视网膜氧化2014-Phoenix Micron III

Dynamic,in vivo,real-time detection of retinal oxidative status in a model of elevated intraocular pressure using a novel,reversibly responsive,pro?uorescent nitroxide probe

Cassie L.Rayner a,Glen A.Gole b,Steven E.Bottle c,Nigel L.Barnett a,d,e,*

a Queensland Eye Institute,South Brisbane,Queensland,Australia

b Department of Paediatrics&Child Health,University of Queensland,Brisbane,Queensland,Australia

c ARC Centre of Excellence for Free Radical Chemistry School of Physical an

d Chemical Sciences,Queensland University of Technology,Brisbane,Queensland, Australia

d Th

e University o

f Queensland,UQ Centre for Clinical Research,Herston,Queensland,Australia

e School o

f Biomedical Sciences,Queensland University of Technology,Brisbane,Queensland,Australia

a r t i c l e i n f o

Article history:

Received21August2014

Received in revised form

15October2014

Accepted in revised form16October2014 Available online25October2014

Keywords:

Oxidative stress

Retina

Fluorescent probe

Nitroxide

Reactive oxygen species

Ischemia

Reperfusion a b s t r a c t

Changes to the redox status of biological systems have been implicated in the pathogenesis of a wide variety of disorders including cancer,Ischemia-reperfusion(I/R)injury and neurodegeneration.In times of metabolic stress e.g.ischaemia/reperfusion,reactive oxygen species(ROS)production overwhelms the intrinsic antioxidant capacity of the cell,damaging vital cellular components.The ability to quantify ROS changes in vivo,is therefore essential to understanding their biological role.Here we evaluate the suitability of a novel reversible pro?uorescent probe containing a redox-sensitive nitroxide moiety (methyl ester tetraethylrhodamine nitroxide,ME-TRN),as an in vivo,real-time reporter of retinal oxidative status.The reversible nature of the probe's response offers the unique advantage of being able to monitor redox changes in both oxidizing and reducing directions in real time.After intravitreal administration of the ME-TRN probe,we induced ROS production in rat retina using an established model of complete,acute retinal ischaemia followed by reperfusion.After restoration of blood?ow, retinas were imaged using a Micron III rodent fundus?uorescence imaging system,to quantify the redox-response of the probe.Fluorescent intensity declined during the?rst60min of reperfusion.The ROS-induced change in probe?uorescence was ameliorated with the retinal antioxidant,lutein.Fluo-rescence intensity in non-Ischemia eyes did not change signi?cantly.This new probe and imaging technology provide a reversible and real-time response to oxidative changes and may allow the in vivo testing of antioxidant therapies of potential bene?t to a range of diseases linked to oxidative stress.

?2014Elsevier Ltd.All rights reserved.

1.Introduction

The accumulation of free radicals(reactive oxygen species,ROS), has been implicated in numerous neurodegenerative diseases, including Parkinson's disease(Ray et al.,2014),Alzheimer's disease (Aliev et al.,2013),cardiac diseases(Schwarz et al.,2014)and the major degenerative visual diseases such as glaucoma(Almasieh et al.,2012;Chrysostomou et al.,2013;Yuki et al.,2011),diabetic retinopathy(Wilkinson-Berka et al.,2013)and age-related macular degeneration(AMD)(Seo et al.,2012).Neurodegeneration is de?ned by the progressive loss of speci?c neuronal cell pop-ulations,with extensive evidence verifying oxidative stress a contributing factor to disease pathogenesis(Barnham et al.,2004; Scherz-Shouval and Elazar,2011).ROS are natural by-products of cellular metabolism essential in cell signalling and homoeostasis, however when cellular ROS production overwhelms the intrinsic antioxidant capacity,they become extremely damaging to vital cellular components which can lead to irreversible changes and cell death(Tezel,2006).In response to this imbalance in the cellular redox environment,i.e.oxidative stress,cells respond by activating

Abbreviations:DMSO,Dimethyl sulfoxide;ERG,Electroretinogram;GFAP,Glial ?brillary acidic protein;IBA-1,Ionized calcium binding adaptor molecule1;IOP, Intraocular pressure;I/R,Ischaemia-reperfusion;ME-TRN,Methyl ester tetrae-thylrhodamine nitroxide;OPs,Oscillatory potentials;PFN,Pro?uorescent nitro-xides;RGC,Retinal ganglion cell;ROS,Reactive oxygen species;AMD,Age-related macular degeneration.

*Corresponding author.Queensland Eye Institute,140Melbourne St,South Brisbane,Queensland4101,Australia.

E-mail address:nigel.barnett@https://www.wendangku.net/doc/a01952276.html,.au(N.L.

Barnett).Contents lists available at ScienceDirect

Experimental Eye Research jo urn al homepag e:https://www.wendangku.net/doc/a01952276.html,/locate/ye

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https://www.wendangku.net/doc/a01952276.html,/10.1016/j.exer.2014.10.013

0014-4835/?2014Elsevier Ltd.All rights reserved.

Experimental Eye Research129(2014)48e56

various defence mechanisms(Scherz-Shouval and Elazar,2007) such as up-regulation of antioxidants and/or the removal of damaged proteins and organelles by autophagy;these assist cells in restoring homoeostasis(Hamanaka and Chandel,2010;Kif?n et al., 2006;Lemasters,2005;Scherz-Shouval and Elazar,2007).Accu-mulating data has implicated mitochondria as the main source for regulation of autophagy by ROS(Azad et al.,2009;Chen et al.,2007; Hamanaka and Chandel,2010;Scherz-Shouval et al.,2007). Signi?cantly,whilst retinal photoreceptors have the highest density of mitochondria of all central nervous system neurons(Kageyama and Wong-Riley,1984),retinal ganglion cells are also particularly susceptible to mitochondrial dysfunction,which has critical importance in the initiation of glaucoma and subsequent vision loss (Chrysostomou et al.,2013;Osborne and del Olmo-Aguado,2013).

Retinal Ischemia-reperfusion(I/R)injury induced by transient elevation of intraocular pressure(IOP)in animal models,results in necrosis and apoptosis of cells in both the ganglion cell layer and inner nuclear layer(Hughes,1991;Kuroiwa et al.,1998;Li et al., 2009;Oharazawa et al.,2010).Excessive elevation of IOP impairs blood?ow dynamics in the retina and the optic nerve head, reducing the delivery of energy and nutrients required for cell survival,thus rendering them susceptible to additional insults (Osborne,2008).Extensive evidence for this pathological mecha-nism has lead to the vascular theory of glaucoma(Arend et al., 2004;Chung et al.,1999;Hall et al.,2001;Mitchell et al.,2005). ROS production is a complex,dynamic phenomenon occurring during and after a period of cellular energy deprivation,e.g.acute I/ R injury,predisposing the retina to oxidative damage(Abramov et al.,2007;Li et al.,2009).The ability to detect and quantify ROS in vivo and in real-time,is therefore essential to understanding their biological roles.

Fluorescent detection or imaging with redox-responsive probes is a potentially powerful approach because of its merits of high sensitivity,easy visualization,simple operation,high spatial reso-lution in microscopic imaging techniques and most importantly in vivo application(Fernandez-Suarez and Ting,2008;Wen-Xue and Xu,2012;Xu et al.,2013).Previously,?uorescent techniques largely involved the irreversible reaction of a non-?uorescent probe molecule with a radical of interest to produce a detectable?uo-rescent product(Halliwell and Whiteman,2004;Morrow et al., 2010;Wardman,2007).Such‘one-way’detection methodologies can have limitations,as they are not able to respond to dynamic changes to the cellular redox environment.With the chemistry of the probe response being irreversible,such techniques therefore cannot be used to identify the potential therapeutic bene?t of antioxidant intervention following the induction of a pro-oxidant stress.This ultimately prompted the development of reversible ‘two-way’probes,with stable nitroxide radicals having signi?cant potential in this regard(Morrow et al.,2010).

Nitroxides have previously been employed to probe various biophysical and biochemical processes involving oxidative stress (Ahn et al.,2012;Hirosawa et al.,2012;Mitchell et al.,2001;Wang et al.,2013),due to their high scavenger ability,reactivity to ROS (Ahn et al.,2012)and on the basis of their metabolism to reduced hydroxylamine(Morrow et al.,2010).Various cellular redox pro-cesses are capable of mediating the conversion between the reduced hydroxylamine and the oxidized nitroxide species and hence the ratio of these two states is indicative of the overall “reducing capacity”,or redox environment,of the cell(Belkin et al., 1987;Morrow et al.,2010;Swartz,1987,1990).Covalently linking a nitroxide moiety to a?uorescent structure possessing excitation and emission pro?les of biological relevance(Morrow et al.,2010), e.g.rhodamine,ef?ciently quenches the excited state that leads to ?uorescence(Ahn et al.,2012;Blough and Simpson,1988;Green et al.,1990).The removal of the nitroxide free radical through a one-electron reduction to the non-radical hydroxylamine,removes this quenching effect resulting in the restoration of the typical ?uorescence of the?uorophore(Blough and Simpson,1988).As the response of the nitroxide is reversible and is re?ected in changes in the?uorescence emission,this enables a unique investigative tool with the potential to provide real-time insight into diseases of oxidative stress in the eye(Morrow et al.,2010).These probes have been described as pro?uorescent nitroxides(PFN)as the?uores-cence is switched on through metabolic or chemical processes akin to prodrugs.

We have developed a novel,reversible,PFN probe(methyl ester tetraethylrhodamine nitroxide;ME-TRN),based on the rhodamine class of?uorescent dyes.We chose this structure due to its excel-lent?uorescent quantum yields,high solubility and stability in water and most importantly for its selective accumulation by mitochondria in living cells(Johnson et al.,1980;Morrow et al., 2010).Here we evaluate the suitability of an ME-TRN probe as an in vivo,real-time reporter of retinal oxidative status.The utility of PFN probes to quantify oxidative status in isolated cells by?ow cytometry and?uorescence imaging has been previously demon-strated(Ahn et al.,2012;Morrow et al.,2010)and to translate these ?ndings to the retina,in vivo,we used an established model of complete,acute retinal ischaemia followed by reperfusion.The generation of ROS following the Ischemia insult provides a known, in vivo,pro-oxidant condition,upon which we based our initial investigations.The known antioxidant and free radical scavenger, lutein,has previously been shown to protect macula and photore-ceptors from phototoxicity and oxidative injury(Alves-Rodrigues and Shao,2004;Chucair et al.,2007;Li et al.,2009)and more recently the inner retinal neurons from Ischemia-reperfusion challenge,possibly by reducing oxidative stress(Dilsiz et al.,2006; Li et al.,2009).Based on these?ndings,lutein is considered an effective antioxidant.Accordingly,we used lutein to verify the ?uorescent redox response of our probe.A validated technique for the measurement of retinal oxidative status in vivo could have a major impact on the ability to assess other putative neuroprotective antioxidants for the treatment of glaucoma and other neurode-generative diseases.

2.Materials and methods

2.1.Animals and treatments

Albino Sprague e Dawley rats(female,~250g)obtained from the Animal Resources Centre(Canning Vale,WA,Australia)at8weeks of age,were housed at Herston Medical Research Centre Animal Facility(Royal Brisbane&Women's Hospital,Australia).Animals were maintained in temperature and humidity controlled rooms (~37 C and60e70%respectively),with food and water available ad libitum.A12:12h light/dark cycle(lights on at7a.m.)was used, with illumination provided by overhead?uorescent white lights.

Animals were divided into four treatment groups for I/R studies: (i)control/non-Ischemia(n?9),(ii)acute I/R injury(n?6),(iii) lutein(n?7)or(iv)acute I/R injurytlutein(n?6).Each group received an intravitreal injection of ME-TRN probe,prior to I/R or non-Ischemia treatment.Lutein or vehicle10%dimethyl sulfoxide (DMSO)was administered by intraperitoneal injection1h prior to I/R(see preparation below).

Animals prepared for ERG and immunohistochemistry(n?3) were administered ME-TRN probe to one eye with the contralateral eye serving as a control for comparison purposes.Control eyes received a2m l vehicle injection of10%DMSO in injectable saline.

Experiments were conducted in accordance with the‘Animal Care and Protection Act(QLD)2001’,‘The Australian Code of Prac-tice for the Care and Use of Animals for Scienti?c Purposes’and the

C.L.Rayner et al./Experimental Eye Research129(2014)48e5649

ARVO statement for the Use of Animals in Ophthalmic and Vision Research.

2.2.ME-TRN administration

Animals were anaesthetized by intraperitoneal injection(i.p.)of 75mg/kg ketamine and15mg/kg xylazine.Pupils were dilated with1%tropicamide and2.5%phenylepherine(Bausch and Lomb, Tampa,FL),and corneas anaesthetized with0.5%tetracaine hy-drochloride(Chauvin Pharmaceuticals,Kingston-Upon-Thames, UK).ME-TRN(2m l of5?10à5M in10%DMSO/injectable water) was injected into the vitreous of both eyes using a10m L Hamilton syringe coupled to a26gauge needle,to give a?nal concentration of2m M.Intravitreal injections were made posterior to the superior limbus at a45 angle,preventing the probe from being injected into the lens.

