Development of optical nanoprobes for molecular imaging of reactive oxygen and nitrogen species

Reactive oxygen and nitrogen species (RONS) play important roles in cell signal transduction. However, overproduction of RONS is associated with a series of pathological processes and may disrupt cellular homeostasis, causing oxidative and nitrosative stress. Accurate methods to selectively and specifically monitor RONS in living systems are required to further elucidate the biological functions of these species. Optical imaging possesses high sensitivity, high spatiotemporal resolution, and real-time imaging capability. These qualities are advantageous for the detection of RONS in living systems. This review summarizes the development of optical nanoprobes with near-infrared (NIR) fluorescent, upconversion luminescent, chemiluminescent, or photoacoustic signals for molecular imaging of RONS in living systems. In this review, we discuss the design principles and advantages of RONS-responsive activatable nanoprobes, as well as applications of these optical imaging modalities in different disease models.     

Multi-functionalized nanofibers with reactive oxygen species scavenging capability and fibrocartilage inductivity for tendon-bone integration

The presence of excessive reactive oxygen species(ROS)after injuries to the enthesis could lead to cellular oxidative damage,high inflammatory response,chronic inflammation,and limited fibrochondral induc-tivity,making tissue repair and functional recovery difficult.Here,a multifunctional silk fibroin nanofiber modified with polydopamine and kartogenin was designed and fabricated to not only effectively reduce inflammation by scavenging ROS in the early stage of the enthesis healing but also enhance fibrocarti-lage formation with fibrochondrogenic induction in the later stages.The in vitro results confirmed the antioxidant capability and the fibrochondral inductivity of the functionalized nanofibers.In vivo studies showed that the multifunctional nanofiber can significantly improve the integration of tendon-bone and accelerate the regeneration of interface tissue,resulting in an excellent biomechanical property.Thus,the incorporation of antioxidant and bio-active molecules into extracellular matrix-like biomaterials in interface tissue engineering provides an integrative approach that facilitates damaged tissue regeneration and functional recovery,thereby improving the clinical outcome of the engineered tissue.     

Non-thermal dielectric barrier discharge plasma induces angiogenesis through reactive oxygen species

Vascularization plays a key role in processes such as wound healing and tissue engineering. Non-thermal plasma, which primarily produces reactive oxygen species (ROS), has recently emerged as an efficient tool in medical applications including blood coagulation, sterilization and malignant cell apoptosis. Liquids and porcine aortic endothelial cells were treated with a non-thermal dielectric barrier discharge plasma in vitro. Plasma treatment of phosphate-buffered saline (PBS) and serum-free medium increased ROS concentration in a dose-dependent manner, with a higher concentration observed in serum-free medium compared with PBS. Species concentration inside cells peaked 1 h after treatment, followed by a decrease 3 h post treatment. Endothelial cells treated with a plasma dose of 4.2 J cm^–2 had 1.7 times more cells than untreated samples 5 days after plasma treatment. The 4.2 J cm^–2 plasma dose increased two-dimensional migration distance by 40 per cent compared with untreated control, while the number of cells that migrated through a three-dimensional collagen gel increased by 15 per cent. Tube formation was also enhanced by plasma treatment, with tube lengths in plasma-treated samples measuring 2.6 times longer than control samples. A fibroblast growth factor-2 (FGF-2) neutralizing antibody and ROS scavengers abrogated these angiogenic effects. These data indicate that plasma enhanced proliferation, migration and tube formation is due to FGF-2 release induced by plasma-produced ROS. Non-thermal plasma may be used as a potential tool for applying ROS in precise doses to enhance vascularization.     

Fluorescent approach to quantitation of reactive oxygen species in mainstream cigarette smoke

A novel approach to monitoring of mainstream smoke reactive oxygen species (ROS) has been developed and applied to the quantitation of smoke oxidants. Redox-active fluorescent probe dihydrorhodamine 6G (DHR-6G) was selected as the molecular probe because it is sensitive to typical smoke ROS. The experimental system couples an automatic cigarette smoke machine fiber-optic fluorometer for real-time monitoring of the reaction progress between cigarette smoke and DHR-6G. Quantitation was achieved based on the amount of rhodamine 6G, which is the sole product from DHR-6G oxidation. With the optimization of the trapping efficiency, we detected 391 nmol of ROS/cigarette in the mainstream CS for a standard cigarette 2R4F under standard Federal Trade Commission smoking protocol. Applying this method, we quantified the ROS of selected cigarettes and found that the cigarettes made of burley tobacco have much ( approximately 10 times) higher ROS content in the smoke than that in the tobacco made of bright tobacco. The smokeless cigarette, Eclipse, has comparable ROS with cigarettes made of bright tobacco.     

