminophenol for the quantitative detection of Cr3+. The experimental data showed a wide linear region in the concentration range of 0.64-63.0 µM, and the detection limit was as low as 0.23 µM. The construction of the sensor system broadens the research field for the practical application of Cr3+.

Simultaneous fluorescence sensing of vitamin B2 and sulfur ions based on fluorescent copper nanoparticles.

In this study, the F-CuNPs were synthesized by a modified liquid-phase chemical reduction method. Throughout the preparation process, anhydrous copper sulfate was used as the copper source, and ascorbic acid in the NaOH solution served as the reducing and protective agent. Förster resonance energy transfer (FRET) may exist between F-CuNPs and vitamin B2 due to the large spectral overlap between the fluorescence emission spectra of F-CuNPs and the UV-vis absorption spectra of vitamin B2. Therefore, the detection of vitamin B2 was designed based on a FRET system between F-CuNPs and vitamin B2. With S2- into the F-CuNPs&VB2 system, the fluorescence intensity of vitamin B2 was quenched, while the fluorescence intensity of F-CuNPs was almost unchanged. There may be a specific reaction between S2- and vitamin B2. Therefore, the research system can be further used to detect S2- based on ratiometric fluorescent probe. The research findings show that the linear range of vitamin B2 was 0.51 nM-34.64 nM with a detection limit of 0.25 nM (S/N = 3), the linear range of S2- was 0.64 µM-60.00 µM with a detection limit of 0.32 µM (S/N = 3). Furthermore, the simultaneous fluorescent sensing system has high sensitivity and selectivity. Therefore, this system was designed and successfully used to detect the content of vitamin B2 and S2- in actual samples to find a new effective method to detect analytes.

A Calcium Phosphate-Induced Mouse Abdominal Aortic Aneurysm Model.

An abdominal aortic aneurysm (AAA) is a life-threatening cardiovascular disease that occurs worldwide and is characterized by irreversible dilation of the abdominal aorta. Currently, several chemically induced murine AAA models are used, each simulating a different aspect of the pathogenesis of AAA. The calcium phosphate-induced AAA model is a rapid and cost-effective model compared to the angiotensin II- and elastase-induced AAA models. The application of CaPO4 crystals to the mouse aorta results in elastic fiber degradation, loss of smooth muscle cells, inflammation, and calcium deposition associated with aortic dilation. This article introduces a standard protocol for the CaPO4-induced AAA model. The protocol includes material preparation, the surgical application of the CaPO4 to the adventitia of the infrarenal abdominal aorta, the harvesting of aortas to visualize aortic aneurysms, and histological analyses in mice.

Insights into the mechanism of carbon chain growth on zeolite-based Fischer-Tropsch Co/Y catalysts.

In a zeolite-based Fischer-Tropsch bifunctional catalyst, zeolites, as the support of the active metal, can interact with the metal cluster to affect the electronic properties and structural effect of the catalyst, thus affecting the Fischer-Tropsch synthesis reaction. In this work, the Fischer-Tropsch synthesis process using a Co catalyst supported by Y-zeolite was simulated by the DFT method from the microscopic point of view. The reaction network was designed to investigate the reaction mechanism in terms of four parts consisting of H-assisted CO dissociation, C1 hydrogenation, CHx-CHx coupling, and C2-C4 growth. It was found that the introduction of Y-zeolite enhanced the adsorption capacity of the catalyst for most species. Moreover, the catalytic mechanism of the Co/Y catalyst was clarified, and we found that the introduction of the Y-zeolite mainly reduced the reaction energy barriers of the CH-CH coupling and C2-C4 carbon chain growth process, which also explained the high proportion of long carbon chain hydrocarbons in the Fischer-Tropsch synthesis products after Y-zeolite was introduced.

High time-resolved characterization of airborne microbial community during a typical haze pollution process.

Variations of bioaerosol characteristics during the process of haze pollution have rarely been explored. In this study, high time-resolved variations of the community structures of bacteria, fungi, and ammonia-oxidizing microorganisms (AOMs) were assessed during a typical haze pollution process. The impacts of meteorological factors, water-soluble inorganic ions (WSII), and organic dicarboxylic acids (DCA) on the airborne microbial community were systematically evaluated. The results showed that the bacterial community varied greatly during the formation stages of haze pollution, and tended to stabilize with the further development of haze pollution. Nevertheless, variations of the fungal community lasted throughout the whole haze pollution process. Furthermore, Nitrososphaera absolutely dominated the ammonia-oxidizing archaea (AOA) and declined as PM2.5 burst. Network analysis identified relatively weak interactions and co-occurrence patterns between dominant fungal genera. Importantly, dust source ions and PM2.5 acidity exerted the most significant impacts on bacterial and fungal communities. These results identify the high time-resolved variations of airborne microbial communities during the formation and development of haze pollution process, and provide valuable data to better understand the interaction between bioaerosols and haze pollution.

