
Description
Numeroustechniqueshavebeendevelopedtoprepareimmunoliposomesbasedonthenucleophilicreactivityoffreeaminegroupsofproteinsorpeptides.OneofthemostpopularandcommonlyusedmethodsistocovalentlycouplefreecarboxylicgroupstoprimaryaminesthroughactivationofthecarboxylgroupswithEDC(1-ethyl-3-[3-dimethylaminopropyl]carbodiimide).EDC,whichisaso-calledzero-lengthcrosslinkingagent,reactswiththecarboxyltoformanaminereactiveintermediate(O-acylisourea).TheproducedO-acylisoureacanbeeasilydisplacedbynucleophilicattackfromtheprimaryaminogroupsinthereactionmixture.However,thisintermediateisunstableandhydrolyzedinaqueoussolutions.Inordertopreventtheintermediatehydrolysis,sulfo-NHS(N-hydroxysulfosuccinimide)isaddedtoEDCtoproduceasignificantlymorestableandmoresolubleactiveintermediate(NHSester).
Consequently,theimmunoliposomesarepreparedbyatwo-stepcouplingprocedure:first,activatingthefreecarboxylgroupofthelinkerlipidincorporatedintheliposomeswithEDCandsulfo-NHS,andthencovalentlyconjugatingtheantibodiestothelipidsthroughdisplacementofsulfo-NHSgroupsbyantibodyamines,asdepictedbelow.EDC/sulfo-NHScouplingreactionsarehighlyselectiveandhighlyefficient,andtheBIOLOGicalactivityoftheproteinorpeptideispreserved.

Immunodox®-CarboxylicAcidisaPEGylatedproduct.Forotheraminereactive(PEGylatedandnon-PEGyalatedproducts)andalsoImmunodox®productssuitableforothertypesconjugationmethodsseehere.
FormulationInformation
Immunodox®-CarboxylicAcid(PEGylated)
LipidComposition | Concentration(mg/ml) | Concentration(mM) | MolarRatioPercentage |
---|---|---|---|
Total | 15.89mg/ml | 21.58mM | 100 |
HydrogenatedSoyPC | 9.58 | 12.22 | 57 |
Cholesterol | 3.19 | 8.25 | 38 |
DSPE-PEG(2000) | 2.5 | 0.89 | 4 |
DSPE-PEG(2000)-CarboxylicAcid![]() | 0.62 | 0.22 | 1 |
Buffer,LiposomeSizeandEncapsulatedDrugConcentration | Specification |
---|---|
Buffer | PhosphateBufferedSaline |
pH | 6* |
LiposomeSize | 100nm |
EncapsulatedDoxorubicin | 2mg/ml(3.45mM) |
*InordertohavehighlyefficientactivationreactionwithEDCandSulfo-NHS,pHofPBSbufferwasadjustedto6. |
ConjugationProtocol
MaterialsandEquipment
Inordertoconjugatetheamineonyourantibody, proteinorpeptidetoImmunodox®-CarboxylicAcid(PEGylated)liposomesyouwillneed:
- EDC(1-ethyl-3-(3-dimethylaminopropyl)carbodiimidehydrochloride).Thesolutionshouldbemadefreshmomentsbeforeuse.
- Sulfo-NHS(N-hydroxysulfosuccinimide).Thesolutionshouldbemadefreshmomentsbeforeuse.
- Sephadex®spincolumn.SephadexsizeexclusionspincolumncanbeusedforseparationofliposomesformfreeEDC(MW:191.70).SinceEDCisbeingseparatedfromlargeliposomeparticlesthenanysizesofSephadex®spincolumnsuchasG-10,G-15,G-25,G50canbeused.However,keepinmindthatyouwilllosealargepercentageofyourliposomesonthespincolumn.Alternatively,insteadofremovingtheEDCbyspincolumnyoucanquenchitbyusing2-mercaptoethanol.
- 2-Mercaptoethanol.ToquenchtheunreactedEDC,2-mercaptoethanolisaddedtoformastablecomplexwiththeremainingcarbodiimide.The2-mercaptoethanolmightnotbenecessaryifyouprefertocleanupyourliposomefromfreeEDCusingaspincolumn.
- Float-A-Lyzer®withaproperMWCOthateasilyallowsthecleanupofyourliposomeconjugatedligandfromfreeandnon-conjugatedprotein,peptideorantibody.YouneedtomakesurethattheMWCOisbelow1,000,000dalton.At1,000,000dalton,theporesizeonthedialysismembranegetscloseto100nmandthereforeyourliposomescanbedialyzedout.Youcannotusedialysiscassettesblindly.Pleaseunderstandthetechniquebeforeusingeitherspincolumnordialysiscassette.IfyoudonotusethecorrectMWCO,youcanloseyourentireprep.Forthisprotocol,werecommendMWCOof300,000dalton.