The probe was permitted to disperse throughout the vitreous and accumulate in the retina for30min prior to recording pre-Ischemia retinal images using a Micron III rodent fundus imaging system(Phoenix Research Labs,Pleasanton,CA,USA)equipped with rhodamine?lters(Ex556/Em590nm).Pre-Ischemia fundus images provided base line intensity measures for comparison of ME-TRN?uorescent signal change induced by superoxide produc-tion during reperfusion and for the potential ameliorative effect of antioxidant intervention.Data are expressed as?uorescence in-tensity as a percentage of pre-insult values.Fluorescent intensity was subsequently measured5,10,15,30,45and60min post Ischemia insult during the reperfusion phase.

To ensure similar fundus images were captured pre-and post I/R injury,optic nerve and major retinal blood vessel locations were clearly indicated and pre-Ischemia camera and animal stage posi-tioning were?xed;animals were simply lifted away from the Micron III to allow correct repositioning following treatment.Bright ?eld images(consistent illumination settings)were captured at each time point to verify fundus location prior to capturing?uo-rescent images.For each experimental animal,consistent excitation illumination levels and gain settings were used to acquire the ?uorescent intensity images and were maintained for each image captured throughout the treatment period.

2.3.Image analysis

Colour?uorescent fundus images were imported into Image J (National Institutes of Health,Bethesda,MD,USA)and converted to 8-bit greyscale.Average pixel intensity across the isolated circular whole fundus image was calculated to provide?uorescence in-tensity values for each time point.To account for possible vari-ability of absolute fundus?uorescence levels between animals due to probe diffusion or other confounding factors,data are presented as the change in?uorescent intensity at each time point during reperfusion as a percentage of the corresponding pre-ischaemia value(mean±SEM).

2.4.Antioxidant preparation

Lutein(0.05mg/ml)was prepared in injectable saline contain-ing10%DMSO and administered(0.2mg/kg i.p.)1h prior to I/R insult(Li et al.,2009).

2.5.Evaluating ME-TRN toxicity on retinal tissue using electroretinography(ERG)

Full-?eld ERGs were recorded as previously described(Moxon-Lester et al.,2009)1day(n?3)and8days(n?3)following ME-TRN administration to examine potential toxicity of the probe to the retina.ME-TRN probe was injected into the vitreous(as above)of the left eye,with the contralateral eye serving as the control.Brie?y,rats were dark-adapted overnight and prepared for recording under dim red light using LED illumination (l max?650nm).After anaesthesia and mydriasis,reference elec-trodes were placed on each ear and a grounding electrode posi-tioned subcutaneously on the back.A platinum wire recording electrode was positioned on each cornea,which was kept moist with GenTeal gel(Novartis Pharmaceuticals,NSW,Australia).Body temperature was maintained at37 C with an electric animal heating blanket.Rats were then placed in a custom-designed ganzfeld and subjected to the ERG?ash stimuli.ERGs were recor-ded simultaneously from both eyes.

Scotopic responses recorded at1.2log cd s mà2were elicited with a photographic?ash unit(Metz mecablitz60CT4,Zirndorf, Germany).An average of2e3?ashes were recorded with an interstimulus interval of300s to allow complete recovery of b-wave amplitudes.Responses were ampli?ed and recorded with a bioampli?er/analogue-to-digital converter(Powerlab/4ST,ADIn-struments,Castle Hill,Australia),band-pass-?ltered between0.3 and1000Hz,and digitized at4kHz.

2.6.Acute retinal ischaemia by elevation of IOP

Unilateral retinal ischaemia was induced as previously described(Holcombe et al.,2008;Moxon-Lester et al.,2009). Brie?y,anaesthetized animals were immobilized by resting the front teeth over a horizontal stabilizing bar and securing the skull with adjustable rods inserted in the bony external ear canals.The anterior chamber was cannulated with a30-gauge needle attached to a reservoir containing0.9%NaCl.A micromanipulator was used to insert the needle into the anterior chamber parallel to the iris plane at the12o'clock position.Intraocular pressure was increased to120mmHg by elevation of the reservoir to163cm.Ocular ischaemia was con?rmed by the blanching of the iris and inter-ruption of the retinal circulation.Leakage from the initial ME-TRN injection site was rarely seen,however if it transpired,animals were immediately removed from the study as complete ischaemia could not be veri?ed.After60min of elevated IOP,removal of the cannula allowed reperfusion,generating superoxide radicals upon restoration of blood?ow.During reperfusion,retinal?uorescence generated by the ME-TRN probe was imaged at5,10,15,30,45and 60min.Corneal hydration was maintained throughout.

2.7.Evaluating retinal damage using immunohistochemistry

Rats were euthanized with Lethabarb(200mg/kg i.p.,Virbac, NSW,Australia)8days following ME-TRN administration and I/R. Eyes were enucleated and?xed in10%neutral buffered formalin for 2h at room temperature.Posterior eye cups were cryoprotected with30%sucrose before mounting and freezing in OCT(Tissue Tek, ProSciTech,QLD,Australia).Transverse sections(10m m)were cut using a cryostat and maintained atà20 C until required for im-munostaining,using standard methods.Slides were incubated overnight at room temperature with polyclonal rabbit anti-Glial Fibrillary Acidic Protein(GFAP;1:1000,DakoCytomation, Glostrup,Denmark),or polyclonal rabbit anti-Ionized Calcium Binding Adaptor molecule1(IBA-1;1:2000,Wako,Osaka,Japan). Immunolabelling was visualized with Fluorolink Cy2labelled goat-anti-rabbit IgG(Amersham BioSciences,Buckinghamshire,UK) incubated for90min at room temperature.Images were viewed with an Olympus,BX41TF microscope(Tokyo,Japan)equipped with epi?uorescence and captured with an Olympus DP70camera. Images were imported into Adobe Photoshop CS5for minor editing of contrast and sharpness.

C.L.Rayner et al./Experimental Eye Research129(2014)48e56 50

2.8.Data analysis

ERG and?uorescent intensity responses are expressed as the mean±SEM.Statistical comparisons were made using a non-parametric Wilcoxon matched-pairs signed rank test for ERGs.

Following con?rmation with a D'Agostino-Pearson omnibus test that the?uorescence intensity data from each treatment group were normally distributed,the data were analysed and compared with a linear model using R software(The R Foundation for Sta-tistical Computing).P0.05was considered statistically signi?cant.

3.Results

3.1.ME-TRN uptake in rat retina

For the ME-TRN probe to be considered a suitable tool for the real-time measurement of retinal oxidative status in vivo,uptake into retinal cells is necessary.Fig.1shows a transverse section of rat retina con?rming that the ME-TRN probe is selectively accumulated by retinal neurons following intravitreal administration.These data con?rm that the observed changes in fundus?uorescence repre-sent the response of retinal cells to changes in their cellular environment.

3.2.ME-TRN administration and retinal function

The ERG,commonly used to assess the functional integrity of the retina,allows for early detection and monitoring of adverse drug effects on the visual pathways.The a-wave is the response gener-ated by photoreceptors(Penn and Hagins,1969)and the b-wave is predominantly generated by the depolarization of the ON bipolar cells(Bush and Sieving,1996;Hood and Birch,1996;Robson and Frishman,1995,1998;Sieving et al.,1994).The oscillatory poten-tials(OPs)arise from activity in the inner retina,including a major contribution from amacrine cells(Wachtmeister and Dowling, 1978).Prior to employing and evaluating our ME-TRN probe as a real-time reporter of retinal oxidative status in vivo,we initially examined its‘short and long term’toxicity to retinal tissues and their function.

ERG responses were recorded from ME-TRN and vehicle treated eyes at1day(short term)and8days(long term)post adminis-tration(Fig.2).Vehicle and ME-TRN treated eyes showed no sig-ni?cant difference in a-wave amplitude(1day:345±45m V and 400±77m V respectively;p?0.75,and8days:408±36m V and 475±84m V respectively;p?0.50)or b-wave amplitude(1day: 948±131m V and1033±150m V respectively;p?0.75,and8days: 975±82m V and1073±128m V respectively;p?0.75)(Fig.2B). Similarly,neither a-wave nor b-wave implicit times were affected by ME-TRN injection(a-wave e1day:7.25±0.29ms and 7.17±0.22ms,p!0.99;8days:7.67±0.30ms and7.58±0.08ms, p!0.99;b-wave e1day:57.08±7.83ms and55.67±7.41ms, p?0.50;8days:46.00±0.76ms and50.42±3.36ms,p?0.25,for control and ME-TRN treated eyes respectively).No signi?cant change in OP peak amplitude was observed(1day:69±11m V and 72±12m V,p!0.99;8days:61±10m V and63±10m V,p?0.99,for control and ME-TRN treated eyes respectively).These data suggest that the ME-TRN probe has no detrimental effect on retinal function and can be used at concentrations described.

3.3.Immunohistochemistry

To investigate possible toxic effects of the ME-TRN probe on the retina,we analysed glial cell activation as the hallmark of reactive gliosis and neuroin?ammation with GFAP(macroglia)and IBA-1 (microglia/macrophages)staining(Fig.3).

In the healthy retina,GFAP is the main intermediate?lament protein in astrocytes,and has limited or no expression in Müller cells.Eight days after the intravitreal injection of ME-TRN,GFAP immunoreactivity was still restricted to the astrocytes present in the nerve?bre layer.As reported previously(Larsen and Osborne, 1996),an acute I/R injury induced a drastic upregulation in GFAP immunoreactivity,signi?cantly enhancing GFAP distribution to glial processes from the inner limiting membrane to the outer retina associated with activated Müller cells.

In response to various stimuli,microglia transform into acti-vated forms that can be distinguished by their morphology and antigenicity(Streit et al.,1988).When activated,the morphology

of

Fig.1.Transverse frozen section of rat retina showing accumulation and?uorescence

of ME-TRN probe in neurons(arrows)60min after a single intravitreal injection

(2m M).Brightest?uorescence seen in the outer nuclear layer(ONL)with weaker

?uorescence displayed by cells of the inner nuclear layer(INL)and ganglion cells;IPL,

inner plexiform

layer.

Fig.2.ERG analysis of vehicle control and ME-TRN injected eyes,1and8days post

treatment(n?3,mean±SEM).(A)Representative traces of the scotopic ERG wave-

forms recorded with a stimulus of1.2log cd s mà2showing no apparent change in a-

wave,b-wave or oscillatory potential amplitude or peak latency.(B)Quanti?cation of

a-and b-wave amplitudes con?rming no signi?cant effect of ME-TRN(2m M)injection

upon retinal function.

C.L.Rayner et al./Experimental Eye Research129(2014)48e5651

microglia include a rounded nucleus,abundant cytoplasm and short processes (Ito et al.,1998).IBA-1labelled microglia (Fig.3)in post I/R retina exhibit a morphology indicative of activation.However,no evidence of microglial activation could be seen in ME-TRN treated retinas,which were qualitatively similar to control retinas.

3.4.Quanti ?cation of ?uorescence intensity following I/R injury The reperfusion phase following an acute Ischemia insult gen-erates ROS that become highly damaging to cellular components when ROS overwhelms the cell's intrinsic antioxidant capacity.The complete acute I/R rat model therefore provided a known,in vivo ,pro-oxidant condition,upon which we based our investigations.The initial assessment of ME-TRN ?uorescent intensity in non-Ischemia control eyes,demonstrated that the probe's ?uorescence in the retina was relatively stable over a 120min treatment period (60min of sham ischaemia plus 60min imaging during sham reperfusion)(Fig.4).Fig.5shows that the production of super-oxide upon restoration of blood ?ow following the Ischemia insult resulted in a signi ?cant (F (5,30)?2.864,p ?0.031)decrease in fundus ?uorescence intensity over the 60min of reperfusion (white triangles)when compared to the non-Ischemia,control group (white circles),with signi ?cant reductions seen at 10,15,

30,

Fig.3.GFAP and IBA-1immunohistochemistry of rat retinas 8days after the intravitreal injection of ME-TRN (2m M).No differences in labelling were apparent between control and ME-TRN treated retinas.GFAP immunoreactivity was restricted to the astrocytes whilst IBA-1positive microglia displayed the resting rami ?ed morphology.In contrast,an ischaemic insult followed by 8days of reperfusion resulted in a signi ?cant upregulation in GFAP immunoreactivity associated with activated Müller cells.I/R also resulted in the activation of microglia (IBA-1),which displayed a rounded nucleus,abundant cytoplasm and shorter processes.Higher magni ?cation insets show microglia nuclei in each condition of

activation.

Fig.4.In vivo fundus imaging showing the time-course of ME-TRN ?uorescence (556/590nm)in the rat eye during reperfusion following an acute ischaemic insult,and the effect of the antioxidant lutein (0.2mg/kg).Fundus ?uorescence was stable in non-ischaemic retinas throughout the 60min ‘reperfusion ’period (top rows).In contrast,reactive oxygen species generated during the reperfusion phase after acute ischaemia resulted in a marked,time-dependent,decrease in probe ?uorescence (third row).Pre-ischaemic antioxidant treatment ameliorated the I/R-induced decrease in retinal ?uorescence (bottom row).