The source and transport of bioaerosols in the air: A review.

Recent pandemic outbreak of the corona-virus disease 2019 (COVID-19) has raised widespread concerns about the importance of the bioaerosols. They are atmospheric aerosol particles of biological origins, mainly including bacteria, fungi, viruses, pollen, and cell debris. Bioaerosols can exert a substantial impact on ecosystems, climate change, air quality, and public health. Here, we review several relevant topics on bioaerosols, including sampling and detection techniques, characterization, effects on health and air quality, and control methods. However, very few studies have focused on the source apportionment and transport of bioaerosols. The knowledge of the sources and transport pathways of bioaerosols is essential for a comprehensive understanding of the role microorganisms play in the atmosphere and control the spread of epidemic diseases associated with them. Therefore, this review comprehensively summarizes the up to date progress on the source characteristics, source identification, and diffusion and transport process of bioaerosols. We intercompare three types of diffusion and transport models, with a special emphasis on a widely used mathematical model. This review also highlights the main factors affecting the source emission and transport process, such as biogeographic regions, land-use types, and environmental factors. Finally, this review outlines future perspectives on bioaerosols.

Mid-term Results of Coil Embolization Alone and Stent-assisted Coil Embolization for Renal Artery Aneurysms.

BACKGROUND: Coil embolization (CE) alone and stent-assisted coil embolization (SCE) are two major endovascular techniques to treat renal artery aneurysms (RAAs). This study aimed at providing safety and efficacy data of CE and SCE for RAAs. METHODS: Between August 2015 and June 2019, 40 RAA patients treated with CE or SCE were included in the retrospective study. Patients' demographics, clinical manifestations, aneurysm characteristics, treatment strategies, and follow-up results were collected and analyzed. RESULTS: There were 26 and 14 patients in the CE and SCE group, respectively. The mean aneurysm diameter was 2.5 ± 1.5 cm and 2.2 ± 0.8 cm (CE versus SCE, P = 0.52). The neck width of the aneurysm was 0.63 ± 0.37 cm and 1.07 ± 0.42 cm (CE versus SCE, P = 0.021). Technical success was achieved in 97.5% patients. No death or aneurysm rupture occurred. During the perioperative period, 12% and 7.1% patients suffered partial renal infarction (CE versus SCE, P = 0.45). The mean duration of follow-up was 8.8 ± 9.4 months and 16.1 ± 16.3 months (CE versus SCE, P = 0.158) by imaging and 20.8 ± 11.3 and 22.7 ± 16.5 months by visit/telephone (CE versus SCE, P = 0.703). During the follow-up, 17.4% patients in the CE group and 30.8% patients in the SCE group suffered partial renal infarction, while their overall renal function remained normal. In addition, there was no aneurysm recurrence, sac enlargement, or death in both groups. CONCLUSIONS: Both CE and SCE were safe and effective to treat RAAs. In addition, SCE may prevent coil migration in the wide neck aneurysm in selected patients.

Tea polyphenols inhibit the growth and virulence of ETEC K88.

Diarrhea caused by Enterotoxigenic Escherichia coli (ETEC) causes high levels of morbidity and mortality in neonatal piglets. Owing to the abuse of antibiotics and emergence of drug resistance, antibiotics are no longer considered only beneficial, but also potentially harmful drugs. Supplements that can inhibit the growth of bacteria are expected to replace antibiotics. Tea polyphenols have numerous important biological functions, including antibacterial, antiviral, antioxidative, anti-inflammatory, and antihypertensive effects. We investigated the role of tea polyphenols in ETEC K88 infection using a mouse model. Pretreating with tea polyphenols attenuated the symptoms induced by ETEC K88. Furthermore, in a cell adherence assay, tea polyphenols inhibited ETEC K88 adherence to IPEC-J2 cells. When cells were infected with ETEC K88, mRNA and protein levels of claudin-1 were significantly decreased compared with those of control cells. However, when cells were pretreated with tea polyphenols, claudin-1 mRNA and protein levels were higher than those in cells without pretreatment upon cell infection with ETEC K88. TLR2 mRNA levels were also higher following cell infection with ETEC K88 when cells were pretreated with tea polyphenols. These data revealed that tea polyphenols could increase the barrier integrity of IPEC-J2 cells by upregulating expression of claudin-1 through activation of TLR2. Tea polyphenols had beneficial effects on epithelial barrier function. Therefore, tea polyphenols could be used as a novel strategy to control and treat pig infections caused by ETEC K88.

