
Duringthepastfivedecades,varioustypesofchemistrieshavebeenusedforconjugationofmoleculessuchasantibodiestothesurfaceoftheliposomes.Ingeneral,theconjugationcanbeachievedthroughtheN-terminus,theC-terminusortheavailablesulfur(e.g.Fab’fractionorthiolatedAb).NotallchemistrieshavethesameyieldandefficiencyofconjugationandoftenreproducingbiocompatIBLebatchescanbeachallenge.Theliposomescontainingpyridyldithiopropionate(PDP)lipidsareusedtoconjugateproteins,antibodiesandothermoleculescontainingthereactivemoiety.PDPlipidsarenotaswidelyusedasmaleimidelipids,buttheydohavetheirownnicheapplication.ThePDPgroupcontainsdisulfide,whichcanreactwithsulfhydrylorthiolatedproteins/antibodies.Therefore,PDP-functionalizedliposomescanbeusedintwoways:
MethodA.Inthisapproach,thepyridyldithiogrouponthedistalendsofthePEGchainscontainsPDPisforestreducedbyareducingagent(dithiothreitol,DTT).Maleimide-containingantibodiesarethenefficientlycoupledtothesurfaceofliposomes.Thethiol-maleimideprocedureisoneofthemostdesirablereactionsinbioconjugatechemistryduetoitssimplicityandhighcouplingefficiencyinaqueoussolution.Thereaction,whichisbasedonthestablethioetherlinkagebetweenathiolgroup(reducedformofPDP-liposome)andthecorrespondingmaleimidegroup,occursselectivelyandirreversiblyatneutralpH(6.5-7.5),andtheformedbondsarenotcleavedbyreducingagents.Inaddition,duetothepresenceoftwodifferentoxidationstatesofsulfurresidues(oxidizedandreducedstatesasadisulfidebondandsulfhydrylgroup,respectively)onthetwoconjugatingcomponents(i.e.,theliposomeandprotein/antibody),theprobABIlityofthecrosslinkingofthehomologousagentsislow.Therefore,protein-proteinandliposome-liposomecrosslinkingdoesnotusuallyhappen.
MethodB.Alternatively,thePDPgroupcanparticipateindisulfideexchangereactionswiththiolspresentontargetingproteins/antibodies.Thecouplingreactionisfastandconductedundermildconditions.However,theformeddisulfidebondshavebeenreportedtobelessstablethanthioetherbonds.Moreover,eveninanalkalinemedium(pH8.0),thiolgroupsareoxidized.Thedisulfidebondformedbetweentheprotein/antibodyandliposomescanalsobebrokeninthepresenceofareducingagentandtherefore,theconjugationreactionisreversible.
MethodA. Conjugationofmaleimide-modifiedantibodytoaPDP-modifiedliposome.
MethodB.Conjugationofathiol-modifiedantibodytoaPDP-modifiedliposome.
ImmunoFluor™-PDPisaPEGylatedproduct.Forotherreactive(PEGylatedandnon-PEGyalatedproducts)ImmunosFluor™productssuitableforothertypesofconjugationmethodsee here.
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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。
定性ELISA只能粗略表示样本待测物含量在某个特定值以上或以下,定性ELISA通常设置阳性对照(P)、和阴性对照(N),结果分别用“阴性”和“阳性”表示。ELISA定性测定的“阴性”和“阳性”的判断标准是试剂盒所确定的阳性判断值,即cut-off值。
定量ELISA是通过一系列不同已知浓度的标准品所对应的OD值做出标准曲线,然后将样本的OD值代入标准曲线,计算出样本中待测物的含量。百特纯大分子Meretciel的定量ELISA试剂盒还可以。
谢谢谢
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。
MicroBCA试剂测定范围是0.5-20μg/ml
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