Simultaneous determination of reactive oxygen and nitrogen species in mitochondrial compartments of apoptotic HepG2 cells and PC12 cells based on microchip electrophoresis-laser-induced fluorescence

Determination of intracellular bioactive species will afford beneficial information related to cell metabolism, signal transduction, cell function, and disease treatment. In this study, the first application of a microchip electrophoresis-laser-induced fluorescence (MCE-LIF) method for concurrent determination of reactive oxygen species (ROS) and reactive nitrogen species (RNS), i.e., superoxide (O(2)(-?)) and nitric oxide (NO) in mitochondria, was developed using fluorescent probes 2-chloro-1,3-dibenzothiazolinecyclohexene (DBZTC) and 3-amino,4-aminomethyl-2',7'-difluorescein (DAF-FM), respectively. Potential interference of intracellular dehydroascorbic acid (DHA) and ascorbic acid (AA) for NO detection with DAF-FM was eliminated through oxidation of AA with the addition of ascorbate oxidase, followed by subsequent MCE separation. Fluorescent products of O(2)(-?) and NO, DBZTC oxide (DBO), and DAF-FM triazole (DAF-FMT) showed excellent baseline separation within 1 min with a running buffer of 40 mM Tris solution (pH 7.4) and a separating electric field of 500 V/cm. The levels of DBO and DAF-FMT in mitochondria isolated from normal HepG2 cells and PC12 cells were evaluated using this method. Furthermore, the changes of DBO and DAF-FMT levels in mitochondria isolated from apoptotic HepG2 cells and PC12 cells could also be detected. The current approach was proved to be simple, fast, reproducible, and efficient. Measurement of the two species with the method will be beneficial to understand ROS/RNS distinctive functions. In addition, it will provide new insights into the role that both species play in biological systems.     

Photodecomposition of 4-chlorophenol by reactive oxygen species in UV/air system

In this article, the photo-degradation of 4-chlorophenol (4-CP) under UV irradiation was studied with focus on the photodecomposition of 4-CP by reactive oxygen species (ROS). 4-CP underwent much faster and more complete degradation in UV/air system than in UV/N₂ system. In UV/air system, the addition of t-butanol, a well-known ^•OH scavenger, significantly impeded the degradation of 4-CP. In the presence of t-butanol, the tendencies for the degradation of 4-CP and the formation of intermediates in UV/air system were very similar to those in UV/N₂ system. In UV/air system, 4-CP was degraded by two pathways, direct photolysis by absorbing the photons and the oxidation via ^•OH. The contribution of direct photolysis and the oxidation via ^•OH to 4-CP decomposition were 17.2% and 82.8%, respectively based on the apparent kinetic constants. Hydrogen peroxide, which could produce ^•OH through photolysis, was formed in UV/air system. It was shown that dissolved oxygen, organic matter in excited state and hydrogen ion are all necessary for the formation of hydrogen peroxide. The formation mechanism of H₂O₂ was proposed based on experimental evidence.     

Albumin mediated reactive oxygen species scavenging and targeted delivery of methotrexate for rheumatoid arthritis therapy

Rheumatoid arthritis(RA)is a common chronic systemic autoimmune disease.Although there are a variety of treatments for RA,the substantial clinical therapies are still limited to disease-modifying anti-rheumatic drugs(DMARD),which would induce obvious side-effect in patients after long-term administration.Herein,an uncomplicated drug-induced self-assembly strategy was proposed to fabricate enzyme-loaded albumin nanomedicine.The hydrophobic drug methotrexate(MTX)could induce self-assembly of superoxide dismutase(SOD)and human serum albumin(HSA)to form HSA-SOD-MTX nanoparticle.After intravenous injection,dual-modal imaging including fluorescence imaging or single-photon emission computed tomography(SPECT)/CT imaging exhibits high accumulation of cyanine 5.5(Cy5.5)or 125l labeled HSA-SOD-MTX nanoparticles in the joints of collagen-induced arthritis(CIA)mice.Importantly,using the synergy therapy of SOD enzyme to scavenge the reactive oxygen species(ROS)and MTX to suppress inflammation,HSA-SOD-MTX nanoparticles exhibit excellent therapeutic efficiency of RA in CIA mice compared with the other groups.Micro-CT and clinical arthritis score of RA mice further demonstrate that RA symptoms of mice treated with HSA-SOD-MTX nanoparticles is significantly relived,which was further demonstrated by the histological analysis and the inflammatory factors measurement.The synergy therapy of inflammation by MTX and SOD enzyme based on HSA-SOD-MTX nanoparticles show excellent therapeutic effects of RA without inducing obvious side effects.Therefore,our strategy may further promote the highly efficient therapy of RA using SOD enzyme to scavenge the ROS and decreasing the side-effect of MTX,which may provide the reference for clinical RA treatment.     