C.L.Rayner et al./Experimental Eye Research 129(2014)48e 56

52

45and 60min reperfusion;(72.17±6.47%vs 84.50±4.18%at 5min reperfusion vs pre-ischaemia;p ?0.0577,63.33±4.09%vs 79.50± 2.91%at 10min;p ?0.0075,60.33± 4.42%vs 76.88± 4.84%at 15min;p ?0.0102,60.67± 4.79%vs 74.75± 3.86%at 30min;p ?0.0099,52.20± 6.11%vs 72.50± 4.35%at 45min;p ?0.004,and 47.17± 5.59%vs 68.71±5.42%at 60min;p ?0.0013,respectively).The absence of reducing equivalents and the presence of oxygen resulted in the equilibrium between the oxidized nitroxide molecule and the reduced hydroxylamine being pushed towards the more oxidized form of the species (Morrow et al.,2010).This oxidized form is highly unstable and rapidly converts back to the non-?uorescent nitroxide radical state,resulting in the decrease in ?uorescence we observed within this treatment group.

In non-Ischemia eyes,the intraperitoneal administration of the antioxidant lutein had no signi ?cant effect on ME-TRN retinal ?uorescence throughout the treatment period (Fig.5,black circles)when compared with the non-Ischemia control group (F (5,36)?1.354,p ?0.245).This con ?rmed that any effects seen within the I/R tlutein treatment group were the result of the antioxidative properties of lutein reducing overall oxidative stress levels.Antioxidant intervention (black triangles)successfully ameliorated the decrease in retinal ?uorescence induced by I/R injury (F (5,30)?5.706,p ?0.001),with signi ?cantly increased ?uorescence observed at 5,10and 15min into the reperfusion phase;(72.17± 6.47%vs 90.50± 5.86%at 5min;p ?0.026,63.33± 4.09%vs 86.33±7.61%at 10min;p ?0.0047,60.33± 4.42%vs 83.71± 2.25%at 15min;p ?0.0044,60.67± 4.79%vs 71.00± 3.97%at 30min;p ?0.1573,52.20± 6.11%vs 64.00± 5.56%at 45min;p ?0.1691,and 47.17±5.59%vs 57.83±1.83%at 60min;p ?0.2783for I/R and I/R tlutein treatment groups respectively).4.Discussion

Pro-oxidants are recognized as having a crucial role in various biological processes including the regulation of normal

physiological processes (Morrow et al.,2010;Nathan,2003),how-ever in excess,can lead to an imbalance in the redox environment and lead to a variety of disorders including cancer,I/R injury,and neurodegeneration (Dirani et al.,2011;Hess and Manson,1984;Lin and Beal,2006;Liu et al.,2007;Morrow et al.,2010;Tezel,2006;Yapici et al.,2011).Techniques capable of quantifying and visual-ising the changes to the cellular redox environment of biological systems as a result of pro-oxidant or antioxidant processes are therefore crucial for understanding the mechanistic links between free radical chemistry and disease outcomes (Morrow et al.,2010).The most effective way to de ?ne this link is with the real-time measurement of redox changes occurring in live cells.We have designed and synthesized a novel reversible pro ?uorescent probe,ME-TRN,based on a rhodamine ?uorophore containing a nitroxide functional group.Here we demonstrate the successful application and in vivo evaluation of ME-TRN for the detection and quanti ?-cation of retinal oxidative status in real-time.

The retina is an ideal model for examining ROS-mediated pathological events,due to the high content of polysaturated fatty acid and high oxygen consumption (Bazan,1988;Li et al.,2009;Li and Lo,2010).The rat retinal I/R model,which mimics clinical situations such as retinal vascular occlusion disease and acute glaucoma,is an established animal model for studying retinal cell responses after an Ischemia insult (Cho et al.,2011;Sun et al.,2010).It is believed that impairment of mitochondrial integrity is a key factor in ROS-mediated neurodegeneration (Chrysostomou et al.,2013;Osborne and del Olmo-Aguado,2013).Cellular events such as disruption of ion homoeostasis,depletion of adenosine triphosphate stores and glutamate-induced excitotoxicity (Osborne et al.,2004;Pellegrini-Giampietro et al.,1990),occur during the challenge of oxidative stress (Aydemir et al.,2004;Block and Schwarz,1997;Celebi et al.,2001;Li and Lo,2010)resulting in increased levels of lipid peroxidation,depletion of free radical scavengers (Block and Schwarz,1997;Chidlow et al.,2002)and subsequent neurodegeneration.Conversely,the reduction of free radical formation and reduced oxidative stress can retard or pre-vent neuronal cell death in Ischemia retina (Chidlow et al.,2002;Dilsiz et al.,2006;Li et al.,2009;Maher and Hanneken,2008).ROS detection methods and antioxidants that target the mito-chondria are therefore of high interest and importance.

We have previously shown through confocal microscopy,that ME-TRN is taken up by living cells (RGC-5cell line and ?broblasts),and is selectively accumulated in the mitochondria (Barnett et al.,2013).Similar nitroxide hybrids have been shown to localize to the mitochondria (Smith et al.,2008).The unique potential of our nitroxide-based probe to interconvert reversibly between the sta-ble nitroxyl radical,the reduced hydroxylamine and oxidized oxoammonium forms has allowed for the ?rst time,detection of ROS and the possible bene ?ts of antioxidant therapy to be moni-tored in vivo ,in real time.

The ME-TRN probe response is driven by the overall reducing processes of the cellular environment and,in particular,by the mitochondria.The presence of the stable radical during oxidation short-circuits the normal ?uorescence effect and so these systems possess low inherent ?uorescent emission.Upon metabolism,redox processes or free radical scavenging reactions,the free radical is converted to the non-radical species that displays the bright ?uorescence of the inherent chromophore (Blough and Simpson,1988;Morrow et al.,2010).Previously,this redox-response of the probe was observed i n vitro by stimulating superoxide production in ?broblast and RGC-5cell cultures,through the inhibition of the mitochondrial respiratory chain with antimycin (Barnett et al.,2013).Here,for the ?rst time,we show a similar response in vivo (rat retina I/R injury),demonstrating a signi ?cant decrease in probe ?uorescence in response to a pro-oxidant stress.This ?

uorescence

Fig.5.Quanti ?cation of ME-TRN ?uorescence captured in the rat fundus in vivo during 60min of reperfusion following an acute ischaemic insult.Data presented as the change in ?uorescence intensity at each time point as a percentage of the pre-ischaemic (time ?0)value for each eye (mean ±SEM).An ischaemic insult resulted in a marked decrease in ?uorescent intensity over the 60min of reperfusion (I/R)when compared to the non-ischaemic control group,with signi ?cant reductions seen at 10,15,30,45and 60min reperfusion (*p <0.05compared with non-ischaemic control).An intraperitoneal injection of lutein (0.2mg/kg)1h prior to the ischaemic insult ameliorated the decrease in ?uorescence observed in I/R animals,with signi ?cant improvements observed after 5,10and 15min of reperfusion (y p <0.05compared with I/R alone).

C.L.Rayner et al./Experimental Eye Research 129(2014)48e 5653

decrease was time dependent(F(5,30)?2.864,p?0.031,see Fig.5), signifying the increased production and accumulation of ROS within the cellular environment during the reperfusion phase.The reduction of free radicals and oxidative stress through the admin-istration of lutein(Dilsiz et al.,2006;Li et al.,2009)successfully ameliorated the I/R-induced decrease in retinal?uorescence. Antioxidant therapy can therefore be considered somewhat effec-tive at maintaining the probe in the?uorescent reduced hydrox-ylamine state,limiting oxidation back to the nitroxyl radical form.

During the past decade,numerous studies have investigated neuroprotective strategies to reduce/prevent retinal cell death. Recently,intensive efforts have been made to explicate the neu-roprotective effects of carotenoids in ocular diseases in vivo(Li et al., 2009;Muriach et al.,2006;Sasaki et al.,2009)and in vitro(Li and Lo,2010;Nakajima et al.,2009).Various carotenoids are present in human plasma,but only the xanthophylls lutein and zeaxanthin are found in retina in considerable amounts(Junghans et al.,2001). Lutein,a potent antioxidant,has been applied in human clinical trials and shown to improve vision and retard the progression of AMD and cataract development(Chasan-Taber et al.,1999;Itagaki et al.,2006;Li et al.,2009;Li and Lo,2010;Richer et al.,2007, 2004),however the mechanism of protection is unclear and the role of lutein in Ischemia injury is limited(Li et al.,2012).In vitro studies show lutein can penetrate into cells and scavenge intra-cellular H2O2preventing cell damage(Li and Lo,2010)suggesting a possible therapeutic bene?t to antioxidant intervention for dis-eases linked to oxidative stress.Our present results con?rm that a single administration of lutein provides a degree of protection against oxidative stress.Whether a prolonged diet rich in antioxi-dants prior to a future Ischemia injury could mitigate the delete-rious effects of ROS requires further investigation.

This study highlights the ability of the novel ME-TRN probe to detect,visualize and quantify oxidative stress in vivo.ERG analysis of a-and b-waves and OPs,also demonstrated that intraocular in-jection of ME-TRN had no effect on the functional integrity of the retina(Fig.2).Moreover,normal retinal status was con?rmed in ME-TRN treated retinas through immunohistochemical studies: GFAP expression remained con?ned to astrocytes and IBA-1 labelled microglia demonstrated minimal activation.This was in stark contrast to the glial cell activation we and others see in injured retinas(Fig.3)(Larsen and Osborne,1996;Naskar et al., 2002;Wang et al.,2000).These data suggest that ME-TRN can be safely administered in the eye to monitor the dynamic processes of oxidative stress.In this study,we used ME-TRN to detect ROS production in an acute model of ischaemia,which predominantly induces inner retinal damage.Fig.1demonstrates that ME-TRN is not only taken up by the inner retinal neurons,but is also avidly accumulated in the outer nuclear layer.The advantage of ME-TRN accumulation throughout the retina should also allow the detec-tion of ROS production in models of outer retinal disease such as age-related macular degeneration and retinal dystrophies.

5.Conclusion

In summary,this study documents a new technique for the real-time measurement of retinal oxidative status in vivo.This could potentially have a major impact on the ability to assess putative neuroprotective antioxidants for the treatment of retinal and other neurodegenerative diseases.The mechanisms underlying retinal degeneration in a number of ocular disease states like glaucoma, age-related macular degeneration and retinal ischaemia are com-plex.However it is becoming increasingly evident that mitochon-drial dysfunction,superoxide generation and oxidative stress play a signi?cant role.The ability to quantify such changes in vivo is of great value.Reversible PFN probes provide a possible avenue for this quanti?cation.The ME-TRN probe has proven effective at detecting alterations in the cellular redox status in vivo and hence provides a unique investigative tool allowing real-time insight into a variety of disorders linked to oxidative stress.

Con?icts of interest

The authors report no con?ict of interest.

Author contribution

The authors alone are responsible for the content and writing of this paper.

CLR conducted much of the experimental work including the induction of ischaemia/reperfusion,?uorescence imaging,immu-nohistochemistry and electroretinography,and wrote the?rst draft of the manuscript.

GAG conducted and provided guidance for intraocular injections and fundus imaging.He provided signi?cant intellectual input into the?nal manuscript.

SEB,as the developer of the ME-TRN probe,was involved in the conception of the project and all intellectual aspects of the nitro-xide chemistry.He provided signi?cant input into the?nal manuscript.

NLB conceived and designed the project,conducted all initial experiments,analysed the data and provided signi?cant input into the?nal manuscript.

Acknowledgements

This research was supported by an Ophthalmic Research Insti-tute of Australia(ORIA)grant to NLB,GAG&SEB,the Australian Research Council Centre of Excellence for Free Radical Chemistry and Biotechnology(CE0561607)and the Queensland Eye Institute Foundation.We thank Dr.Paul Jackway for his statistical advice. References

Abramov, A.Y.,Scorziello, A.,Duchen,M.R.,2007.Three distinct mechanisms generate oxygen free radicals in neurons and contribute to cell death during anoxia and reoxygenation.J.Neurosci.27,1129e1138.

Ahn,H.-Y.,Fairfull-Smith,K.E.,Morrow, B.J.,Lussini,V.,Kim, B.,Bondar,M.V., Bottle,S.E.,Bel?eld,K.D.,2012.Two-photon?uorescence microscopy imaging of cellular oxidative stress using pro?uorescent nitroxides.J.Am.Chem.Soc.134, 4721e4730.

Aliev,G.,Priyadarshini,M.,Reddy,V.,Grieg,N.,Kaminsky,Y.,Cacabelos,R., Ashraf,G.,Jabir,N.,Kamal,M.,Nikolenko,V.,2013.Oxidative stress mediated mitochondrial and vascular lesions as markers in the pathogenesis of Alzheimer disease.Curr.Med.Chem.21,2208e2217.

Almasieh,M.,Wilson,A.M.,Morquette,B.,Cueva Vargas,J.L.,Di Polo,A.,2012.The molecular basis of retinal ganglion cell death in glaucoma.Prog.Retin.Eye Res.

31,152e181.

Alves-Rodrigues,A.,Shao,A.,2004.The science behind lutein.Toxicol.Lett.150, 57e83.

Arend,O.,Plange,N.,Sponsel,W.E.,Remky,A.,2004.Pathogenetic aspects of the glaucomatous optic neuropathy:?uorescein angiographic?ndings in patients with primary open angle glaucoma.Brain Res.Bull.62,517e524. Aydemir,O.,Naz?ro g lu,M.,?elebi,S.,Y?lmaz,T.,Kükner,A.S?.,2004.Antioxidant effects of alpha-,gamma-and succinate-tocopherols in guinea pig retina during

ischemia-reperfusion injury.Pathophysiology11,167e171.

