- A label-free electrochemical platform for the detection of antibiotics based on cascade enzymatic amplification coupled with a split G-quadruplex DNAzyme. [Journal Article]
- AAnalyst 2019 Jul 22
- Herein, a split G-quadruplex DNAzyme as a signal reporter was integrated into an electrochemical sensing platform for the detection of antibiotics with specificity and sensitivity. To improve the sig…
Herein, a split G-quadruplex DNAzyme as a signal reporter was integrated into an electrochemical sensing platform for the detection of antibiotics with specificity and sensitivity. To improve the signal-to-noise ratio, two G-rich oligonucleotide sequences (G1 and G2) were blocked into two different hairpin probes, preventing the two segments from assembling into a spilt G-quadruplex structure. Moreover, we designed a double-arch probe, consisting of an aptamer as the recognition element and two-step enzymatic signal amplification. Concretely, the first is the Nt.BbvCI-assisted nicking cyclic reaction activated by target-aptamer binding, and the second is exonuclease III-aided cyclic amplification for generating abundant G1 and G2. The modified capture probe on the electrode was used to combine G1 and G2 to form the spilt G-quadruplex/hemin when K+ and hemin were present. This complex plays the role of DNAzyme with superior horseradish peroxidase activity in catalyzing the decomposition of H2O2. Under optimal conditions, this biosensor showed an excellent performance for sensing kanamycin with a detection limit of 83 fM for kanamycin concentrations ranging from 100 fM to 1 nM. Hence, the proposed strategy has potential as an efficient and actual platform for small molecule analysis.
- Nrf2/HO-1 signaling pathway participated in the protection of hydrogen sulfide on neuropathic pain in rats. [Journal Article]
- IIInt Immunopharmacol 2019 Jul 17; 75:105746
- Neuropathic pain is evoked by aberrant sensory processing in the peripheral or central nervous system, which is characterized by persistent pain, tactile allodynia, or hyperalgesia. Neuroinflammation…
Neuropathic pain is evoked by aberrant sensory processing in the peripheral or central nervous system, which is characterized by persistent pain, tactile allodynia, or hyperalgesia. Neuroinflammation is associated with the initiation and maintenance of persistent pain in both the peripheral and central nervous systems. Hydrogen sulfide plays important regulatory roles in different physiological and pathological conditions. Therefore, we investigated the effect of hydrogen sulfide on allodynia, hyperalgesia and cytokine release in rats with neuropathic pain and the related regulatory mechanism. Neuropathic pain was established by chronic constriction injury (CCI) of the sciatic nerve in rats. Nuclear factor erythroid-2 (NF-E2)-related factor 2 (Nrf2) siRNA, hemin, Sn-protoporphyrin (SnPP)-IX and/or NaHS were administered to rats with neuropathic pain, and the spinal cord was collected to detect the expression of Nrf2, hemeoxygenase-1 (HO-1), nuclear factor-kappa B (NF-κb) and the cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and high mobility group box (HMGB)-1 by Western blot (WB) analysis, reverse transcription polymerase chain reaction (RT-PCR), immunofluorescence or enzyme-linked immunosorbent assay (ELISA). Mechanical allodynia, thermal hyperalgesia and the number of paw lifts were measured at different time points after operation. In the present research, neuropathic pain induced Nrf2 and HO-1 expression in the microglial cells of the spinal cord; Nrf2 and HO-1 were necessary to alleviate the hyperalgesia of CCI-induced rats; NaHS mitigated the hyperalgesia and allodynia induced by the CCI operation; and NaHS mitigated the excessive release of the cytokines TNF-α, IL-1β, IL-6 and HMGB1 via the Nrf2/HO-1 pathway in the microglial cells of the spinal cord. These results indicated that NaHS exhibited antinociceptive and anti-inflammatory effects that were associated with the activation of the Nrf2/HO-1 pathway in the spinal cord of rats with neuropathic pain.
