Biotinylated liposomes can be conjugated non-covalently with (strept)avidin through either direct interaction with the protein/antibody conjugated to (strept)avidin or by coupling with other biotinylated proteins using (strept)avidin as a bridging molecule. Both avidin and (strept)avidin form strong non-covalent bond with biotin. The high resistance to breakdown makes them very useful in bioconjugate chemistry. However, (strept)avidin has replaced avidin in most bioconjugation applications due to its enhanced properties. NeutrAvidin (ThermoFisher) is a modified avidin without negative properties. It performs much better than original avidin and sometimes (strept)avidin.
In order to exploit the high-affinity interaction of biotin with (strept)avidin, a two-step “sandwich” protocol (Method A) has been developed for the preparation of targeted immunoliposomes. In this methodology, (strept)avidin is first attached to biotinylated liposomes, then a biotin-modified protein/antibody is introduced into the biotinylated (strept)avidin-labeled liposomes. This noncovalent approach is rapid, extremely versatile and applicable to numerous targeting ligands of interest with respect to in vitro and in vivo applications. Alternatively, instead of forming a (strept)avidin bridge, (strept)avidin molecule can also be covalently conjugated to antibody or ligand (Method B) and non-covalently bound to liposomes containing biotin on surface in order to form immunoliposomes.
ImmunoFluor™-Biotin is a PEGylated product. For other amine reactive (PEGylated and non-PEGyalated products) and also ImmunoFluor™ products suitable for other types conjugation methods see here.
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采用抗-HBe抗体包被反应板，加入校准品及被测样本，同时加入定量HBeAg中和抗原，经过振荡孵育,洗板后再加入铕标记的抗-HBe，若标本中抗-HBe浓度高，HBeAg将被大量中和，使最后形成的抗-HBe-HBeAg-铕标记抗-HBe复合物减少。增强液（β－NTA）将标记在抗体上的Eu3+解离到溶液中，Eu3+和增强液中的有效成分形成高荧光强度的螯合物，荧光强度和样本中的抗-HBe浓度成反比。