Azad,M.B.,Chen,Y.,Gibson,S.B.,2009.Regulation of autophagy by reactive oxygen species(ROS):implications for cancer progression and treatment.Antioxid.

Redox Signal.11,777e790.

Barnett,N.L.,Gole,G.A.,Rayner,C.L.,Chong,K.L.,Bottle,S.E.,2013.Evaluation of a novel?uorescent probe for the assessment of retinal oxidative status.Clin.Exp.

Ophthalmol41,126e126.

Barnham,K.J.,Masters, C.L.,Bush, A.I.,2004.Neurodegenerative diseases and oxidative stress.Nat.Rev.Drug Discov.3,205e214.

Bazan,N.G.,1988.The metabolism of omega-3polyunsaturated fatty acids in the eye:the possible role of docosahexaenoic acid and docosanoids in retinal physiology and ocular pathology.Prog.Clin.Biol.Res.312,95e112.

C.L.Rayner et al./Experimental Eye Research129(2014)48e56 54

Belkin,S.,Mehlhorn,R.J.,Hideg,K.,Hankovsky,O.,Packer,L.,1987.Reduction and destruction rates of nitroxide spin probes.Arch.Biochem.Biophys.256, 232e243.

Block,F.,Schwarz,M.,1997.Effects of antioxidants on ischemic retinal dysfunction.

Exp.Eye Res.64,559e564.

Blough,N.V.,Simpson,D.J.,1988.Chemically mediated?uorescence yield switching in nitroxide-?uorophore adducts:optical sensors of radical/redox reactions.

J.Am.Chem.Soc.110,1915e1917.

Bush,R.A.,Sieving,P.A.,1996.Inner retinal contributions to the primate photopic fast?icker electroretinogram.J.Opt.Soc.Am.A13,557e565.

Celebi,S.,Dilsiz,N.,Yilmaz,T.,Kükner,A.S.,2001.Effects of melatonin,vitamin E and octreotide on lipid peroxidation during ischemia-reperfusion in the guinea pig retina.Eur.J.Ophthalmol.12,77e83.

Chasan-Taber,L.,Willett,W.C.,Seddon,J.M.,Stampfer,M.J.,Rosner,B.,Colditz,G.A., Speizer, F.E.,Hankinson,S.E.,1999.A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women.Am.J.Clin.Nutr.

70,509e516.

Chen,Y.,McMillan-Ward,E.,Kong,J.,Israels,S.J.,Gibson,S.B.,2007.Mitochondrial electron-transport-chain inhibitors of complexes I and II induce autophagic cell death mediated by reactive oxygen species.J.Cell Sci.120,4155e4166. Chidlow,G.,Schmidt,K.-G.,Wood,J.,Melena,J.,Osborne,N.,2002.a-lipoic acid protects the retina against ischemia-reperfusion.Neuropharmacology43, 1015e1025.

Cho,K.J.,Kim,J.H.,Park,H.-Y.L.,Park, C.K.,2011.Glial cell response and iNOS expression in the optic nerve head and retina of the rat following acute high IOP ischemia-reperfusion.Brain Res.1403,67e77.

Chrysostomou,V.,Rezania,F.,Trounce,I.A.,Crowston,J.G.,2013.Oxidative stress and mitochondrial dysfunction in glaucoma.Curr.Opin.Pharmacol.13, 12e15.

Chucair,A.J.,Rotstein,N.P.,SanGiovanni,J.P.,During,A.,Chew,E.Y.,Politi,L.E.,2007.

Lutein and zeaxanthin protect photoreceptors from apoptosis induced by oxidative stress:relation with docosahexaenoic acid.Investig.Ophthalmol.Vis.

Sci.48,5168e5177.

Chung,H.S.,Harris,A.,Evans,D.W.,Kagemann,L.,Garzozi,H.J.,Martin,B.,1999.

Vascular aspects in the pathophysiology of glaucomatous optic neuropathy.

Surv.Ophthalmol.43,S43e S50.

Dilsiz,N.,Sahaboglu,A.,Y?ld?z,M.Z.,Reichenbach,A.,2006.Protective effects of various antioxidants during ischemia-reperfusion in the rat retina.Graefe's Arch.Clin.Exp.Ophthalmol.244,627e633.

Dirani,M.,Crowston,J.G.,Taylor,P.S.,Moore,P.T.,Rogers,S.,Pezzullo,M.L., Keeffe,J.E.,Taylor,H.R.,2011.Economic impact of primary open-angle glaucoma in Australia.Clin.Exp.Ophthalmol.39,623e632.

Fernandez-Suarez,M.,Ting, A.Y.,2008.Fluorescent probes for super-resolution imaging in living cells.Nat.Rev.Mol.Cell Biol.9,929e943.

Green,S.A.,Simpson, D.J.,Zhou,G.,Ho,P.S.,Blough,N.V.,1990.Intramolecular quenching of excited singlet states by stable nitroxyl radicals.J.Am.Chem.Soc.

112,7337e7346.

Hall,J.K.,Andrews,A.P.,Walker,R.,Piltz-Seymour,J.R.,2001.Association of retinal vessel caliber and visual?eld defects in glaucoma.Am.J.Ophthalmol.132, 855e859.

Halliwell,B.,Whiteman,M.,2004.Measuring reactive species and oxidative dam-age in vivo and in cell culture:how should you do it and what do the results mean?Br.J.Pharmacol.142,231e255.

Hamanaka,R.B.,Chandel,N.S.,2010.Mitochondrial reactive oxygen species regulate cellular signaling and dictate biological outcomes.Trends Biochem.Sci.35, 505e513.

Hess,M.L.,Manson,N.H.,1984.Molecular oxygen:friend and foe:the role of the oxygen free radical system in the calcium paradox,the oxygen paradox and ischemia/reperfusion injury.J.Mol.Cell.Cardiol.16,969e985.

Hirosawa,S.,Arai,S.,Takeoka,S.,2012.A TEMPO-conjugated?uorescent probe for monitoring mitochondrial redox https://www.wendangku.net/doc/a01952276.html,mun.48,4845e4847. Holcombe,D.J.,Lengefeld,N.,Gole,G.A.,Barnett,N.L.,2008.The effects of acute intraocular pressure elevation on rat retinal glutamate transport.Acta Oph-thalmol.86,408e414.

Hood,D.C.,Birch,D.G.,1996.b wave of the scotopic(rod)electroretinogram as a measure of the activity of human on-bipolar cells.J.Opt.Soc.Am.A13, 623e633.

Hughes,W.F.,1991.Quantitation of ischemic damage in the rat retina.Exp.Eye Res.

53,573e582.

Itagaki,S.,Ogura,W.,Sato,Y.,Noda,T.,Hirano,T.,Mizuno,S.,Iseki,K.,2006.

Characterization of the disposition of lutein after iv administration to rats.Biol.

Pharm.Bull.29,2123.

Ito,D.,Imai,Y.,Ohsawa,K.,Nakajima,K.,Fukuuchi,Y.,Kohsaka,S.,1998.Microglia-speci?c localisation of a novel calcium binding protein,Iba1.Mol.Brain Res.57, 1e9.

Johnson,L.V.,Walsh,M.L.,Chen,L.B.,1980.Localization of mitochondria in living cells with rhodamine123.Proc.Natl.Acad.Sci.77,990e994.

Junghans,A.,Sies,H.,Stahl,W.,2001.Macular pigments lutein and zeaxanthin as blue light?lters studied in liposomes.Arch.Biochem.Biophys.391,160e164. Kageyama,G.H.,Wong-Riley,M.,1984.The histochemical localization of cyto-chrome oxidase in the retina and lateral geniculate nucleus of the ferret,cat, and monkey,with particular reference to retinal mosaics and ON/OFF-center visual channels.J.Neurosci.4,2445e2459.

Kif?n,R.,Bandyopadhyay,U.,Cuervo,A.M.,2006.Oxidative stress and autophagy.

Antioxid.Redox Signal.8,152e162.Kuroiwa,S.,Katai,N.,Shibuki,H.,Kurokawa,T.,Umihira,J.,Nikaido,T.,Kametani,K., Yoshimura,N.,1998.Expression of cell cycle-related genes in dying cells in retinal ischemic injury.Investig.Ophthalmol.Vis.Sci.39,610e617.

Larsen,A.K.,Osborne,N.N.,1996.Involvement of adenosine in retinal ischemia.

Studies on the rat.Investig.Ophthalmol.Vis.Sci.37,2603e2611. Lemasters,J.J.,2005.Selective mitochondrial autophagy,or mitophagy,as a targeted defense against oxidative stress,mitochondrial dysfunction,and aging.Reju-venation Res.8,3e5.

Li,S.-Y.,Lo,A.C.Y.,2010.Lutein protects RGC-5cells against hypoxia and oxidative stress.Int.J.Mol.Sci.11,2109e2117.

Li,S.-Y.,Fu,Z.-J.,Ma,H.,Jang,W.-C.,So,K.-F.,Wong,D.,Lo,A.C.Y.,2009.Effect of lutein on retinal neurons and oxidative stress in a model of acute retinal ischemia/reperfusion.Investig.Ophthalmol.Vis.Sci.50,836e843.

Li,S.-Y.,Fung,F.K.C.,Fu,Z.J.,Wong,D.,Chan,H.H.L.,Lo,A.C.Y.,2012.Anti-in?am-matory effects of lutein in retinal ischemic/hypoxic Injury:in vivo and in vitro studies.Investig.Ophthalmol.Vis.Sci.53,5976e5984.

Lin,M.T.,Beal,M.F.,2006.Mitochondrial dysfunction and oxidative stress in neurodegenerative diseases.Nature443,787e795.

Liu,Q.,Ju,W.-K.,Crowston,J.G.,Xie, F.,Perry,G.,Smith,M.A.,Lindsey,J.D., Weinreb,R.N.,2007.Oxidative stress is an early event in hydrostatic pressur-

e e induced retinal ganglion cell damage.Investig.Ophthalmol.Vis.Sci.48,

4580e4589.

Maher,P.,Hanneken, A.,2008.Flavonoids protect retinal ganglion cells from ischemia in vitro.Exp.Eye Res.86,366e374.

Mitchell,J.B.,Krishna,M.C.,Kuppusamy,P.,Cook,J.A.,Russo,A.,2001.Protection against oxidative stress by nitroxides.Exp.Biol.Med.226,620e621. Mitchell,P.,Leung,H.,Wang,J.J.,Rochtchina,E.,Lee,A.J.,Wong,T.Y.,Klein,R.,2005.

Retinal vessel diameter and open-angle glaucoma:the Blue Mountains Eye Study.Ophthalmology112,245e250.

Morrow,B.J.,Keddie,D.J.,Gueven,N.,Lavin,M.F.,Bottle,S.E.,2010.A novel pro-?uorescent nitroxide as a sensitive probe for the cellular redox environment.

Free Radic.Biol.Med.49,67e76.

Moxon-Lester,L.,Takamoto,K.,Colditz,P.B.,Barnett,N.L.,2009.S-Adenosyl-l-methionine restores photoreceptor function following acute retinal ischemia.

Vis.Neurosci.26,429e441.

Muriach,M.,Bosch-Morell, F.,Alexander,G.,Blomhoff,R.,Barcia,J.,Arnal, E., Almansa,I.,Romero,F.J.,Miranda,M.,2006.Lutein effect on retina and hip-pocampus of diabetic mice.Free Radic.Biol.Med.41,979e984.

Nakajima,Y.,Shimazawa,M.,Otsubo,K.,Ishibashi,T.,Hara,H.,2009.Zeaxanthin,a retinal carotenoid,protects retinal cells against oxidative stress.Curr.Eye Res.

34,311e318.

Naskar,R.,Wissing,M.,Thanos,S.,2002.Detection of early neuron degeneration and accompanying microglial responses in the retina of a rat model of glau-coma.Investig.Ophthalmol.Vis.Sci.43,2962e2968.

Nathan,C.,2003.Speci?city of a third kind:reactive oxygen and nitrogen in-termediates in cell signaling.J.Clin.Investig.111,769e778.

Oharazawa,H.,Igarashi,T.,Yokota,T.,Fujii,H.,Suzuki,H.,Machide,M., Takahashi,H.,Ohta,S.,Ohsawa,I.,2010.Protection of the retina by rapid diffusion of hydrogen:administration of hydrogen-loaded eye drops in retinal ischemia e reperfusion injury.Investig.Ophthalmol.Vis.Sci.51,487e492. Osborne,N.N.,2008.Pathogenesis of ganglion“cell death”in glaucoma and neu-roprotection:focus on ganglion cell axonal mitochondria.In:Carlo Nucci,L.C.N.N.O.,Giacinto, B.(Eds.),Progress in Brain Research.Elsevier, pp.339e352.

Osborne,N.N.,del Olmo-Aguado,S.,2013.Maintenance of retinal ganglion cell mitochondrial functions as a neuroprotective strategy in glaucoma.Curr.Opin.

Pharmacol.13,16e22.

Osborne,N.N.,Casson,R.J.,Wood,J.P.M.,Chidlow,G.,Graham,M.,Melena,J.,2004.

Retinal ischemia:mechanisms of damage and potential therapeutic strategies.

Prog.Retin.Eye Res.23,91e147.

Pellegrini-Giampietro, D.E.,Cherici,G.,Alesiani,M.,Carla,V.,Moroni, F.,1990.

