
Description
Numeroustechniqueshavebeendevelopedtoprepareimmunoliposomesbasedonthenucleophilicreactivityoffreeaminegroupsofproteinsorpeptides.However,themostcommon,versatileandstraightforwardactivationchemistryforcreatingreactiveacylatingreagentsandlabelingpeptides/proteinsistoformNHSesterwithprimaryamines.AsinglestepnucleophilicsubstitutionreactionbetweenNHSesterderivativeandalphaaminesattheNterminalorthebetaaminesoflysinesidechainsleadstotheformationofastableamidebond.
N-Hydroxysuccinimide(NHS)estersofDSPE-PEG-NHSliposomesreactwiththeprimaryaminegroupsonthepeptides,proteins,antibodiesorotherfunctionalligandsfortargeteddrugdeliveryapplications.ThenucleophilicattackoftheaminegroupsontheNHS-activatedcarbonylgroupoftheDSPE-PEG-NHSresultsintheeliminationoftheNHSgroupandformationofamidelinkage.
Immunodox®-NHSisaPEGylatedproduct.Forotheraminereactive(PEGylatedandnon-PEGyalatedproducts)andalsoImmunodox®productssuitableforothertypesconjugationmethodsseehere.

FORMULATIONINFORMATION
Immunodox®-NHS(PEGylated)(Post-insertion)
PostInsertionKit(3Vials) | Specification |
---|---|
Vial1 | PreformedDoxorubicinLiposomescomposedofHSPCandCholesterol(60:40molarratio) |
Vial2 | DSPE-PEG(2000)-NHSlipid(reactivePEGylatedlipid)inpowderform |
Vial3 | DSPE-PEG(2000)lipid(non-reactivePEGylatedlipid)inpowderform |
LipidCompositionforVial1* | Concentration(mg/ml) | Concentration(mM) | MolarRatioPercentage |
---|---|---|---|
HydrogenatedSoyPC | 11.5 | 14.66 | 60 |
Cholesterol | 3.83 | 9.9 | 40 |
Total | 15.33mg/ml | 24.56mM | 100 |
*Forthe5-mlkit,thevolumeofvial1is4ml.1mlofmicellesolutionthatareformedusingvials2and3willbeaddedtothisvialtomakethefinalvolumeof5mlinthefinalproduct.Forthe2-mlkit,thevolumeofvial1is1.6ml.0.4mlofmicellesolutionthatisformedusingvials2and3willbeaddedtothisvialtomakethefinalvolumeof2mlinthefinalproduct. |
Buffers,LiposomeSizeandEncapsulatedDrugConcentrationforVial1 | Specification |
---|---|
InsideBuffer | AmmoniumSulfate |
OutsideBuffer | PhosphateBufferedSaline |
pH | 7.4 |
LiposomeSize | 100nm |
EncapsulatedDoxorubicin | 2mg/ml(3.45mM) |
Vial2* | Specification |
---|---|
DSPE-PEG(2000)-NHSLipid | ThisvialcontainsreactiveDSPE-PEG(2000)-NHSlipidinpowderform.Thislipidisconjugatedtoareactiveprotein,peptideorligandcontainingamineandthenmixedwithnon-reactiveDSPE-PEG(2000)lipidinaqueoussolutiontoformmicelles.ThePEGylatedlipidmicellesareincubatedwithpreformedliposomesinvial1andPEGlipidswillpost-insertthemselvesintotheliposomes.![]() |
*TheamountofthepowderedPEG(2000)-NHSlipidforthe2-mlkitis1.34mgandforthe5-mlkitis3.34mg. |
Vial3* | Specification |
---|---|
DSPE-PEG(2000)Lipid | Thisvialcontainsnon-reactiveDSPE-PEG(2000)lipidinpowderform.ThislipidinmixedwithDSPE-PEG(2000)-NHSlipidwhichisalreadyconjugatedtoaligand(protein,peptide,etc.)inaqueoussolutiontoformmicelles.ThePEGylatedlipidmicellesareincubatedwithpreformedliposomesinvial1andPEGlipidswillpost-insertthemselvesintotheliposomes.![]() |
*TheamountofthepowderedPEG(2000)-DSPElipidforthe2-mlkitis5mgandforthe5-mlkitis12.5mg. |
ConjugationProtocol
MaterialsandEquipment
The3-vialpost-insertionkitcontainspreformedliposomes(vial1),non-reactivePEGylatedlipidinpowderform(vial2)andDSPE-PEG(2000)-NHSlipidinpowderform(vial3). Inordertousethepost-insertionkit,youwillneed:
- Laboratoryvortexmixerisrecommendedtohave.