Vertical variations in the concentration and community structure of airborne microbes in PM2.5.

With the recent rapid development of urbanization, severe air pollution events frequently occur in China. Subsequently, variations of bioaerosols during air pollution events have attracted increasing attention in recent years. However, most published studies on bioaerosols mainly focus on the characteristics of airborne bacteria and fungi at a certain height near the ground surface. The vertical variations in microbial aerosols at different heights are not well understood. In this study, PM2.5 samples at three heights (1.5 m, 100 m and 229.5 m) were collected from September 2019 to January 2020 in Xi'an, China. The samples were then analyzed by a fluorescence staining and high-throughput sequencing to explore the vertical variations in the concentration and community structure of the airborne bacteria. The results show that the microbial concentration in PM2.5 decreased with increasing height on polluted days, while there was no significant difference at different heights on non-polluted days (p > 0.05). The bacterial community structures were similar at different heights on polluted days; however, on non-polluted days, the bacterial community structure at 229.5 m was significantly different from that at the other heights. Importantly, meteorological factors had more significant effects on the bacterial community at 229.5 m than at 1.5 m and 100 m. The present results can improve the understanding of vertical distribution of bioaerosols and their diffusion process.

The effects of short-term treatment of microcystin-LR on the insulin pathway in both the HL7702 cell line and livers of mice.

Our previous work indicated exposure of Human liver cell 7702 (HL7702) cells to Microcystin-leucine-arginine (MC-LR) for 24 hours can disrupt insulin (INS) signaling by the hyperphosphorylation of specific proteins. For further exploring the time-dependent effect posed by MC-LR on this pathway, in the current study, HL7702 cells together with mice were exposed to the MC-LR with different concentrations under short-term treatment, and then, protein phosphatase 2A (PP2A) activity and expression of proteins related to INS signaling, as well as the characteristics of their action in the liver, were investigated. The results indicated, in HL7702 cells with 0.5, 1, and 6 hours of treatment by MC-LR, PP2A activity showed an obvious decrease in a time and concentration-dependent manner. While the total protein level of Akt, glycogen synthase kinase 3 (GSK-3), and glycogen synthase remained unchanged, GSK-3 and Akt phosphorylation increased significantly. In livers of mice with 1 hour of intraperitoneal injection with MC-LR, a similar change in these proteins was observed. In addition, the levels of total IRS1 and p-IRS1 at serine sites showed decreasing and increasing trends,respectively, and the hematoxylin and eosin staining showed that liver tissues of mice in the maximum-dose group exhibited obvious hepatocyte degeneration and hemorrhage. Our results further proved that short-term treatment with MC-LR can inhibit PP2A activity and disrupt INS signaling proteins' phosphorylation level, thereby interfering with the INS pathway. Our findings provide a helpful understanding of the toxic effects posed by MC-LR on the glucose metabolism of liver via interference with the INS signaling pathway.

Microcystin-LR exposure disrupts the insulin signaling pathway in C2C12 mice muscle cell line.

Microcystin-LR (MC-LR) is a widely produced monocyclic heptapeptides in eutrophication waterbodies. MC-LR can induce various toxic effects in different cells. Our previous studies have found that MC-LR exposure can disrupt insulin signaling pathway in human liver cells (HL 7702). Skeletal muscle is one of the major organs for glucose disposal and responsive to insulin. However, the effects of MC-LR on insulin signaling pathway in muscle cells have not been fully explored. By using C2C12 mice muscle cells, this study aims to investigate the toxic effects of MC-LR in muscle cells with a focus on its effects on insulin signaling pathways. It was found that MC-LR entered into cells and inhibited protein phosphatase 2A (PP2A) significantly. Furthermore, MC-LR increased phosphorylation of Ser302, Ser307, Ser612 of insulin receptor substrate 1, AKT-Ser473, GSK3α-Ser21, and S6K1-Thr389 by inhibiting the activity of PP2A. The results in this study demonstrate that exposure of MCLR can disrupt the insulin pathway in muscle cells.