PreparationMethod
Thetwo-stepprotocolincludestheactivationofcarboxylgroup-containingliposomeswithEDC/sulfo-NHS,andsubsequentconjugationwiththeaminegroupontheproteins,peptidesorantibodies:
- Inordertoactivatethecarboxylgroupsontheliposomes,EDCandsulfo-NHSshouldbeaddedtotheliposomes.ThetotallipidconcentrationinImmunodox®-CarboxylicAcid(PEGylated)is22.45mM.1%molofthelipidinliposomescontainsPEG-COOHgroupandonlyhalfofthemareexposedtotheoutsideoftheliposomes,whichisequalto0.11mMofreactiveconjugablelipid.For2mlvolumeliposomethisisequalto2.20×10-7 mol,andfor5mlvolumeliposome,thisisequalto5.50×10-7 molofPEG-COOH.Add10-foldmolarexcessofEDCand25-foldmolarexcessofsulfo-NHStoImmunodox®-CarboxylicAcid(PEGylated).Toaidinaliquotingthecorrectamountofthesereagents,theymaybequicklydissolvedinthePBSbufferatahigherconcentration,andthenapropervolumeimmediatelyPipettedintotheproteinsolutiontoobtainthepropermolarquantities. Mixwellandallowthereactiontoproceedfor15minatroomtemperature.
- Beforeaddingtheprotein,peptideorantibody,removetheexcessEDCeitherusingasizeexclusionspincolumn,suchas Sephadex®spincolumn orthroughquenchingby2-mercaptoethanolata20mMfinalconcentration.Additionof2-mercaptoethanolwillnotimpacttheliposomes.
- Dissolvetheprotein,peptideorantibodyat1-10mg/ml,dependingontheantibody,proteinorpeptide,inPBSorotheramine-free,carboxylatefreebuffer,pH7-8.
- Addtheprotein,peptideorantibodytotheEDC/Sulfo-NHSactivatedImmundox®-CarboxylicAcid(PEGylated)liposomes.Themolarratioofthereactivecarboxyllipidtoprotein,peptideorantibodyispreferedtobearound10:1.Thetotallipidconcentrationinourliposomesis22.45mM.1%molofthelipidinliposomescontainsPEG-COOHgroupandonlyhalfofthemareexposedtotheoutsideoftheliposomes,whichisequalto0.11mMofreactiveconjugablelipid.Fora2mlvolumeliposomethisisequalto2.20×10-7 molandfor5mlvolumeliposomesthisisequalof5.50×10-7 molofPEG-COOH.Youwillneedtocalculatethetotalmolofyourpeptide,proteinorligandinyoursolutionandadd1:10molarratioofligandtolipid. Mixwellandallowtoreactfor2hatroomtemperature.
- Removethenon-conjugatedprotein,peptideorantibodyfromtheimmunoliposomesbydialysis.Wepreferdialysistosizeexclusioncolumns.Dialysisisamuchslowerprocessbuttherewillbeminimumlossofimmunoliposomesaftertheprepiscleanedfromnon-conjugatedprotein/peptide/ligand.Spincolumnsaremuchfaster;however,youcaneasilyloseover50%oftheliposomesonthespincolumn.Werecommendusing Float-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.Themolarconcentrationofliposomeis21.58mM.Byhaving liposomediameter(nm)andlipidconcentration(µM),youcancalculatethetotalnumberofthelipidsinoneliposomeandthenumberoftheliposomesinonemilliliteroftheliposomesolution.Tousethecalculatorclick here.
TechnicalNotes
- Doxorubicinisafluorescentmoleculewithλex470nmandλem585nm.Ifyouareusingafluorescenttagonyourantibodyorligand,youneedtomakesurethattheywillnotinterferewitheachother.
- EDCandsulfo-NHSshouldbepreparedimmediatelybeforeuseandkeptatroomtemperature.
- TheactivationreactionwithEDCandSulfo-NHSismostefficientatpH4.5-7.2,andEDCreactionsareoftenperformedinatpH4.7-6.0.Forthisreason,wehaveformulatedtheliposomesinPBSbufferandadjustedthepHto6.
- ReactionofSulfo-NHS-activatedmoleculeswithprimaryaminesismostefficientatpH7-8,andSulfo-NHS-esterreactionsareusuallyperformedinphosphate-bufferedsaline(PBS)atpH7.2-7.5.
- Trisbuffershouldneverbeusedinanystepoftheprocesssinceitcontainsamine.