Excitatory amino acid release and free radical formation may cooperate in the genesis of ischemia-induced neuronal damage.J.Neurosci.10,1035e1041. Penn,R.,Hagins,W.,1969.Signal transmission along retinal rods and the origin of the electroretinographic a-wave.Nature223,201e204.

Ray,A.,Martinez,B.,Berkowitz,L.,Caldwell,G.,Caldwell,K.,2014.Mitochondrial dysfunction,oxidative stress,and neurodegeneration elicited by a bacterial metabolite in a C.elegans Parkinson's model.Cell Death Dis.5,e984. Richer,S.,Stiles,W.,Statkute,L.,Pulido,J.,Frankowski,J.,Rudy, D.,Pei,K., Tsipursky,M.,Nyland,J.,2004.Double-masked,placebo-controlled,random-ized trial of lutein and antioxidant supplementation in the intervention of atrophic age-related macular degeneration:the Veterans LAST study(Lutein Antioxidant Supplementation Trial).Optom.J.Am.Optom.Assoc.75,216e229. Richer,S.,Devenport,J.,Lang,J.C.,https://www.wendangku.net/doc/a01952276.html,ST II:differential temporal responses of macular pigment optical density in patients with atrophic age-related macular degeneration to dietary supplementation with xanthophylls.Optom.J.Am.

Optom.Assoc.78,213e219.

Robson,J.,Frishman,L.,1995.Response linearity and kinetics of the cat retina:the bipolar cell component of the dark-adapted electroretinogram.Vis.Neurosci.

12,837e850.

Robson,J.G.,Frishman,L.J.,1998.Dissecting the dark-adapted electroretinogram.

Doc.Ophthalmol.95,187e215.

Sasaki,M.,Ozawa,Y.,Kurihara,T.,Noda,K.,Imamura,Y.,Kobayashi,S.,Ishida,S., Tsubota,K.,2009.Neuroprotective effect of an antioxidant,lutein,during retinal in?ammation.Investig.Ophthalmol.Vis.Sci.50,1433e1439.

C.L.Rayner et al./Experimental Eye Research129(2014)48e5655

Scherz-Shouval,R.,Elazar,Z.,2007.ROS,mitochondria and the regulation of auto-phagy.Trends Cell Biol.17,422e427.

Scherz-Shouval,R.,Elazar,Z.,2011.Regulation of autophagy by ROS:physiology and pathology.Trends Biochem.Sci.36,30e38.

Scherz-Shouval,R.,Shvets,E.,Fass,E.,Shorer,H.,Gil,L.,Elazar,Z.,2007.Reactive oxygen species are essential for autophagy and speci?cally regulate the activity of Atg4.EMBO J.26,1749e1760.

Schwarz,K.,Siddiqi,N.,Singh,S.,Neil,C.J.,Dawson,D.K.,Frenneaux,M.P.,2014.The breathing heart d mitochondrial respiratory chain dysfunction in cardiac dis-ease.Int.J.Cardiol.171,134e143.

Seo,S.-j.,Krebs,M.P.,Mao,H.,Jones,K.,Conners,M.,Lewin,A.S.,2012.Pathological consequences of long-term mitochondrial oxidative stress in the mouse retinal pigment epithelium.Exp.Eye Res.101,60e71.

Sieving,P.A.,Murayama,K.,Naarendorp,F.,1994.Push e pull model of the primate photopic electroretinogram:a role for hyperpolarizing neurons in shaping the b-wave.Vis.Neurosci.11,519e532.

Smith,R.A.J.,Adlam,V.J.,Blaikie,F.H.,Manas,A.-R.B.,Porteous,C.M.,James,A.M., Ross,M.F.,Logan, A.,Cochem e,H.M.,Trnka,J.,Prime,T.A.,Abakumova,I., Jones,B.A.,Filipovska,A.,Murphy,M.P.,2008.Mitochondria-targeted antioxi-dants in the treatment of disease.Ann.N.Y.Acad.Sci.1147,105e111.

Streit,W.J.,Graeber,M.B.,Kreutzberg,G.W.,1988.Functional plasticity of microglia:

a review.Glia1,301e307.

Sun,M.-H.,Pang,J.-H.S.,Chen,S.-L.,Han,W.-H.,Ho,T.-C.,Chen,K.-J.,Kao,L.-Y., Lin,K.-K.,Tsao,Y.-P.,2010.Retinal protection from acute glaucoma-induced ischemia-reperfusion injury through pharmacologic induction of heme oxy-genase-1.Investig.Ophthalmol.Vis.Sci.51,4798e4808.

Swartz,H.M.,https://www.wendangku.net/doc/a01952276.html,e of nitroxides to measure redox metabolism in cells and tissues.J.Chem.Soc.Faraday Trans.1Phys.Chem.Condens.Phases83,191e202. Swartz,H.M.,1990.Principles of the metabolism of nitroxides and their implica-tions for spin trapping.Free https://www.wendangku.net/doc/a01952276.html,mun.9,399e405.Tezel,G.,2006.Oxidative stress in glaucomatous neurodegeneration:mechanisms and consequences.Prog.Retin.Eye Res.25,490e513.

Wachtmeister,L.,Dowling,J.E.,1978.The oscillatory potentials of the mudpuppy retina.Investig.Ophthalmol.Vis.Sci.17,1176e1188.

Wang,X.,Tay,S.S.-W.,Ng,Y.-K.,2000.An immunohistochemical study of neuronal and glial cell reactions in retinae of rats with experimental glaucoma.Exp.Brain Res.132,476e484.

Wang,B.,Li,P.,Yu,F.,Chen,J.,Qu,Z.,Han,K.,2013.A near-infrared reversible and ratiometric?uorescent probe based on Se-BODIPY for the redox cycle mediated by hypobromous acid and hydrogen sul?de in living https://www.wendangku.net/doc/a01952276.html,mun.49, 5790e5792.

Wardman,P.,2007.Fluorescent and luminescent probes for measurement of oxidative and nitrosative species in cells and tissues:progress,pitfalls,and prospects.Free Radic.Biol.Med.43,995e1022.

Wen-Xue,Q.,Xu,W.,2012.Progress on?uorescent probes for reversible redox cycles and their application in living cell imaging.Chin.J.Anal.Chem.40,1301. Wilkinson-Berka,J.L.,Rana,I.,Armani,R.,Agrotis,A.,2013.Reactive oxygen species, Nox and angiotensin II in angiogenesis:implications for retinopathy.Clin.Sci.

124,597e615.

Xu,K.,Qiang,M.,Gao,W.,Su,R.,Li,N.,Gao,Y.,Xie,Y.,Kong,F.,Tang,B.,2013.A near-infrared reversible?uorescent probe for real-time imaging of redox status changes in vivo.Chem.Sci.4,1079e1086.

Yapici,N.B.,Jockusch,S.,Moscatelli,A.,Mandalapu,S.R.,Itagaki,Y.,Bates,D.K., Wiseman,S.,Gibson,K.M.,Turro,N.J.,Bi,L.,2011.New rhodamine nitroxide based?uorescent probes for intracellular hydroxyl radical identi?cation in living https://www.wendangku.net/doc/a01952276.html,.Lett.14,50e53.

Yuki,K.,Ozawa,Y.,Yoshida,T.,Kurihara,T.,Hirasawa,M.,Ozeki,N.,Shiba, D., Noda,K.,Ishida,S.,Tsubota,K.,2011.Retinal ganglion cell loss in superoxide dismutase1de?ciency.Investig.Ophthalmol.Vis.Sci.52,4143e4150.

C.L.Rayner et al./Experimental Eye Research129(2014)48e56 56

第三节 氧化剂和还原剂

第二章元素与物质世界 第三节氧化剂和还原剂——第一课时 编制：何永平审核：董海滨编制时间：2011年10月一、氧化还原反应 【问题1】你学过哪些反应类型？什么样的反应是氧化还原反应？ 【交流研讨1】请你写出下列化学反应的方程式，并标出所有元素的化合价，观察哪些元素的化合价改变了，哪些元素的化合价没变。 ①铜和氧气的反应 . ②氧化铜和氢气的反应 . ③铁与硫酸铜溶液的反应 . ④碳酸钙高温分解 . ⑤硝酸银与氯化钠反应 . 【问题2】根据元素在化学反应前后化合价是否发生改变，可以将化学反应分为哪两类？分别怎样定义？上述5个反应分别属于哪一种？判断一个反应是否属于氧化还原反应的依据是什么？ 【问题3】什么是氧化反应？什么是还原反应？二者有何关系？ 下列变化属于氧化反应的是（），还原反应的是（） A．HCl→H2B．Mg→Mg2+ C．Cl-→AgCl D．CuO→Cu

【交流研讨2】通过前面的学习，我们知道钠可以在氯气中剧烈燃烧生成氯化钠，这个反应属于氧化还原反应吗？为什么？钠原子和氯原子是经过怎样的变化形成氯化钠的呢？ 【问题4】氧化还原反应的实质是什么？元素化合价的升降与此有何关系？ 【问题5】氧化还原反应中电子转移和元素化合价的升降情况可以用什么方式表示？（以氢气还原氧化铜为例分别用两种方式表示） 【巩固练习】 1、判断下列反应哪些属于氧化还原反应( ) A. Cu+Cl2=CuCl2 B. Zn+2H+=Zn2++H2↑ C. CaCO3+2H+=Ca2++H2O+CO2↑ D. BaCl2+H2SO4=BaSO4↓+2HCl E. Fe2O3+3CO=2Fe+3CO2 2、下列反应属于氧化反应的是( ) A. Na2O →NaOH B. CO2→CO32- C. Fe2O3→Fe D. Cl2→HClO 3、下列变化过程属于还原反应的是（） A．Cl-→AgCl B．Mg→Mg2+ C．HCl→H2D．CuO→Cu2+ 4、有关氧化还原反应的叙述正确的是（） A．氧化还原反应的实质是有氧元素的得失 B．氧化还原反应的实质是元素化合价的升降 C．氧化还原反应的实质是电子的转移 D．物质所含元素化合价升高的反应是还原反应 5、写出金属钠与硫酸铜溶液反应的两个离子方程式，并判断是否为氧化还原反应 *分析上述氧化还原反应中电子的转移和化合价升降的关系

高纯三氧化钼激光粒度分布的测定与分析

收稿日期:2003-02-14 作者简介:王新刚,男,1969年生,西安交通大学材料科学与工程学 院博士生。 高纯三氧化钼激光粒度分布的测定与分析 王新刚1,2　唐利侠2 (1西安交通大学材料科学与工程学院　西安　710049) (2金堆城钼业公司技术中心　西安　710068 ) 摘　要　用扫描电镜观察了高纯三氧化钼的形貌,高纯三氧化钼是长条状的单颗粒聚集成的团聚体。用激光粒度仪的干法测定了高纯三氧化钼团聚体的激光粒度分布,用水作分散剂测定了高纯三氧化钼分散体的激光粒度分布,结果表明高纯三氧化钼的激光粒度分布值与电镜测量的颗粒及颗粒团尺寸一致,这样的测试方法能全面正确地反映高纯三氧化钼粒度的特征。讨论了高纯三氧化钼激光粒度分布对后续的还原过程及钼粉质量的影响。 关键词　高纯三氧化钼　激光粒度分布　团聚颗粒　分散颗粒 中图分类号:TG 115.21 文献标识码:A 文章编号:1006-2602(2003)02-0067-04 MEASUREMENT AN D ANALYSIS OF LASER PARTIC L E -SIZE DISTRIBUTION OF HIGH -PURIT Y TRIOXIDE MOLYB DENUM POWDER Wang Xingang 1,2　Tang Lixia 2 (1School of Materials Science and Engineering of Xi ’an Jiaotong University ,Xi ’an 710049) (2Technical Center of Jinduicheng Molybdenum Mining Corporation ,Xi ’an 710068) Abstract The SEM morphology of high -purity trioxide molybdenum powder was observed.High -purity tri 2oxide molybdenum powder was agglomerated particles which consisted of primary strip particles.The particle -size distribution of agglomerated particles was measured using dry -dispersion method of Malvern Mastersizer 2000,and deagglomerated particle -size distribution was determined with water as dispersant.The results showed that the laser particle -size distribution was same as that examined by SEM ,and this kind of method could completely and accurately analyze characteristics of particle size of high -purity trioxide molybdenum pow 2der.It was discussed that the laser particle -size distribution of high -purity trioxide molybdenum powder influ 2enced subsequent t hydrogen -reduction process and quality of molybdenum powder. K ey w ords High 2purity trioxide molybdenum ,Laser particle -size distribution ,Agglomerated particle ,Deag 2glomerated particle 1　前　言 高纯三氧化钼是钼制品深加工的主要原料,尤 其在发达国家,许多钼制品生产厂家出于环保的要求,逐渐采用高纯三氧化钼代替钼酸铵作为钼制品生产的原料,高纯三氧化钼是直接影响到后续加工质量的关键[1]。国内的难熔金属行业对于高纯三氧化钼的技术条件的要求主要是强调其化学纯度、平均费氏粒度、松装密度及表观质量,一般不对其粒度分布进行测定和控制。实际上高纯三氧化钼的粒 度分布及其控制对其后的还原过程和钼粉质量起到关键作用。 粉末中能单独分开并独立存在的最小实体称为单颗粒,单颗粒以某种形式聚集而成为二次颗粒,其中的原始颗粒就称为一次颗粒[2-4]。高纯三氧化钼是由单颗粒依靠范德华力粘结而成的,对于其二次颗粒我们称之为团聚体(agglomerated paticle ),一次颗粒称为分散体(deagglomerated paticle )。对于粉末粒度的测定方法,激光散射式粒度测试仪已取得一致公认并得到了广泛的应用[5-7]。本文测定了高纯三氧化钼团聚体及分散体的激光粒度分布,分析其对后续还原过程的影响。 第27卷第2期2003年4月 中　国　钼　业CHINA MOL Y BDENUM INDUSTR Y Vol.27No.2 April 2003