Effect of chemically reactive species on properties of ZnO nanowires exposed to oxygen and hydrogen plasma

We present a systematic study on the effect of oxygen and hydrogen plasma-generated reactive species on the properties of ZnO nanowires. Upon exposure to oxygen plasma, the electrical conductivity of an individual ZnO nanowire decreased with substantial changes in the surface chemistry, indicating a decrease in the number of donor-like defects and an increase in the number of electron-trapping species. In contrast, an individual ZnO nanowire exposed to hydrogen plasma showed a drastic increase in conductivity up to two orders of magnitude due to the incorporated hydrogen acting as a shallow donor inside the ZnO nanowires without a sputtering process.     

Biomechanisms of nanoparticles (toxicants, antioxidants and therapeutics): electron transfer and reactive oxygen species

In recent years, nanoparticles have received increasing attention in research and technology, including a variety of practical applications. The bioactivity appears to be related to the small particle size, in addition to inherent chemical activity as electron transfer (ET) agents, generators of reactive oxygen species (ROS) with subsequent oxidative stress (OS) and as antioxidants (AOs). The mechanism of toxicity, therapeutic action and AO property is addressed based on the ET-ROS-OS approach. There are several main classes of ET functionalities, namely, quinones (or phenolic precursors), metal compounds, aromatic nitro compounds (or reduction products) and imine or iminium species. Most of the nanospecies fall within the metal category. Cell signaling is also discussed. This review is apparently the first to address the various bioactivities based on the ET-ROS-OS-AO framework.     

PEGylated zinc oxide nanoparticles induce apoptosis in pancreatic cancer cells through reactive oxygen species

In this study, the authors have successfully prepared the polyethylene glycol (PEG)‐coated zinc oxide nanoparticles (ZNPs) and studied its effect in pancreatic cancer cells. The authors have observed a nanosized particle with spherical shape. In this study, the authors have demonstrated the cytotoxic effect of ZNP and PZNP in PANC1 cells. To be specific, PZNP was more cytotoxic compared to that of ZNP in PANC1 cancer cells. The authors have further showed that apoptosis is the main mode of cytotoxic activity. It is worth noting that PEGylation of ZNP did not decrease the cell killing activity of zinc particles, whereas it further increases its anticancer effect in the pancreatic cancer cells. The authors have observed a significant upregulation of proapoptotic BAX while expression of antiapoptotic Bcl‐2 was significantly downregulated indicating the potent anticancer effect of zinc nanoparticles. Overall, PEGylation of ZNP could be an effective strategy to improve the stability, while at the same time, its anticancer activity could be enhanced for better therapeutic response.Inspec keywords: biomedical materials, drug delivery systems, tumours, toxicology, nanoparticles, cellular biophysics, drugs, nanomedicine, cancer, nanofabrication, zinc compounds, II‐VI semiconductorsOther keywords: pancreatic cancer cells, reactive oxygen species, polyethylene glycol‐coated zinc oxide nanoparticles, cytotoxic effect, cytotoxic activity, PEGylation, anticancer effect, PEGylated zinc oxide nanoparticle induce apoptosis, proapoptotic BAX upregulation, ZnO     

Development of nitroxide radicals–containing polymer for scavenging reactive oxygen species from cigarette smoke

We developed a nitroxide radicals–containing polymer (NRP), which is composed of poly(4-methylstyrene) possessing nitroxide radicals as a side chain via amine linkage, to scavenge reactive oxygen species (ROS) from cigarette smoke. In this study, the NRP was coated onto cigarette filters and its ROS-scavenging activity from streaming cigarette smoke was evaluated. The intensity of electron spin resonance signals of the NRP in the filter decreased after exposure to cigarette smoke, indicating consumption of nitroxide radicals. To evaluate the ROS-scavenging activity of the NRP-coated filter, the amount of peroxy radicals in an extract of cigarette smoke was measured using UV–visible spectrophotometry and 1,1-diphenyl-2-picrylhydrazyl (DPPH). The absorbance of DPPH at 517 nm decreased with exposure to cigarette smoke. When NRP-coated filters were used, the decrease in the absorbance of DPPH was prevented. In contrast, both poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters, which have no nitroxide radical, did not show any effect, indicating that the nitroxide radicals in the NRP scavenge the ROS in cigarette smoke. As a result, the extract of cigarette smoke passed through the NRP-coated filter has a lower cellular toxicity than smoke passed through poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters. Accordingly, NRP is a promising material for ROS scavenging from cigarette smoke.     