- IfyouareusingaligandorpeptidethatishydrophobicthenitisrecommendedtosolubilizeitinDMSOorDMFandthenaddthebuffertoit.Itisrecommendednottousemorethan5%volumeofDMSOorDMFinthesolution.DMFandDMSOarebothcompatIBLewithliposomesandtheyarealsomiscibleinwater.Otherorganicsolventsuchasethanolandchloroformarenotcompatiblewithliposomesandwillcausetheliposomestolyse.IfyouendupusingDMSOorDMFthenaftertheconjugationreactionisdone,youneedtoremoveDMSOandDMFfromtheliposomes.InordertodothatyouneedtouseadialysiscassettethatismadefromREGENERATEDCELLULOSEMEMBRANE.NOTE:NotallmembranesarecompatiblewithDMFandDMSO.WerecommendusingaSlide-A-Lyzer™MINIDialysisDevicewithMWCOof2KmadefromregeneratedcellulosemembranemanufacturedbyThermofisher.AfterDMSOorDMFisremoved,youcanuseFloat-A-Lyzer®dialysisdeviceforthefinalstepofcleaninguptheprep.
- Liposomesshouldbekeptat4°CandNEVERbefrozen.
Database
Directlinktothedatabasepageforeasynavigation:ImmunoliposomesConjugationDatabase
Appearance
Immunodox®-CarboxylicAcidisaredtranslucentliquidmadeofnanosizeunilamellarliposomes.Usuallyduetothesmallsizeofliposomesnosettlingwilloccurinthebottomofthevial.Theliposomesarepackagedinanambervial.
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®-CarboxylicAcidismadeondailybasis.Thebatchthatisshippedismanufacturedonthesameday.Itisadvisedtousetheproductswithin4monthsofthemanufacturingdate.
ReferencesandbackgroundreADIng
1.HermansonGT.Bioconjugatetechniques.Academicpress;2013Jul25.
2.TorchilinV,WeissigV,editors.Liposomes:apracticalapproach.OxfordUniversityPress;2003Jun5.
3.GrabarekZ,GergelyJ.Zero-lengthcrosslinkingprocedurewiththeuseofactiveesters.Analyticalbiochemistry.1990Feb15;185(1):131-5.
4.YanL,CraytonSH,ThawaniJP,AmirshaghaghiA,TsourkasA,ChengZ.ApH‐ResponsiveDrug‐DeliveryPlatformBasedonGlycolChitosan–CoatedLiposomes.Small.2015Oct1;11(37):4870-4.
5. Silva-LópezEI,EdensLE,BardenAO,KellerDJ,BrozikJA.ConditionsforliposomeadsorptionandbilayerformationonBSApassivatedsolidsupports.Chemistryandphysicsoflipids.2014Oct31;183:91-9.
6.HazraM,SinghSK,andRayS.SurfaceModificationofLiposomalVaccinesbyPeptideConjugation.JournalofPharmaSciTech,2011;1(1):41-47.
ebiomall.com






>
>
>
>
>
>
>
>
>
>
>
>
转录的只是插入的片断,怎么会跟模板一样大呢,一般情况下应该比模板小多了。我都是跑电泳,严格来说应该跑变性的;嫌麻烦可以非变性,快速(防止RNA降解)十分钟即可;抛出来的带会有两条,上面大的是模板,下面一条比较亮的是RNA,那么你的转录就 成功了。
PCR第一个步骤如果没记错的话应该叫“变性”, PCR的话是不需要解旋酶的,直接利用DNA的高温变性特性,在高温下,使氢键断开,DNA双链恢复为单链。 (还有解旋酶好像是解除双螺旋的结构,是一种拓扑异构酶,对于氢键的打开没有贡献吧
对于新手来说购买反转录试剂盒是比较理想的,买一个kit看看说明书操作就可以了。推荐两款kit TAKARA和HaiGene,这两款试剂盒都能对RNA样品中的gDNA有效去除,因此对RNA质量的要求不高。TAKARA的RR047A操作方便,反转录温度为37℃,对于大多数试验来讲是满足要求的。HaiGene的D0401操作要多一个步骤,但其反转录温度是55℃(耐高温的反转录酶),提高了反转录温度使得高GC含量、复杂模板、长mRNA的模板都能有效反转录,因此其反转录效率更高,更能够获得样本中基因的真实表达量。如果后续试验是RealTime PCR、ORF克隆、高GC含量、或者你的待研究基因结构复杂程度未知,还是选用耐高温的反转录酶更理想。对于反转录高手来说,直接购买反转录酶、再购买Rnase Inhibitor自己配制反转录体系就可以了。对于样本量大的课题组来讲,相对还是比较经济的。选择反转录酶时仅需要考虑是否需要耐高温的酶,来克服目的基因的复杂结构就可以了。PROMEGA、TAKARA、HaiGene、 TRANSGEN等品牌的反转录酶性价比还都是不错的。Life、NEB的也不错,不过性价比一般,不一一解释了。
首先,不否认它比大多数国产的试剂盒做得好,提取的纯度、方便度和量,都还很不错。
其次,它是日本的。so我觉得实验室用用天根的,就非常好了。拒绝日货,从实验室做起。