- Laboratorymagneticstirrerisneededfordialysis.
- Twosmall10mlroundbottomflasksortwosmallglassvials.
- Arotaryevaporator. Weunderstandthatmanylabsmightnothavearotovap.Alternatively,youcanuseanitrogentankconnectedtoathinhoseforcreatingastreamofnitrogenflowtodrythelipidandmakeathinfilm.
- Asmallamountofasolventsuchachloroformormethylenechloride(youwillonlyneedafewmilliliters).
- Phosphatebufferedsaline(PBS).
- ASonicator.Itisbettertohaveabathsonicator.Ifyoudonot,thatisfine.Youstillcanfollowtheprotocol.Youmayalsouseavortexinsteadofthesonicatorforagitationofthesolutionaswell.
- Float-A-Lyzer®withaproperMWCOthateasilyallowsthecleanupofyourliposomeconjugatedligandfromfreeandnon-conjugatedprotein,peptideorantibody.YouneedtomakesurethattheMWCOisbelow1,000,000dalton.At1,000,000daltontheporesizeonthedialysismembranegetscloseto100nmandthereforeyourliposomescanbedialyzedout.Youcannotusedialysiscassettesblindly.Pleaseunderstandthetechniquebeforeusingeitherspincolumnordialysiscassette.IfyoudonotusethecorrectMWCOyoucanloseyourentireprep.ForthisprotocolwerecommendMWCOof300,000dalton.
PreparationMethod
- Thepost-insertionkitscomeintwosizes;2mland5ml.Forthe2mlkitsize,dissolvethecontentofvial3in100µlofchloroformormethylenechloride.Forthe5mlkitsize,thecontentofvial3shouldbedissolvedin250µlofchloroformormethylenechloride.Transferthesolutiontoa10mlroundbottomflask.Drythechloroformusingarotaryevaporatororunderastreamofnitrogenandmakeadriedlipidfilm.
- Forthe2mlkit,add100µlofPBSbuffertothedriedlipidfilm.Forthe5mlkit,theamountoftheaddedbufferis250µl.Itispreferredtosonicatethehydratedlipidfilmusingabathsonicatorandsonicatethemicellesolutionfor5minutes.IfyoudonothaveabathsonicatorthenhydratethedriedlipidfilmwithPBSforatleast1hourandconstantlyrotatethesolutionintheroundbottomflaskusingarotavap(notconnectedtovacuum)orbyhandtomakesurethatallthedriedlipidonthewalloftheroundbottomflaskwillgotothesolutionandformmicelles.Alternatively,youcanuseavortextoagitatethesolution.Thegoalistohaveallthedriedlipidonthewalloftheroundbottomglasstogothemicellesolution.CoverthemouthoftheroundbottomflaskwithParafilm.Refrigeratethemicellesolutionofnon-reactivePEGlipidsuntilitisreadytobemixedwithmicellesformedinstep4.
- For2mlpost-insertionkit,theamountofDSPE-PEG-NHSis1.34mg(0.22µmol)andfor5mlofpost-insertionkittheamountofDSPE-PEG-NHSis3.34mg(0.55µmol).Forthe2mlkitsize,dissolvethecontentofvial2in100µlofchloroformormethylenechloride.Forthe5mlkitsize,thecontentofvial2shouldbedissolvedin250µlofchloroformormethylenechloride.Transferthesolutiontoa10mlroundbottomflask.Drythechloroformusingarotaryevaporatororunderastreamofnitrogen.