An antibacterial mechanism of titanium alloy based on micro-area potential difference induced reactive oxygen species

Antimicrobial material is highly desired because of the increasing demand in biomedical application to prevent from the formation of biofilm. A common strategy for enhancing the antibacterial property of a metal material is to incorporate toxic metal such as Cu and Ag. However, the reported Cu²⁺ or Ag⁺ released concentration from antibacterial alloys was much less than the reported minimum inhibitory ion concentrations(MIC), revealing the existence of an unknown alternative...     

Elevating mitochondrial reactive oxygen species by mitochondria-targeted inhibition of superoxide dismutase with a mesoporous silica nanocarrier for cancer therapy

In the intrinsic pathway of apoptosis, stresses of mitochondrial reactive oxygen species （mitoROS） might be sensed as more effective signals than those in cytosol, as mitochondria are the major sources of reactive oxygen species （ROS） and pivotal components during cell apoptosis. Mitochondrial superoxide dismutase （SOD2） takes the leading role in eliminating mitoROS, and inhibition of SOD2 might induce severe disturbances overwhelming the mitochondrial oxidative equilibrium, which would elevate the intracellular oxidative stresses and drive cells to death. Herein, we report a general strategy to kill cancer cells by targeted inhibition of SOD2 using 2-methoxyestradiol （2-ME, an inhibitor for the SOD family） via a robust mitochondria-targeted mesoporous silica nanocarrier （mtMSN）, with the expected elevation of mitoROS and activation of apoptosis in HeLa cells. Fe304@MSN was employed in the mitochondria-targeted drug delivery and selective inhibition of mitochondrial enzymes, and was shown to be stable with good biocompatibility and high loading capacity. Due to the selective inhibition of SOD2 by 2-ME/mtMSN, enhanced elevation of mitoROS （132% of that with free 2-ME） was obtained, coupled with higher efficiency in initiating cell apoptosis （395% of that with free 2-ME in 4 h）. Finally, the 2-ME/mtMSN exhibited powerful efficacy in targeted killing of HeLa cells by taking advantage of both biological recognition and magnetic guiding, causing 97.0% cell death with only 2 Dg/mL 2-ME/mtMSN, hinting at its great potential in cancer therapy through manipulation of the delicate mitochondrial oxidative balance.     

Biocompatible custom ceria nanoparticles against reactive oxygen species resolve acute inflammatory reaction after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke with a high mortality rate,for which there currently is no effective treatment.A perihematomal edema caused by an intense inflammatory reaction is more deleterious than the hematoma itself and can result in neurological deterioration and death.Ceria nanoparticles (CeNPs) are potent free radical scavengers with potential for biomedical applications.As oxidative stress plays a major role in post-ICH inflammation,we hypothesized that CeNPs might protect against ICH.To test this hypothesis,core CeNPs were synthesized using a modified reverse micelle method and covered with phospholipid-polyethylene glycol (PEG) to achieve biocompatibility.We investigated whether our custom-made biocompatible CeNPs have protective effects against ICH.The CeNPs reduced oxidative stress,hemin-induced cytotoxicity,and inflammation in vitro.In a rodent ICH model,intravenously administered CeNPs were mainly distributed in the hemorrhagic hemisphere,suggesting that they could diffuse through the damaged blood-brain barrier.Moreover,CeNPs attenuated microglia/macrophage recruitment around the hemorrhagic lesion and inflammatory protein expression.Finally,CeNP treatment reduced the brain edema by 68.4％ as compared to the control.These results reveal the great potential of CeNPs as a novel therapeutic agent for patients with ICH.     

Modulation of the activity of the NADPH oxidase system by reactive oxygen species: influence of catalase

The nicotinamide adenine dinucleotide phosphate oxidase complex (Nox) is a major source of non-mitochondrial reactive oxygen species in cells. Nox contains both membrane (Cytb(558)) and cytosolic (p40(phox), p47(phox), p67(phox) and Rac) components. Nox has been submitted to a combination of oxygen free radicals produced by irradiation and to hydrogen peroxide. Irradiation of a single component with high doses led to partial inactivation; however, the irradiation of the whole system during its assembly phase with lower doses (2-10 Gy) led either to activation (2.7 Gy) or to strong inactivation if irradiation took place during the first minute of the assembly. Incubation of the membrane fractions or of p67(phox) with H(2)O(2) led to fast inactivation. Catalase protected weakly p67(phox) from H(2)O(2). Conversely, incubation of the membrane fractions with catalase led to over-activation of the system.     