- Fluorescent Graphitic Carbon Nitride-Based Nanozymes with Peroxidase-like Activities for Ratiometric Biosensing. [Journal Article]
- ACAnal Chem 2019 Jul 18
- While breakthroughs in peroxidase-like nanozymes for bioanalysis have been made, most of current nanozyme biosensing systems were based on the single signal output. Such sensing systems could be easi…
While breakthroughs in peroxidase-like nanozymes for bioanalysis have been made, most of current nanozyme biosensing systems were based on the single signal output. Such sensing systems could be easily influenced by environmental and personal factors. We envisioned that nanozyme sensing systems with ratiometric signal outputs would provide more reliable and robust sensing performance. Herein, to construct such ratiometric sensing systems, three fluorescent graphitic carbon nitride (C3N4)-based nanozymes (i.e., C3N4-Ru, C3N4-Cu, and C3N4-hemin) with excellent peroxidase-like activities were prepared. These fluorescent nanozymes emitted a fluorescence at 438 nm when excited at 385 nm. Interestingly, when o-phenylenediamine (OPD) was catalytically oxidized to OPDox in the presence of H2O2 and nanozymes, the OPDox could not only emit an emerging fluorescence at 564 nm but quench the fluorescence at 438 nm of the nanozymes. We therefore employed the ratio of the fluorescent intensity at 564 nm and 438 nm (i.e., F564/F438) as the signal output to construct ratiometric biosensing systems. First, we used C3N4-Ru nanozyme to construct ratiometric H2O2 sensing system, which showed not only the enhanced robustness, but wider linear range and better sensitivity than most reported H2O2 sensor based on nanozymes. Second, with the assistance of glucose oxidase, glucose was detected by such ratiometric sensing systems. Third, we used three C3N4-based nanozymes to construct ratiometric sensor arrays for the detection and discrimination of five phosphates. This study provides new insights for constructing robust nanozyme biosensing systems.
- Iron-Dependent Trafficking of 5-Lipoxygenase and Impact on Human Macrophage Activation. [Journal Article]
- FIFront Immunol 2019; 10:1347
- 5-lipoxygenase (5-LOX) is a non-heme iron-containing dioxygenase expressed in immune cells that catalyzes the two initial steps in the biosynthesis of leukotrienes. It is well known that 5-LOX activa…
5-lipoxygenase (5-LOX) is a non-heme iron-containing dioxygenase expressed in immune cells that catalyzes the two initial steps in the biosynthesis of leukotrienes. It is well known that 5-LOX activation in innate immunity cells is related to different iron-associated pro-inflammatory disorders, including cancer, neurodegenerative diseases, and atherosclerosis. However, the molecular and cellular mechanism(s) underlying the interplay between iron and 5-LOX activation are largely unexplored. In this study, we investigated whether iron (in the form of Fe3+ and hemin) might modulate 5-LOX influencing its membrane binding, subcellular distribution, and functional activity. We proved by fluorescence resonance energy transfer approach that metal removal from the recombinant human 5-LOX, not only altered the catalytic activity of the enzyme, but also impaired its membrane-binding. To ascertain whether iron can modulate the subcellular distribution of 5-LOX in immune cells, we exposed THP-1 macrophages and human primary macrophages to exogenous iron. Cells exposed to increasing amounts of Fe3+ showed a redistribution (ranging from ~45 to 75%) of the cytosolic 5-LOX to the nuclear fraction. Accordingly, confocal microscopy revealed that acute exposure to extracellular Fe3+, as well as hemin, caused an overt increase in the nuclear fluorescence of 5-LOX, accompanied by a co-localization with the 5-LOX activating protein (FLAP) both in THP-1 macrophages and human macrophages. The functional relevance of iron overloading was demonstrated by a marked induction of the expression of interleukin-6 in iron-treated macrophages. Importantly, pre-treatment of cells with the iron-chelating agent deferoxamine completely abolished the hemin-dependent translocation of 5-LOX to the nuclear fraction, and significantly reverted its effect on interleukin-6 overexpression. These results suggest that exogenous iron modulates the biological activity of 5-LOX in macrophages by increasing its ability to bind to nuclear membranes, further supporting a role for iron in inflammation-based diseases where its homeostasis is altered and suggesting further evidence of risks related to iron overload.