- Addthewater-solubleprotein,peptideorligandat1:2molarratioofligandtodriedfilmofDSPE-PEG-NHS.For2mlkitadd300µlofwater-solublesolutionofproteinofligandinPBS(pH7.4)tothedriedlipidfilmandfor5mlkitadd750ulofwater-solublesolutionofproteinofligandinPBS(pH7.4)tothedriedlipidfilm.Itispreferredtosonicatethehydratedlipidfilmusingabathsonicatorandsonicatethemicellesolutionfor5minutes.IfyoudonothaveabathsonicatorthenhydratethedriedlipidfilmwithPBSforatleast1hourandconstantlyrotatethesolutionintheroundbottomflaskusingarotavap(notconnectedtovacuum)orbyhandtomakesurethatallthedriedlipidonthewalloftheroundbottomflaskwillgotothesolutionandformmicelles.Alternatively,youcanuseavortextoagitatethesolution.Thegoalistohaveallthedriedlipidonthewalloftheroundbottomglasstogothemicellesolution.Thesolutionisincubatedatroomtemperaturefor6hoursandinrefrigeratorfor24hours.ThereactionispHsensitive.Readthetechnicalnotebelowformoreinformation.
- Mixthemicellesinstep2tothemicellesinstep4.Thetotalvolumeofmicellesfor2mlkitshouldbe400µlandfor5mlkitshouldbe1000µl.
- Toconductpost-insertion,themicellardispersionisthenco-incubatedwithpreformedplainliposomesat60℃for30min.
- Removethenon-conjugatedprotein,peptideorantibodyfromtheimmunoliposomesbydialysis.Wepreferdialysistosizeexclusioncolumns.Dialysisisamuchslowerprocessbuttherewillbeminimumlossofimmunoliposomesaftertheprepiscleanedfromnon-conjugatedprotein/peptide/ligand.Spincolumnsaremuchfaster;however,youcaneasilyloseover50%oftheliposomesonthespincolumn.WerecommendusingFloat-A-Lyzer® dialysiscassettefromSpectrumLabs.YouwillneedtochooseacassettewithproperMWCOdependingontheMWofyourprotein,peptide,antibodyorantibodyfragment.NOTE:Ifyoudecidetouseadialysiscassette,youwillneedtomakesurethattheMWCOisbelow1,000,000dalton.At1,000,000dalton,theporesizeonthedialysismembranegetscloseto100nmandtherefore,yourliposomescanbedialyzedout.Youcannotusedialysiscassettesandspincolumnsblindly.Theycomeinvarioussizesandyouneedtochoosethecorrectsizewisely.Dialyzetheimmunoliposomesolutionin1literofPBSatpH7.4for8hours.Changethedialysisbufferwithafresh1literofPBSandletisdialyzeforanother8hours.Afterthisstep,yourcleanedupimmunoliposomeisreadytobeused.
LiposomeParticleCalculator
Immunodox®liposomesareunilamellarandsizedto100nm.Themolarconcentrationofliposomeis24.56mM.Byhaving liposomediameter(nm)andlipidconcentration(µM),youcancalculatethetotalnumberofthelipidsinoneliposomeandthenumberoftheliposomesinonemilliliteroftheliposomesolution.Tousethecalculatorclick here.
TechnicalNotes
- Doxorubicinisafluorescentmoleculewithλex470nmandλem585nm.Ifyouareusingafluorescenttagonyourantibodyorligand,thenyouneedtomakesurethattheywillnotinterferewitheachother.