(完整版)氧化还原反应习题及答案详解

精心整理 氧化还原反应 1．下列有关氧化还原反应的叙述正确的是() A．元素化合价升高的反应是还原反应 B．物质在变化中失去了电子，此物质中的某一元素化合价降低 C．有电子转移的反应就是氧化还原反应 D．有化合价升降的反应，不一定是氧化还原反应 答案 解析 2 A．Fe2 B．NH4 C． D．CuO 答案 解析 3 A B C D 答案 解析氧化还原反应中可能只有一种元素的化合价变化；有单质参加的化合反应或者有单质生成的分解反应属于氧化还原反应。 4．下列变化中只有通过还原反应才能实现的是() A．Fe3＋―→Fe2＋B．Mn2＋―→MnO C．Cl－―→Cl2D．N2O3―→HNO2 答案 A 解析发生还原反应时，元素的化合价降低。B中锰元素化合价由＋2价升高为＋7价，C中氯元

素的化合价由－1价升高为0价，D中元素的化合价无变化。 5．日常生活中的许多现象与化学反应有关，下列现象与氧化还原反应无关的是() A．铜铸塑像上出现铜绿[Cu2(OH)2CO3] B．充有氢气的气球遇明火爆炸 C．大理石雕像被酸雨腐蚀毁坏 D．铁质菜刀生锈 答案 C 解析A中铜元素的化合价由0价升高为＋2价；B中氢气爆炸后生成水，元素化合价由0价变为 ＋1 6 A．Zn B．2H2 C．H2＋ D．2H2 答案 解析A中＋2价Cu 7 A． B．2Fe2 C． D．Na2 答案 解析 8．已知某两种物质在一定条件下能发生化学反应，其反应的微观示意图如下，则下列说法正确的是() (说明：一种小球代表一种元素的原子) A．图中的反应物都是化合物 B．该反应属于置换反应 C．该反应属于非氧化还原反应 D．该反应不符合质量守恒定律

专题04 氧化还原反应

1．下列变化中，气体被还原的是（ ） A ．二氧化碳使Na 2O 2固体变白 B ．氯气使KBr 溶液变黄 C ．乙烯使Br 2的四氯化碳溶液褪色 D ．氨气使AlCl 3溶液产生白色沉淀 2．下列能量转化过程与氧化还原反应无关的是（ ） A ．硅太阳能电池工作时，光能转化成电能 B ．锂离子电池放电时，化学能转化成电能 C ．电解质溶液导电时，电能转化成化学能 D ．葡萄糖为人类生命活动提供能量时，化学能转化成热能 3．向含amolNaClO 的溶液通入bmolSO 2充分反应（不考虑二氧化硫与水之间的反应以及次氯酸的分 解）。下列说法不正确的是（ ） A ．当0Cu 2+>Fe 2+ 。若在氯化铁 溶液蚀刻铜印刷电路板后所得的溶液里加入过量锌片。下列说法正确的是（ ）

人教版必修一《氧化还原反应》三课时优秀教案

人教版必修一《氧化还原反应》三课时优秀教案氧化还原反应（第1课时） 教学目标概览 （一）知识目标 1、巩固初中四种基本反应类型知识、初中氧化反应和还原反应知识。 2、用化合价变化的观点和电子转移的观点加深对氧化反应、还原反应等概念的理解。 （二）能力目标 通过判断一个反应是否是氧化还原，培养学生的逻辑思维能力。 （三）情感目标 培养学生能用辨证的对立统一的观点分析事物的意识。 重点与难点： 巩固初中化学反应分类的知识和主要反应类型的知识，并加深认识。 教学方法：设疑、比较、讨论、讲解、练习 教学过程： 一、化学反应类型 1．基本反应类型 ［讨论］以上反应类型的分类依据是什么? ［小结］依据反应物和生成物的类别及种类来区分。 ［思考］Fe 2O 3 ＋3CO=== 2Fe+3CO 2 、CH 4 ＋2O 2 ====CO 2 ＋2H 2 O两反应属何种基本反应类型? ［小结］不属于基本反应类型中的任何一种，说明此种分类方法不能囊括所有化学反应，不能反映所有化学反应的本质。根据上面二个反应可以知道．四种基本类型反应不能包括所有反应，且不能反映化学反应本质。氧化反应和还原反应的分类也没有反映反应的本质。 练习：各写出一个符合下列条件的有关化学方程式。 1．两种单质化合；两种化合物化合；单质与化合物化合。 2．一种物质分解成两种物质；一种物质分解成三种物质。 3．非金属单质置换非金属单质；金属单质置换金属单质。 4．复分解反应：氧化物与酸、氧化物与碱、酸与碱、酸与盐、盐与盐反应。 [讲述：]化学反应还有其他分类方法。例如，从得失氧的角度去分类，我们还学习了氧化反应和还原反应。 二、氧化还原反应： 1、实验分析： 高温点燃

高中化学 氧化还原反应专题练习(带答案)上课讲义

氧化还原反应专题练习 可能用到的相对原子质量：H-1 N-14 O-16 C-23 一、选择题 1．硒是人体微量元素中的“抗癌之王”，补充适量的硒还可以延缓衰老。中国科学家尝试用Na2SeO3清除人体内能加速人体衰老的活性氧。下面有关Na2SeO3在该反应的作用说法正确的是（） A．该反应中是还原剂B．既是氧化剂又是还原剂 C．反应过程中Se的化合价从+2→+4 D．既不是氧化剂又不是还原剂 2．氢化亚铜（CuH）是一种难溶的物质，可用CuSO4溶液和“另一种物质”在40oC~50oC时反应来制备，CuH 不稳定，它既能与HCl反应产生气体，又能在氯气中燃烧，以下有关判断不正确的是（） A．CuH既可做氧化剂又可做还原剂 B．另一种物质一定具有还原性 C．CuH跟HCl反应的化学方程式为：2CuH+2HCl=CuCl2+2H2↑+Cu D．CuH在Cl2燃烧的化学方程式为：CuH+Cl2 CuCl+HCl 3．下列叙述中正确的是 A．元素的单质可由氧化含该元素的化合物来制得 B．失电子越多的还原剂，其还原性就越强 C．阳离子只能得电子被还原，作氧化剂 D．含有最高价元素的化合物一定具有强氧化性 4．据广州日报：2008年2月23日深圳市龙岗宝龙工业区小食店发生疑似食物中毒事件，经调查该事件已正式确定为食品或水受到亚硝酸盐污染而引起的中毒事件。为了食品安全，可以用酸性高锰酸钾溶液进行滴定实验，定量检测NaNO2的含量：NO2－＋MnO4－＋H＋NO3－＋Mn2＋＋H2O（未配平）。下列叙述中错误的是A．滴定过程中不需加入指示剂 B．滴定实验后溶液的pH增大 C．滴定实验时酸性高锰酸钾溶液盛装在碱式滴定管中 D．1molKMnO4参加反应时消耗2.5molNaNO2 5．在一定条件下，硫酸铵的分解反应为:4(NH4)2SO4=N2↑+6NH3↑+3SO2↑+SO3↑+7H2O，当有n mol电子转移时，下列说法正确的是:

NO1重要的氧化剂和还原剂.

N0.1重要的氧化剂和还原剂 教学目标： 1 ?从得失电子的角度加深对氧化还原反应及氧化剂、还原剂的理解，了解氧化产物和还原产物。 2?掌握氧化剂、还原剂中所含元素化合价的情况，掌握用单线桥表示氧化还原反应的电子转移情况。 3?掌握重要的氧化剂、还原剂的常见反应；学会比较氧化剂、还原剂的相对强弱。教学过程： 一、用单线桥表示下列反应，并指明氧化剂与还原剂 (1)Fe + H2SO4 = FeS04 + H2f ⑵ 2H2 + 02 = 2H2O (3)CI2 + H20 = HCl + HC10 二、分析并配平下列氧化还原反应，指出氧化剂，还原剂，氧化产物，还原产物，标出电子转移的方向和数目 (1)_KCI0 3 + _HCI ——_ KCI + _CI2 + ____________ (2)CI2 + ~N H3N2 + HCI (3)_NO + _NH3 ——_N2 +_H20 三、读课本24页，请归纳：—— 氧化还原反应的实质是________________________________________________________ ， 判断氧化还原反应的依据 四、讲解图3—2,并 1 ?下列下画线的元素是被氧化还是被还原，要加氧化剂还是加还原剂才能实现 (1) Kl_—J2 ⑵SO2— S03 HgCI 2— ⑷NO2—H N03 (5) FeCl3—FeCl2 2.IBr + H 20 = HBr + HI0 是氧化还原反应吗？为什么？ 3.S02与H2S可发生下列反应，S02 + 2H2S = 3S + 2H 20，当生成硫48 g时，氧化产物比还原产物多还是少多 ?两者相差少克？ N0.2氧化还原反应： 1：判断下列那些为氧化还原反应，并说出理由 IBr + H 20 = HBr + HI0 K0H+CI 2=KCI +KCI0+H 20 NaH+H 20 =Na0H+H 2 Ca02+H20 =Ca(OH) 2 +H 2O2 5C2H5OH +2KMnO 4+3H2SO4 —5CH3CHO +K 2SO4+2MnSO 4 +8H2O 氧化还原反应的实质是_______________________________________________________ 判断氧化还原反应的依据是__________________________________________ 。 小结：氧化还原反应发生规律和有关概念。

氧化还原反应教案第一课时.

氧化还原反应 【教学目的】 1．初步掌握根据化合价的变化和电子转移的观点分析氧化—还原反应的方法。 2．从电子转移的观点理解氧化—还原反应实质并能简单运用。 3．初步学习对立统一的辩证唯物主义观点。 【重点和难点】 1．氧化—还原反应的分析方法和实质。 2．用化合价变化和电子转移的观点认识氧化、还原，氧化性、还原性；判断氧化剂和还原剂。 3．氧化—还原反应的电子得失结果（双线桥）和电子转移情况（单线桥）两种表示方法。 【教学过程】 第一课时 【设问】（投影片或小黑板） 1．举例说明什么是氧化反应？还原反应？并指出反应中的氧化剂、还原剂（要求从物质的得氧与失氧进行分析）。 2．以氢气还原氧化铜的反应为例，从得氧、失氧和化合价的变化说明什么是氧化—还原反应？ 3．从化合价变化分析以下反应： （1）2Mg+O22MgO （2）CO+CuO Cu+CO2 （3）2Na+CI2=2NaCI （4）CaO+H2O=Ca(OH2 4．以反应（3）为例说明元素化合价变化的原因。

一、氧化—还原反应 1．得氧、失氧只是氧化—还原反应的表观认识。 物质得到氧的反应叫氧化反应，该反应物是还原剂；物质失去氧的反应叫还原反应，该反应物是氧化剂。一种物质被氧化，同时另一种物质被还原的反应叫氧化—还原反应。 根据质量守恒定律，化学反应前、后原子的种类、个数不变。氢气得氧与氧化铜失氧的反应必然同时发生，因此氧化与还原这两个相反的反应必然同时发生在同一反应中，称为氧化—还原反应。 2．元素化合价的变化是氧化—还原反应的特征。 物质的得氧、失氧必然导致物质所含元素化合价的变化。此种认识更接近氧化—还原反应的本质。 指导学生分析设问3所涉及的四个反应。 此反应是氧化—还原反应，且反应物中都有氧元素，但氧化、还原反应发生在碳与铜元素之间，与氧元素无关。

氧化还原反应经典练习题目

氧化还原反应练习题 一、选择题 1.下列反应一定属于氧化还原反应的是( ) A.化合反应 B.分解反应 C.置换反应 D.复分解反应 2．下列反应中，属于非氧化还原反应的是 ( ) A.3CuS＋8HNO3＝3Cu(NO3)2＋2NO↑＋3S↓＋4H2O B.3Cl2＋6KOH ＝5KCl＋KClO3＋3H2O C.3H2O2＋2KCrO2＋2KOH ＝2K2CrO4＋4H2O D.3CCl4＋K2Cr2O7＝2CrO2Cl2＋3COCl2＋2KCl （COCl2碳酰氯） 3.某元素在化学反应中由化合态变为游离态,则该元素( ) A.一定被氧化 B.一定被还原 C.既可能被氧化,也可能被还原 D.以上都不是 4.根据以下几个反应： ①Cl2+2KI ==== 2KCl+I2 ②2FeCl2+Cl2 ==== 2FeCl3 ③2FeCl3+2KI ==== 2FeCl2+2KCl+I2判断氧化性由强到弱的顺序是( ) A．Cl2＞I2＞Fe3+B．Cl2＞Fe3+＞I2 C． Fe3+＞I2＞Cl2 D．Fe3+＞I2＞Cl2 5.下列关于氧化还原反应说法正确的是（） A．肯定一种元素被氧化，另一种元素被还原 B．某元素从化合态变成游离态，该元素一定被还原 C．在反应中不一定所有元素的化合价都发生变化 D．在氧化还原反应中非金属单质一定是氧化剂 6.下列变化过程属于还原反应的是( ) A.HCl→MgCl2 B.Na→Na+ C.CO→CO2 D. Fe3+→Fe 7.下列叙述正确的是( ) A.氧化还原反应的本质是化合价发生变化 B.有单质产生的分解反应一定是氧化还原反应 C.氧化剂在同一反应中既可以是反应物,也可以是生成物 D.还原剂在反应中发生还原反应 8.下列变化需要加入氧化剂的是( )