- Augmentation of EPR Effect and Efficacy of Anticancer Nanomedicine by Carbon Monoxide Generating Agents. [Journal Article]
- PPharmaceutics 2019 Jul 16; 11(7)
- One obstacle to the successful delivery of nanodrugs into solid tumors is the heterogeneity of an enhanced permeability and retention (EPR) effect as a result of occluded or embolized tumor blood ves…
One obstacle to the successful delivery of nanodrugs into solid tumors is the heterogeneity of an enhanced permeability and retention (EPR) effect as a result of occluded or embolized tumor blood vessels. Therefore, the augmentation of the EPR effect is critical for satisfactory anticancer nanomedicine. In this study, we focused on one vascular mediator involved in the EPR effect, carbon monoxide (CO), and utilized two CO generating agents, one is an extrinsic CO donor (SMA/CORM2 micelle) and another is an inducer of endogenous CO generation via heme oxygenase-1 (HO-1) induction that is carried out using pegylated hemin. Both agents generated CO selectively in solid tumors, which resulted in an enhanced EPR effect and a two- to three-folds increased tumor accumulation of nanodrugs. An increase in drug accumulation in the normal tissue did not occur with the treatment of CO generators. In vivo imaging also clearly indicated a more intensified fluorescence of macromolecular nanoprobe in solid tumors when combined with these CO generators. Consequently, the combination of CO generators with anticancer nanodrugs resulted in an increased anticancer effect in the different transplanted solid tumor models. These findings strongly warrant the potential application of these CO generators as EPR enhancers in order to enhance tumor detection and therapy using nanodrugs.
- Enzyme Mimic Basing on Self-assembled Chitosan/DNA Hybrid Exhibits Superior Activity and Tolerance. [Journal Article]
- CChemistry 2019 Jul 17
- Nature has evolved exquisite active sites with which enzymes catalyze biotransformations with high efficiency. However, the exploitation of natural enzymes is often hampered by poor stability and nat…
Nature has evolved exquisite active sites with which enzymes catalyze biotransformations with high efficiency. However, the exploitation of natural enzymes is often hampered by poor stability and natural enzyme production and purification are costly. Supramolecular self-assembly allows one to construct biomimetic active sites, although it is challenging to produce such artificial enzymes with catalytic activity and stability that rivals those of natural enzymes. In this work, we report a modular strategy to produce horseradish peroxidase (HRP)-mimicking materials based on the assembly of chitosan with a G-quadruplex DNA (G-DNA)/hemin complex. A network-like morphology of the assembled nanomaterials was observed together with a remarkable enhancement of peroxidase activity by the chitosan and G-DNA components. The turnover rate and catalytic efficiency of the enzyme-mimicking materials reached or even surpassed those of HRP. Moreover, the catalytic complexes exhibited higher tolerability than HRP to harsh environments, such as extremely low pH or high temperature. The superior activity was attributed to: i) the formation of enzyme-like active sites, ii) the facilitated adsorption of the substrates to hemin by spatially distributed chitosan and G-DNA components and iii) facile access of the substrates to the exposed catalytic center. Our work provides a simple and affordable avenue to produce highly active and robust enzyme-mimicking catalytic nanomaterials.
- Acute hepatic porphyrias: Current diagnosis & management. [Review]
- MGMol Genet Metab 2019 Jul 05
- Each of the four acute hepatic porphyrias is due to mutation of an enzyme in the heme biosynthetic pathway. The accumulation of pathway intermediates that occur most notably when these diseases are a…
Each of the four acute hepatic porphyrias is due to mutation of an enzyme in the heme biosynthetic pathway. The accumulation of pathway intermediates that occur most notably when these diseases are active is the basis for screening and establishing a biochemical diagnosis of these rare disorders. Measurement of enzyme activities and especially DNA testing also are important for diagnosis. Suspicion of the diagnosis and specific testing, particularly measurement of urinary porphobilinogen, are often delayed because the symptoms are nonspecific, even when severe. Urinary porphyrins are also measured, but their elevation is much less specific. If porphobilinogen is elevated, second line testing will establish the type of acute porphyria. DNA testing identifies the familial mutation and enables screening of family members. Management includes removal of triggering factors whenever possible. Intravenous hemin is the most effective treatment for acute attacks. Carbohydrate loading is sometimes used for mild attacks. Cyclic attacks, if frequent, can be prevented by a GnRH analogue. Frequent noncyclic attacks are sometime preventable by scheduled (e.g. weekly) hemin infusions. Long term complications may include chronic pain, renal impairment and liver cancer. Other treatments, including RNA interference, are under development.