- HydrolysisofDSPE-PEG-NHSinaqueoussolutionscompeteswiththeprimaryaminereaction,resultingintheeliminationoftheNHSgroup,whichcanconsequentlydecreasethecouplingyieldpriortothereactionwiththeprotein/antibody.InordertominimizetheimpactofthehydrolysisofNHSester,useahighconcentrationofprotein/antibodytoincreasetheefficiencyofthecross-linking.
- ThereactionofNHSesterswithaminesisstronglypH-dependent:atlowpH,theaminogroupisprotonated,andnomodificationtakesplace.Athigher-than-optimalpH,hydrolysisofNHSesterisquick,andmodificationyielddiminishes.Thehalf-lifeofNHSestersatpH7and8is4-5hoursand1hour,respectively.WhilstNHSestershaveahalf-lifeofonly10minutesatpH8.6.Therefore,toavoidthehydrolysisofNHSester,DSPE-PEG-NHSlipidshouldbeusedimmediatelyforconjugationtoantibodies,proteinsorpeptidescontainingfreeamines.NHSesterreactionsareconductedincommonbuffersatpH7-8.
- PrimaryaminebufferssuchasTrisshouldNOTbeusedbecausetheycompeteforreaction;however,insomeprocedures,itisusefultoaddTrisorglycinebufferattheendofaconjugationproceduretoquench(stop)thereaction.
- IfyouareusingaligandorpeptidethatishydrophobicthenitisrecommendedtosolubilizeitinDMSOorDMFandthenaddthebuffertoit.Itisrecommendednottousemorethan5%volumeofDMSOorDMFinthesolution.DMFandDMSOarebothcompatIBLewithliposomesandtheyarealsomiscibleinwater.Otherorganicsolventsuchasethanolandchloroformarenotcompatiblewithliposomesandwillcausetheliposomestolyse.IfyouendupusingDMSOorDMFthenaftertheconjugationreactionisdone,youneedtoremoveDMSOandDMFfromtheliposomes.InordertodothatyouneedtouseadialysiscassettethatismadefromREGENERATEDCELLULOSEMEMBRANE.NOTE:NotallmembranesarecompatiblewithDMFandDMSO.WerecommendusingaSlide-A-Lyzer™MINIDialysisDevicewithMWCOof2KmadefromregeneratedcellulosemembranemanufacturedbyThermofisher.AfterDMSOorDMFisremovedyoucanuseFloat-A-Lyzer®dialysisdeviceforthefinalstepofcleaninguptheprep.
- Liposomesshouldbekeptat4°CandNEVERbefrozen.
Database
Directlinktothedatabasepageforeasynavigation:ImmunoliposomesConjugationDatabase
Appearance
Immunodox®-NHS(PEGylated)post-insertionkitcomesinthreevials:vial1isaredtranslucentliquidmadeofnanosizeunilamellarliposomeswhichdoesnotcontainanyreactiveofnon-reactivePEGylatedlipid. Usuallyduetothesmallsizeofliposomesnosettlingwilloccurinthebottomofthevial.Vial2containsreactiveDSPE-PEG(2000)-NHSlipidinwhitepowderform.Vial3containsnon-reactiveDSPE-PEG(2000)lipidinwhitepowderform.
EducationalVideo
Ordering/ShippingInformation
- Allliposomebasedformulationsareshippedonblueiceat4°Cininsulatedpackagesusingovernightshippingorinternationalexpressshipping.
- LiposomesshouldNEVERbefrozen.Icecrystalsthatforminthelipidmembranecanrupturethemembrane,changethesizeoftheliposomesandcausetheencapsulateddrugtoleakout.Liposomesinliquidformshouldalwaysbekeptintherefrigerator.
- ClientswhoorderfromoutsideoftheUnitedStatesofAmericaareresponsiblefortheirgovernmentimporttaxesandcustomspaperwork.EncapsulaNanoSciencesisNOTresponsibleforimportationfeestocountriesoutsideoftheUnitedStatesofAmerica.