重要的氧化剂和还原剂

重要的氧化剂和还原剂 [重要知识点] 1．熟悉常见的氧化剂和还原剂。 2．重要的氧化剂和还原剂的常见反应。 3．熟练使用单线桥分析氧化还原反应及电子转移情况。 [知识点精析] 一．化学反应的分类 二、重要的氧化剂和还原剂 1．氧化还原反应的基本概念 氧化还原反应从化合价的角度来说是指有元素化合价升降的化学反应；从本质上来看则是指有电子转移（得失或偏移）的反应。涉及氧化剂、还原剂、氧化性、还原性、氧化产物、还原产物等概念。 （1）氧化剂、还原剂 氧化剂是指在反应中得到电子（或电子对偏向）的反应物，表现为反应后所含某些元素化合价降低。氧化剂具有氧化性，在反应中本身被还原，其生成物叫还原产物。 还原剂是指在反应中失去电子（或电子对偏离）的反应物，表现为反应后所含某些元素化合价升高，还原剂具有还原性，反应中本身被氧化，生成物是氧化产物。 如下图所示：

（2）氧化剂和还原剂是性质相反的物质 在氧化还原反应中，还原剂把电子转移给氧化剂，即还原剂是电子的给予体，氧化剂是电子的接受体。 如下图所示： （3）氧化还原反应中各概念间的关系 2．氧化还原反应的判断和分析 （1）氧化还原反应的判断 判断一个化学反应是否为氧化还原反应，常根据反应中有无元素的化合价变化（有升有降）来判断。 判断一个反应是否为氧化还原反应的技巧： ①当有单质参加反应，或有单质生成时可认为该反应一定是氧化还原反应(但同素异形体间的转化除外，如白磷变红磷就不是氧化还原反应)。 ②有机物发生的反应，当分子中引入氧或失去氢被氧化，反之分子中失去氧或得到氢被还原。 （2）氧化还原反应的分析

在氧化还原反应化学方程式里，除了可用箭头表明同一元素原子的电子转移情况外(即：双线桥法)，还可以用箭头表示不同原子的电子转移情况(称为“单线桥法”)。 用箭头表明同一元素原子的电子转移情况即大家熟悉的“双线桥”。如： 用箭头表示不同原子的电子转移情况——“单线桥”。如： 更好地体现了氧化剂和还原剂在反应中的电子转移的关系。再如： ①单线桥分析氧化还原反应可简单表示为 ②反应中电子转移总数即为还原剂给出的电子总数，也是氧化剂接受的电子总数。 ③在单线桥中不写“得”或“失”。 3．常见的氧化剂、还原剂 （1）物质在反应中是作为氧化剂还是作为还原剂，主要取决于元素的化合价。 ①元素处于最高价时，它的原子只能得到电子，因此该元素只能作氧化剂，如、。 ②元素处于中间价态时，它的原子随反应条件不同，既能得电子，又能失电子，因此该元素 既能作氧化剂，又能作还原剂，如和。

氧化还原反应第三课时

氧化还原反应（第三课时） 教学目标概览 （一）知识目标 1、使学生了解氧化剂和还原剂。 2、初步掌握氧化性、还原性及其强弱的判断 （二）能力目标 培养学生的观察、思维能力及形成规律性的认识能力。（三）情感目标 对学生进行对立统一和透过现象看本质的辩证唯物主义 观点的教育。激发创造意识，培养严谨求实的优良品质。重点与难点：氧化性、还原性及其强弱的判断 教学方法：设疑、讨论、讲解、练习 教学过程： [复习引入]1、氧化还原反应的实质是什么？特征是什么？2．判断下列反应是否属于氧化还原反应；是氧化还原反应的标出化合价变化，指出氧化剂、还原剂；氧化产物，还原产物。 ①PCl（稀）＝3Cu（NO 3．用双线桥标出电子得失，指出氧化剂、还原剂；哪种物质被氧化，哪种物质被还原？①2Na＋ClO [板书]四、氧化剂和还原剂、氧化产物和还原产物（建议稍作拓展）

1、常见的氧化剂： （1）活泼的非金属单质：O等； （2）含高价金属阳离子的化合物：FeCl等 （3）含某些较高化合价元素的化合物：浓H等。 2、常见的还原剂： （1）活泼或较活泼的金属：K、Ca、Na、Al、Mg、Zn等；（2）含低价金属阳离子的化合物：FeCl等； （3）某些非金属单质：C、H等； （4）含有较低化合价元素的化合物：HCl、HS、KI等。3、在可变元素的化合价的化合物中，具有中间价态的 物质既可作氧化剂，又可作还原剂，如：Cl等；学习中 应注意：氧化剂和还原剂的确定要以实际反应为依据， 是相对而言的，同一物质在不同条件下，可以作还原剂，也可以作氧化剂。因此对规律性的知识既不能生搬硬套，也不能死记硬背，灵活掌握知识，以辩证的观点去看待 问题、解决问题。 4、氧化性、还原性及其强弱的判断 （1）依据元素化合价判断 最高价——只有氧化性 最低价——只有还原性 中间价——既有氧化性又有还原性 [练习]具有还原的离子是（）

氧化还原反应专题1

氧化还原反应专题 一、概念 1．下列关于化学反应类型的叙述中，正确的是（ A、凡是生成盐和水的反应都是中和反应 B、复分解反应一定没有单质参加 C、生成一种单质和一种化合物的反应一定是置换反应 D、分解反应一定不是氧化还原反应 2．下列反应不属于四种基本反应类型，但属于氧化还原反应的是（）A．Fe+CuSO4=FeSO4+Cu B．3CO+Fe2O 3高温2Fe+3CO2 C．AgNO3+NaCl=AgCl↓+NaNO3 D．2KMnO 4△ K2MnO4+MnO2+O2↑ 3．下列反应中，不属于氧化还原反应的是（） A．C + O 2CO2B．CH4 + 2O2CO2+ 2H2O C．CaO + H2O = Ca(OH)2 D ．CuO + H2Cu + H2O 4．下列叙述中正确的是（） A．阳离子只有氧化性，阴离子只有还原性B．含氧酸可作氧化剂而无氧酸则不能C．失电子难的原子获得电子的能力就强 D．氯气分子可作氧化剂，但也可被其他氧化剂所氧化 5．下列反应中不是氧化还原反应的是（） A．2KMnO4+16HCl(浓)=2KCl+2MnCl2+5Cl2↑+8H2O B.2NaHCO3Na2CO3+H2O+CO2↑ C. Cl2+SO2+2H2O = H2SO4+2HCl D.2Na+2H2O = 2NaOH + H2↑ 6．下列应用不涉及氧化还原反应的是（） A．实验室在硫酸亚铁中加少量铁粉B．医药上用小苏打治辽胃酸过多 C．工业上利用黄铁矿炼铁D．Na2O2用作呼吸面具的供氧剂 7．下列类型的反应，一定发生电子转移的是（） A. 化合反应 B. 分解反应 C. 置换反应 D. 复分解反应 8．制备单质硅的主要化学反应如下 ①SiO2+2C i+2CO↑ ②Si+2Cl2 SiCl4③SiCl4+2H2Si+4HCl 下列对上述三个反应的叙述中，错误 ．．的是（） A．①③为置换反应B．①②③均为氧化还原反应 C．三个反应的反应物中硅元素均被氧化 D．①是工业上制粗硅的反应，②③是粗硅提纯的反应9．利用盐酸具有氧化性的反应是（） A、与NH3反应制NH4Cl B、除去铜粉中的铁粉 C、与MnO2反应制Cl2 D、除去钢铁表面的铁锈 10．氧化还原反应中，水的作用可以是氧化剂、还原剂、既是氧化剂又是还原剂、既非氧化剂又非还原剂等。下列反应与Br2+SO2+2H2O=H2SO4+2HBr相比较，水的作用不相同 ．．．的是（） A．2Na2O2+2H2O=4NaOH+O2↑ B．2Al+2NaOH+2H2O=2NaAlO2+3H2↑ C．3NO2+2H2O=3HNO3+NO D．4Fe(OH)2+O2+2H2O=4Fe(OH)3 11．吸入人体內的氧有2%转化为氧化性极强的“活性氧”，它能加速人体衰老，被称为“生命杀手”，服用含硒元素（Se）的化合物亚硒酸钠（Na2SeO3），能消除人体內的活性氧，由此推断Na2SeO3的作用是（） A.作还原剂 B.作氧化剂 C.既作氧化剂又作还原剂 D.既不作氧化剂又不作还原剂12．下列反应中，属于氧化还原反应的是（） A．CuO+H2SO4= CuSO4+H2O B．FeC13+3NaOH=Fe(OH)3↓+3NaCl C ．Fe+2FeC13=3FeC12D．2Al(OH)3A12O3+3H2O 13．氧化还原反应与四种基本类型反应的关系如图所示，则下列化学反应属于阴影部分的是（） A．Cl2+2KBr==Br2+2KCl B．2NaHCO3 Na2CO3+H2O+CO2↑ C．4Fe(OH)2+O2+2H2O==4Fe(OH)3 D．2Na2O2+2CO2==2Na2CO3+O2 14．下列做法中用到物质氧化性的是（） A．明矾净化水B．纯碱除去油污C．臭氧消毒餐具D．食醋清洗水垢15．下列各组物质相互作用时，其中水既不作氧化剂，又不作还原剂，而反应仍属于氧化还原反应的是（） A．氟与水反应B．Na与水反应C．铝与强碱液作用D．过氧化钠与水反应16．氰氨基化钙是一种重要的化工原料，制备CaCN2的化学方程式为CaCO3＋2HCN===CaCN2＋CO↑＋H2↑＋CO2↑。在该反应中( ) A．氢元素被氧化，碳元素被还原B．HCN是氧化剂 C．CaCN2是氧化产物，H2为还原产物D．CO为氧化产物，H2为还原产物 17．相等物质的量的KClO3分别发生下述反应：①有MnO2催化剂存在时，受热分解得

钼

钼 创建时间：2008-08-02 钼(molybdenum) 元素周期表第五周期ⅥB族元素，稀有高熔点金属。元素符号Mo，原子序数42，相对原子质量95．94。致密块状金属钼呈银灰色。 简史1778年瑞典化学家舍勒(C．w．Scheele)用硝酸分解辉钼矿发现的一种新元素，以希腊文Molyb—dos(意为铅)命名。1782年瑞典化学家耶尔姆(P．J．Hjelm)首先用碳还原钼氧化物的方法制得金属钼。较纯的钼是在19世纪初用氢还原钼酸得到的。钼在它被发现前就为人们所利用。早在14世纪日本人就用含钼的钢制造马刀。在16世纪辉钼矿被误认为是变态石墨而用来制造铅笔芯。在19世纪末，发现将钼加入钢中对钢性质有良好的影响。1900年熔炼钼铁的方法研究成功。1910年发现含钼的炮钢有特殊的性能而大量生产钼钢。此后，在工业上才开始使用某些钼化合物，如作磷试剂的钼酸铵，颜料用的钼蓝等；钼成为各种耐热和防腐结构钢的重要成分，也是镍和铬合金的重要添加剂。1909～1910年金属钼开始应用于电子工业。金属钼的工业生产大约和钨的工业生产开始于同一年代，当时人们已掌握了用以生产这两种致密金属的粉末冶金方法。从发现钼至今已有200多年的历史，而钼真正用于炼钢仅1O多年。随着钼应用范围不断扩大，当今的世界钼工业已具相当规模，并发展成一个独立、完整的工业体系。 中国从1940年开始钼矿开采和选矿的生产。中华人民共和国成立后，中国的钼生产和科研得到较快发展。50年代中国相继建成了钼冶炼和钼铁生产厂。50年代末，开始用粉末冶金法生产钼制品，以后又用熔炼锭料生产钼制品。中国现阶段已形成了从矿山开采、冶炼到加工较完整的钼工业生产体系，能生产出国内所需的各种钼制品合金和含钼钢。90年代生产规模已达到年产钼近1．5万t的水平，约有一半产品用于出口，在国际市场上已占有引人注目的地位。 性质钼和钨的性质十分相似，具有高温强度好、硬度高、密度大、抗腐蚀能力强、热膨胀系数小、良好的导电和导热等重要特性，因而是一种用途较广泛的金属。钼mu物理性质自然界中存在七种钼稳定同位素，其质量数从92到100。其中丰度最大的是Mo，占24．14％。金属钼为体心立方晶体结构，具有熔点高、沸点高、导电性较好、电子逸出功较小的性能。钼的主要物理性质列于表1。

三氧化钼

三氧化钼 Molybdenum trioxide 性状：三氧化钼［MoO 3 ］，别名：氧化钼。无色或黄白色粉末，斜方晶系结晶。极微溶于水，溶于酸、碱和氨水溶液。 执行标准：Q/320583W&M209－2004 CA登记号：1313-27-5 质量标准：三氧化钼［MoO 3 ］≥98% 用途：用作石油工业的催化剂，也用于制金属钼、瓷釉颜料和药物等。包装：铁桶、纸板桶、纸袋或有色塑料桶，内衬双层聚乙烯袋，25Kg ，50kg 。 MoO3-2 标准目录浏览 工业钼酸钠 Industrial Sodium Molybdate 性状：钼酸钠［Na 2MoO 4 ·2H 2 O］白色或无色结晶粉末，易溶于水。 执行标准：Q/320583W&M204－2004 CA登记号：7631-95-0

质量标准：钼酸钠［Na 2MoO 4·2H 2O ］≥98% 用途：用于染料、颜料或催化剂的原料，也可作防腐蚀剂的制造。 包装：铁桶、纸板桶、纸袋或有色塑料桶，内衬双层聚乙烯袋，50kg 。 工业钼酸铵 Industrial Ammoinum Molybdate 性 状：工业钼酸铵［（NH 4）2Mo 4O 13·2H 2O ］，为白色或微黄色粉末，在水、普通矿物酸中微 溶，易溶于碱，不溶于醇和丙酮。 执行标准：Q/320583W&M205－2004 质量标准：工业钼酸铵［（NH 4）2Mo 4O 13·2H 2O ］≥98% 用途：主要用于染料、颜料，是制取钼粉、微量元素肥料、制造陶瓷颜料及其它钼化合物的原料。 包装：铁桶、纸袋，内衬双层聚乙烯袋，50kg 。 三 氧 化 钨 Tungsten Trioxide 性 状：三氧化钨［WO 3］别名：钨酸酐。淡黄色粉末。不溶于水和一般无机酸， 溶于热碱液， 微溶于氢氟酸。 执行标准：Q/320583W&M109－2004

氧化还原反应专题.