- Metabolic Profiling and Cold-Starvation Stress Response of Oxygen-Tolerant Lactobacillus gasseri Strains Cultured in Batch Bioreactor. [Journal Article]
- MMicroorganisms 2019 Jul 15; 7(7)
- Phenotypic and genotypic evidence indicates that many LAB strains can grow in presence of oxygen and can shift from fermentative to aerobic and/or respiratory metabolism. The aerobic and respiratory …
Phenotypic and genotypic evidence indicates that many LAB strains can grow in presence of oxygen and can shift from fermentative to aerobic and/or respiratory metabolism. The aerobic and respiratory growth of several LAB species have been studied, allowing the selection of strains showing improved biomass production, long-term survival, and resistance under oxygen and stress conditions. The aim of this work was to observe the adaptation of two Lactobacillus gasseri strains, described in a previous work, to aerobic (air injection) and respiratory (air injection plus hemin and menaquionone) conditions obtained in a batch bioreactor. One strain showed the higher biomass production and oxygen consumption as well as the lower acidification in respiratory condition. Instead, the other one grew better in aerobic condition, even though the higher resistance to cold-starvation stress was registered in respiratory condition. In silico analysis revealed notable differences between AL3 and AL5 genomes and that of the type strain. This work contributes to understanding the adaptation response of lactobacilli to aerobic and respiratory metabolism. We demonstrated that the supposed activation of respiratory metabolism may provide several modifications to cell physiology. These features may be relevant in some technological and health-promoting applications, including starter and probiotic formulations.
- Activation of TrkB/Akt signaling by a TrkB receptor agonist improves long-term histological and functional outcomes in experimental intracerebral hemorrhage. [Journal Article]
- JBJ Biomed Sci 2019 Jul 15; 26(1):53
- CONCLUSIONS: Our findings demonstrate that the activation of TrkB signaling by 7,8-DHF protects against ICH via the Akt, but not the Erk, pathway. These data provide new insights into the role of TrkB signaling deficit in the pathophysiology of ICH and highlight TrkB/Akt as possible therapeutic targets in this disease.
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- Electrochemical sandwich aptasensor for the carcinoembryonic antigen using graphene quantum dots, gold nanoparticles and nitrogen doped graphene modified electrode and exploiting the peroxidase-mimicking activity of a G-quadruplex DNAzyme. [Journal Article]
- MAMikrochim Acta 2019 Jul 13; 186(8):530
- A sandwich-type electrochemical aptasensor has been constructed and applied for sensitive and selective detection of the carcinoembryonic antigen (CEA). The surface of a glassy carbon electrode (GCE)…
A sandwich-type electrochemical aptasensor has been constructed and applied for sensitive and selective detection of the carcinoembryonic antigen (CEA). The surface of a glassy carbon electrode (GCE) was first modified with nitrogen-doped graphene and then gold nanoparticles and graphene quantum dots electrodeposited on it to obtain an architecture of type GQD/AuNP/NG/GCE. In the next step, the CEA-binding aptamer was immobilized on the modified GCE. Hemin intercalates in the amino-modified hemin aptamer to form a hemin-G-quadruplex (hemin-G4) DNAzyme. The amino modified CEA aptamer II is connected to hemin-G4 by glutaraldehyde (GA) as a linker to produce CEAaptamerII/GA/hemin-G4 (=ApII/GA/DNAzyme). Through a sandwich mode, the ApII/GA/DNAzyme bioconjugates are captured on the modified GCE. Subsequently, the hemin-G4 acts as peroxidase-mimicking DNAzyme and rapidly catalyzes the electroreduction of hydrogen peroxide. The quantitative determination of CEA was achieved by differential pulse voltammetry, best at a working potential of around -0.27 V vs. Ag/AgCl. Under optimized conditions, the assay has a linear response in the 10.0 fg mL-1 to 200.0 ng mL-1 CEA concentration range and a lower detection limit of 3.2 fg mL-1. Graphical abstract Schematic presentation of a sandwich-type electrochemical aptasensor based on nitrogen doped graphene (NG), gold nanoparticles (AuNPs) and graphene quantum dots (GQDs) modified glassy carbon electrode, and the hemin-G4 DNAzyme for femtomolar detection of the carcinoembryonic antigen.