- WestronglyencouragetheclientsinJapan,Korea,TaiwanandChinatoorderviaadistributor.Toughcustomsclearanceregulationsinthesecountrieswillcausedelayincustomclearanceoftheseperishableformulationsifordereddirectlythroughus.Distributorscaneasilyclearthepackagesfromcustoms.Toseethelistofthedistributorsclickhere.
- ClientsorderingfromuniversitiesandresearchinstitutesinAustraliashouldkeepinmindthattheliposomeformulationsaremadefromsyntheticmaterialandtheformulationsdonotrequirea“permittoimportquarantinematerial”.LiposomesareNOTBIOLOGicalproducts.
- Ifyouwouldlikeyourinstitute’sFedExorDHLaccounttobechargedforshipping,thenpleaseprovidetheaccountnumberatthetimeofordering.
- EncapsulaNanoScienceshasnocontroloverdelaysduetoinclementweatherorcustomsclearancedelays.YouwillreceiveaFedExorDHLtrackingnumberonceyourorderisconfirmed.ContactFedExorDHLinadvanceandmakesurethatthepaperworkforcustomsisdoneontime. AllsubsequentshippinginquiriesshouldbedirectedtoFederalExpressorDHL.
StorageandShelfLife
Storage
Immunodox®productsshouldalwaysbestoredatinthedarkat4°C,exceptwhenbroughttoroomtemperatureforbriefperiodspriortoanimaldosing.DONOTFREEZE.IfthesUSPensionisfrozen,theencapsulateddrugcanbereleasedfromtheliposomesthuslimitingitseffectiveness.Inaddition,thesizeoftheliposomeswillalsochangeuponfreezingandthawing.
ShelfLife
Immunodox®-NHSismadeondailybasis.Thebatchthatisshippedismanufacturedonthesameday.Itisadvisedtousetheproductswithin4monthsofthemanufacturingdate.
ReferencesandbackgroundreADIng
1.NaK,LeeSA,JungSH,HyunJ,ShinBC.Elastin-likepolypeptidemodifiedliposomesforenhancingcellularuptakeintotumorcells.ColloidsandSurfacesB:Biointerfaces.2012Mar1;91:130-6.
2.DaiW,FanY,ZhangH,WangX,ZhangQ,WangX.AcomprehensivestudyofiRGD-modifiedliposomeswithimprovedchemotherapeuticefficacyonB16melanoma.Drugdelivery.2015Jan2;22(1):10-20.
3.FerreiraDdosS,FariaSD,deAraújoLopesSC,TeixeiraCS,MalachiasA,Magalhães-PaniagoR,deSouzaFilhoJD,OliveiraBL,GuimarãesAR,CaravanP,FerreiraLA.Developmentofabone-targetedpH-sensitiveLiposomalformulationcontainingdoxorubicin:physicochemicalcharacterization,cytotoxicity,andbiodistributionevaluationinamousemodelofbonemetastasis.Internationaljournalofnanomedicine.2016;11:3737-51.
4.WangD,FuJ,ShiY,PengD,YuanL,HeB,DaiW,ZhangH,WangX,TianJ,ZhangQ.ThemodulationoftumorvesselpermeABIlitybythalidomideanditsimpactsondifferenttypesoftargeteddrugdeliverysystemsinasarcomamousemodel.JournalofControlledRelease.2016Sep28;238:186-96.
5.FeiW,ZhangY,HanS,TaoJ,ZhengH,WeiY,ZhuJ,LiF,WangX.RGDconjugatedliposome-hollowsilicahybridnanovehiclesfortargetedandcontrolleddeliveryofarsenictrioxideagainsthepaticcarcinoma.Internationaljournalofpharmaceutics.2017Mar15;519(1):250-62.
6.AbuchowskiA,KazoGM,VerhoestJrCR,VanEsT,KafkewitzD,NucciML,ViauAT,DavisFF.Cancertherapywithchemicallymodifiedenzymes.I.Antitumorpropertiesofpolyethyleneglycol-asparaginaseconjugates.Cancerbiochemistrybiophysics.1984Jun;7(2):175-86.
