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.
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向左转|向右转
如果是用转录出的cDNA做那跟平时就一样了。不需要特别的试剂盒、
1.模板提取(一般为RNA):Trizol、氯仿、异丙醇、无水乙醇、DEPC处理水
2.模板浓度测定:分光光度计或NanoDrop
3.逆转录:逆转录试剂盒(或者一步法试剂盒),这一步可以用普通PCR做,也可以用水域做。
4.荧光定量PCR试剂:通常有用SYBR Green Mix做的,但是这里建议你用EvaGreen做,灵敏度和平行性都要好于SYBR Green,并且如果你那是ABI或者Stratagene的PCR如果用SYBR Green还需要加一步Rox很麻烦。
5.其他:除了以上的那些还需要离心管、PCR管或板(Axygen反应比较好)、移液枪等,暂时就想到这么多。
和RevertAid™HMinusFirstStrandcDNASynthesisKit,FirstStrandcDNASynthesisKit
大家又没有用过,这个公司的酶据说很好啊。
逆转录(reverse transcription)是以RNA为模板合成DNA的过程,即RNA指导下的DNA合成。此过程中,核酸合成与转录(DNA到RNA)过程与遗传信息的流动方向(RNA到DNA)相反,故称为逆转录。逆转录过程是RNA病毒的复制形式之一,需逆转录酶的催化。 逆转录过程的揭示是分子生物学研究中的重大发现,是对中心法则的重要修正和补充。人们通过体外模拟该过程,以样本中提取的mRNA为模板,在逆转录酶的作用下,合成出互补的cDNA,构建cDNA文库,并从中筛选特异的目的基因。该方法已成为基因工程技术中最常用的获得目的基因的策略之一。
加尾法是采用加A酶先对mirna进行加尾,然后再用带oligodt的引物反转录,他的反转录引物是通用的,一次反转录可以获得所有miRNA的cdna,效率高。茎环法是采用特异性反转录引物序列+颈环结构作为反转录引物进行反转录的,一次反转录只能获得一种mirna的cdna,可能有几种一起反转录的,这个我不太清楚一起反转录的效果。然后茎环法的经典即ABI的探针法定量试剂盒。我用过茎环法反转录+染料法定量的,下游引物为通用引物,结果不太好,就现在用的这家的他采用的是双向引物都是特异性的,效果还可以。不知道我说的清楚不,希望能对你有帮助。