氧化还原反应专题 [氧化还原知识网络] 一、化学反应的类型 1．化学反应基本类型（依据反应物、生成物的类别和种类分类） 化学反应 2．氧化还原反应和非氧化还原反应（依据反应物有无电子转移或物质的相关元素在反应前后有无化合价改变分类） 化学反应 3．其它分类法 a．依据反应的热效应分为：吸热反应，放热反应。 b．依据反应进行的程度分为：可逆反应，非可逆反应。

c.依据反应中有无离子参与分为：离子反应，分子反应。 4．氧化还原反应与基本反应类型的关系 ⑴置换反应都是氧化还原反应； ⑵复分解反应都是非氧化还原反应； ⑶化合反应和分解反应可能为氧化还原反应； 它们的关系可用下图表示： 说明： ⑴有单质参与的化合反应或分解反应多数为氧化还原反应，但不一定是氧化还原。 如： ①4P（红）＝P4为化合反应，但为非氧化还原反应； ②2O3＝3O2有单质生成但为非氧化还原； ⑵没有单质参与的化合反应或分解反应也可能是氧化还原反应。 如： ①NH4NO3的分解，随条件不同，产物也不同，可能生成NO2、H2O等为氧化还原反应，但没有单质参与； ②Na2O2与MnO2化合可以生成Na2MnO4也是氧化还原反应，但没有单质参与。 二、氧化还原反应 1、特征：

反应前后元素的化合价发生改变。 2、实质： 有电子转移（电子的得失或共用电子对的偏移）。 3、氧化还原反应概念 ①氧化与还原（指反应过程） ②氧化剂与原还剂（指反应物质） ③氧化性与还原性（指物质能获得电子或能失去电子的性质） 注： 物质的氧化性（或还原性）的强弱，指的是得（或失）电子的难易，不是指得（失）电子的多少。 ④氧化产物与还原产物（指生成物） 4、氧化还原反应概念间的关系。 5、氧化还原反应中电子转移的表示方法 ⑴双线桥法――表明了反应前后某种元素化合价的变化情况 ①用两条带箭头的线由反应物指向生成物，且对准同种元素。 ②要标明“得”“失”电子，且得失电子总数相等。 ③箭头不代表电子转移的方向，而是指某元素从反应到产物时价态的变化。

重要的氧化剂和还原剂

重要的氧化剂和还原剂 重点、难点 1. 熟悉常见的氧化剂和还原剂。 2. 重要的氧化剂和还原剂的常见反应。 3. 熟练使用单线桥分析氧化还原反应及电子转移情况。 具体内容 （一）重要的氧化剂和还原剂 1. 氧化还原反应的基本概念 氧化还原反应从化合价的角度来说是指有元素化合价升降的化学反应；从本质上来看则是指有电子转移（得失或偏移）的反应。涉及氧化剂、还原剂、氧化性、还原性等概念。 （1）氧化剂、还原剂的概念及它们在氧化还原反应中关系，及其本质变化及外在表现。 氧化剂是指在反应中得到电子（或电子对偏向）的物质，表现为反应后所含某些元素化合价降低。氧化剂具有氧化性，在反应中本身被还原，其生成物叫还原产物。 还原剂是指在反应中失去电子（或电子对偏离）的物质，表现为反应后所含某些元素化合价升高，还原剂具有还原性，在反应中本身被氧化，其生成物是氧化产物。 （2）氧化剂和还原剂是性质相反的物质 在氧化还原反应中，还原剂把电子转移给氧化剂，即还原剂是电子的给予体，氧化性是电子的接受体。 （3）氧化还原反应中各概念间的关系 2. 氧化还原反应的判断和分析 （1）氧化还原反应的判断 判断一个化学反应是否为氧化还原反应，常根据反应中有无元素的化合价变化（有升有降）来判断。 判断一个反应是否为氧化还原反应的技巧： ①当有单质参与反应，或有单质生成时可认为该反应一定是氧化还原反应。 ②有机物发生的反应，当分子中引入氧或失去氢可认为被氧化，反之分子中失去氧或得到氢可认为被还原。

（2）氧化还原反应的分析 在氧化还原反应化学方程式里，除了可用箭头表明同一元素原子的电子转移情况外，还可以用箭头表示不同原子的电子转移情况。 用箭头表明同一元素原子的电子转移情况即大家熟悉的“双线桥”。如： 用箭头表示不同原子的电子转移情况——“单线桥”。如： 更好地体现了氧化剂和还原剂在反应中的关系。 再如： ①单线桥分析氧化还原反应可简单表示为 ②反应中电子转移总数等于还原剂给出的电子总数，也必然等于氧化剂接受的电子总数。 3. 常见的氧化剂、还原剂 （1）物质在反应中是作为氧化剂还是作为还原剂，主要取决于元素的化合价。 ①元素处于最高价时，它的原子只能得到电子，因此该元素只能作氧化剂，如、。 ②元素处于中间价态时，它的原子随反应条件不同，既能得电子，又能失电子，因此该元素既能作氧化剂，又能作还原剂，如和。 ③元素处于最低价时，它的原子则只能失去电子，因此该元素只能作还原剂，如。 （2）重要的氧化剂 ①活泼非金属单质，如F2、Cl2、Br2、O2等。 ②元素处于高价时的氧化物、含氧酸、盐等，如MnO2，NO2；浓H2SO4，HNO3；KMnO4，KClO3，FeCl3等。 ③过氧化物，如Na2O2，H2O2等。 （3）重要的还原剂 ①活泼的金属单质，如Na，K，Zn，Fe等。 ②某些非金属单质，如H2，C，Si等。 ③元素处于低化合价时的氧化物，如CO，SO2等。 ④元素处于低化合价时的酸，如HCl（浓），HBr，HI，H2S等。

高中化学 第二章 第三节 氧化还原反应(第3课时)学案 新人教版必修1

氧化还原反应（第3课时） 【学习目标】 1. 掌握物质氧化性、还原性强弱的比较方法。 2. 掌握氧化还原反应的配平和简单计算的方法。 【学习过程】 1. 氧化还原反应的基本规律： （1）守恒律：化合价有升必有降，电子有得必有失。对于一个氧化还原反应，化合价升高总数与降低总数相等，失电子总数与得电子总数相等。 （2）价态规律：①元素的最高价态在反应中只能得电子而不能失电子，所以元素处于最高价态时只有氧化性而没有还原性，即只能做氧化剂，不能做还原剂。如：Fe3+、H+、Al3+、浓H2SO4中S(+6)、HNO3中的 N(+5)等。②元素的最低价态在反应中只能失去电子而不能得到电子，所以元素处于最低价态时只有还原性而没有氧化性，即只能做还原剂，不能做氧化剂。如：Fe、Cu、S2－、I－、Br－等。③元素的最高价态与它的最低价态之间的中间价态，在反应中既能失电子，本身被氧化，又能得电子，本身被还原，所以处于中间价态的元素既有氧化性又有还原性。它跟强氧化剂反应表现还原性，跟强还原剂反应表现氧化性。如：S、S(+4)、Fe2+、NO等。 （3）不交叉规律：同一反应中同种元素不同价态的原子间发生氧化还原反应，其结果是两种价态只能相互靠拢，不能交叉。 （4）转化规律：氧化还原反应中，同种元素不同价态之间若发生反应，元素的化合价只靠近而不交叉，例如：KClO3+6HCl=KCl+3Cl2↑+ 3H2O反应中， KClO3中+5的氯元素不会转化为KCl中－1价的氯元素。再如：H2S+H2SO4（浓）=S↓+SO2+2H2O。同种元素，相邻价态间不发生氧化还原反应，例如浓硫酸与二氧化硫不会发生反应。 （5）强弱规律：较强氧化性的氧化剂跟较强还原性的还原剂反应，生成弱还原性的还原产物和弱氧化性的氧化产物。 （6）难易规律：越易失电子的物质，失电子后就越难得电子，越易得电子的物质，得电子后就越难失电子；一种氧化剂同时和几种还原剂相遇时，还原性最强的优先发生反应；同理，一种还原剂遇多种氧化剂时，氧化性最强的优先发生反应。 2.氧化性、还原性强弱的判断方法： （1）根据元素的化合价：物质中元素具有最高价态，该元素只有氧化性；物质中元素具有最低价态，该元素只有还原性；物质中元素具有中间价态，该元素既有氧化性又有还原性。对于同一种元素，价态越高，其氧化性就越强；价态越低，其还原性就越强。 （2）根据氧化还原反应方程式：在同一氧化还原反应中，氧化性：氧化剂>氧化产物；还原性：还原剂>还原产物。氧化剂的氧化性越强，则其对应的还原产物的还原性就越弱；还

高考化学第三节氧化剂和还原剂专题1

高考化学第三节氧化剂和还原剂专题1 2020.03 1,造纸工业常用Cl2漂白纸浆。漂白后的纸浆要用NaHSO3除去残留的Cl2，其反应为： Cl2 + NaHSO3 + H2O = NaCl+ HCl + H2SO4，在这个反应中，氧化产物与还原产物的 物质的量之比（） A． 1:1 B． 1:2 C． 2:1 D． 2:3 2,下列变化中，必须加入氧化剂才能发生的是 ( ) A．SO2→S B．SO32-→SO2 C．HCO32- →CO32- D．I-→I2 3,单质X和Y相互反应生成X2+Y2-，现有下列叙述：①X被氧化,②X是氧化剂,③X具有氧化性,④Y2-是还原产物,⑤Y2-具有还原性,⑥X2+具有氧化性, ⑦Y的氧化性比X2+氧化性强。其中正确的是 A.①②③④ B.①④⑤⑥⑦ C.②③④ D.①③④⑤ 4,对于司机酒后驾车，可取其呼出的气体进行检验而查出，所利用的化学方程式如下：2 CrO3(红色)＋3C2H5OH＋3H2SO4＝Cr2(SO4)3(绿色)＋ 3CH3CHO＋6H2O,该反应被检测的气体是；上述反应中的氧化剂是，还原剂是。 5,吸进人体内的氧有2%转化为氧化性极强的活性氧，这些活性氧能加速人体衰老，被称为“生命杀手”，科学家尝试用Na2SeO3消除人体内活性氧，则Na2SeO3的作用是( ) A．氧化剂 B．还原剂

C．既是氧化剂又是还原剂 D．以上均不是 6,下列化学反应中，属于氧化还原反应的是 A.Na2CO3＋2HCl＝2NaCl＋CO2↑＋H2O B.CaO+H2O＝Ca(OH)2 C.CaCO3CaO+CO2↑ D.2CO +O2 2CO2 7,下列变化过程，属于还原反应的是( ) A． B． C． D． 8,在3BrF3+5H2O=HBrO3+Br2+9HF+O2↑反应中，有9g水被消耗时，被还原的BrF3的质量为 A.13.7g B.27.4g C.41.1g D.123.3g 9,实验室里常利用反应：3Cu+8HNO 33Cu(NO3)２＋2NO↑+4H2O来制取NO，当有6.4gCu参加反应时，计算： （1）能生成多少升NO（标准状况下）? （2）消耗多少摩HNO3? （3）被还原的HNO3的物质的量? 10,过氧化氢H2O2，俗名双氧水，医疗上利用它的杀菌消毒作用来清洗伤口。将双氧水加入经酸化的高锰酸钾溶液中，溶液的紫红色消失，此时双氧水表现出性。 11,随着人们生活节奏的加快，方便的小包装食品已被广泛接受。为了延长食品的保质期，防止食品受潮及富脂食品氧化变质，在包装袋中应放入的化学物质是( ) A．无水硫酸铜、蔗糖 B．硅胶、硫酸亚铁