Overproduction of reactive oxygen species in end-stage renal disease patients: a potential component of hemodialysis-associated inflammation

During the past decade, hemodialysis (HD)-induced inflammation has been linked to the development of long-term morbidity in end-stage renal disease (ESRD) patients on regular renal replacement therapy. Because interleukins and anaphylatoxins produced during HD sessions are potent activators for nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, an example of an enzyme that is responsible for overproduction of reactive oxygen species (ROS), this may constitute a link between leukocyte activation and cell or organ toxicity. Oxidative stress, which results from an imbalance between oxidant production and antioxidant defense mechanisms, has been documented in ESRD patients using lipid and/or protein oxidative markers. Characterization of HD-induced oxidative stress has included identification of potential activators for NADPH oxidase. Uremia per se could prime phagocyte oxidative burst. HD, far from improving the oxidative status, results in an enhancement of ROS owing to hemoincompatibility of the dialysis system, hemoreactivity of the membrane, and trace amounts of endotoxins in the dialysate. In addition, the HD process is associated with an impairment in antioxidant mechanisms. The resulting oxidative stress has been implicated in long-term complications including anemia, amyloidosis, accelerated atherosclerosis, and malnutrition. Prevention of oxidative stress in HD might focus on improving the hemocompatibility of the dialysis system, supplementation of deficient patients with antioxidants, and modulation of NADPH oxidase by pharmacologic approaches.     

氧气透平压缩机氮气试车新方法

利用现有中压氮气管网氮气作为氧气透平压缩机的密封气和工作介质,对其进行正式开车前的试车,从而节省调试时间以确保项目顺利进行。详细介绍了氮气试车的气体流路、试车过程及试车过程中的参数。     

Hydrolase stabilization via entanglement in poly(propylene sulfide) nanoparticles: stability towards reactive oxygen species

In the advancement of green syntheses and sustainable reactions, enzymatic biocatalysis offers extremely high reaction rates and selectivity that goes far beyond the reach of chemical catalysts; however, these enzymes suffer from typical environmental constraints, e.g. operational temperature, pH and tolerance to oxidative environments. A common hydrolase enzyme, diisopropylfluorophosphatase (DFPase, EC 3.1.8.2), has demonstrated a pronounced efficacy for the hydrolysis of a variety of substrates for potential toxin remediation, but suffers from the aforementioned limitations. As a means to enhance DFPase's stability in oxidative environments, enzymatic covalent immobilization within the polymeric matrix of poly(propylene sulfide) (PPS) nanoparticles was performed. By modifying the enzyme's exposed lysine residues via thiolation, DFPase is utilized as a comonomer/crosslinker in a mild emulsion polymerization. The resultant polymeric polysulfide shell acts as a 'sacrificial barrier' by first oxidizing to polysulfoxides and polysulfones, rendering DFPase in an active state. DFPase-PPS nanoparticles thus retain activity upon exposure to as high as 50 parts per million (ppm) of hypochlorous acid (HOCl), while native DFPase is observed as inactive at 500 parts per billion (ppb). This trend is also confirmed by enzyme-generated (chloroperoxidase (CPO), EC 1.11.1.10) reactive oxygen species (ROS) including both HOCl (3 ppm) and ClO(2) (100 ppm).     

Interplay of reactive oxygen species (ROS) and tissue engineering: a review on clinical aspects of ROS-responsive biomaterials

Reactive oxygen species (ROS) refers to the reactive molecules and free radicals of oxygen generated as the by-products of aerobic respiration. Historically, ROS are known as stress markers that are linked to the response of immune cell against microbial invasion, but recent discoveries suggest their role as secondary messengers in signal transduction and cell cycle. Tissue engineering (TE) techniques have the capabilities to harness such properties of ROS for the effective regeneration of damaged tissues. TE employs stem cells and biomaterial matrix, to heal and regenerate injured tissue and organ. During regeneration, one of the constraints is the unavailability of oxygen as proper vasculature is absent at the injured site. This creates hypoxic conditions at the site of regeneration. Hence, effective response against the stresses like hypoxia spurs the regeneration process. Contrary, hyperoxic condition may increase the risk of ROS stress at the site. TE tries to overcome these limitations with the new class of biomaterials that can sense such stresses and respond accordingly. This review endeavors to explain the role of ROS in stem cell proliferation and differentiation, which is a key component in regeneration. This compilation also highlights the new class of biomaterials that can overcome the hypoxic conditions during tissue regeneration along with emphasis on the ROS-responsive biomaterials and their clinical applications. Incorporating these biomaterials in scaffolds development holds huge potential in tissue or organ regeneration and even in drug delivery.

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