7. SartoreL,CalicetiP,SchiavonO,VeroneseFM.EnzymemodificationbyMPEGwithanaminoacidorpeptideasspacerarms.Appliedbiochemistryandbiotechnology.1991Jan1;27(1):45-54.
8. ShahinM,SoudyR,El-SikhryH,SeubertJM,KaurK,LavasanifarA.Engineeredpeptidesforthedevelopmentofactivelytumortargetedliposomalcarriersofdoxorubicin.Cancerletters.2013Jul1;334(2):284-92.
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2.加大辣根过氧化物酶标记的链霉亲和素;
我现在用商品化的试剂盒进行夹心法ELISA测定某抗体的浓度,盒子给定了4个标准品,标准品抗体浓度为70000~1000单位,测定步骤中要求对样品进行1:1000稀释后测定。
但是有的样本按照1:1000稀释后,最终OD值大于70000浓度的标准品的OD值,然后使用ELISACALC软件进行四参数拟合,超过了标准曲线的范围,就算不出来这个样品的浓度,但是如果在1000-70000之间的OD值就可以算出相应浓度。请教大神们,接下来我是否可以对样品进行1:2000,1:4000浓度稀释,算出结果后再×2、×4,算作此样品的浓度呢?还是直接给一个>70000的定性结果?或者可以有能算出来的其他软件?
Ps试剂盒中提及Dilutionlinearity(稀释线性?)为141%,这个是什么意思呢?
多谢!!
请大家帮帮忙,第一步加完抗原后必须封闭吗
目前,我用该蛋白的鼠源性单抗来包被ELISA板子,5%BSA37度封闭二小时后,洗涤四次后将板子分三个组加入抗原:其中一个组中加入的是我重组的蛋白,另一个组为用其它方法证实含该蛋白的人体内血清,最后一个组加入PBS。37度一小时后洗涤四次后每孔加入我制备的兔源性多抗。37度一小时洗涤六次后我再加入酶标记的抗兔的抗体37度40分钟后洗涤六次后TMB显色。
问题就在我显色后所有的孔都是阳性,其中以抗原为我的重组蛋白组与PBS组OD值最高,两组都可以达到1.8以上,而加入的抗原为人体血清组低,为0.6-1.0不等。
后面我优化条件,封闭液用过5%的脱脂奶粉,2%的BSA,包被的单抗浓度摸了梯度,加入的多抗也摸了梯度,酶标的抗体也摸了梯度。结果都没有改变,连趋势每次都是一样以重组蛋白组与PBS组OD最高。
今天我还试着把抗原换成其它蛋白也做出了强阳性?
请教各位高手,我的ELISA该如何往下面做了啊,是不是我的抗体本身有问题呢?
对了,我包被用的单抗是用GE公司的预装柱纯化的,很纯,在考染中是看不到一条杂带的。
ELISA双抗体夹心法(enzyme linked immunosorbent assay——sandwich technique)的原理是将特异性抗体结合到固相载体上形成固相抗体,然后和待检血清中的相应抗原结合形成免疫复合物,洗涤后再加酶标记抗体,与免疫复合物中抗原结合形成酶标抗体-抗原-固相抗体复合物,加底物显色,判断抗原含量。
生物帮有相关介绍。编码RNA http://doc.bio1000.com/show-3399.html
(2)封闭:将已包被的板用洗涤液洗涤2次,每孔加入120 μL封闭液,封闭一段时间,取出,甩干备用。
(3)竞争反应:在制备好的板中每孔加入50 μL系列浓度的标准品溶液和50 μL稀释好的酶标抗体溶液,孵育一段时间。
(4)洗板:用洗涤液洗涤5次。
(5)显色反应:每孔加入显色溶液100 μL,孵育一段时间。
(6)终止:每孔各加入终止液,在酶标仪上测定各孔的吸光值。