Release of hydrophobic molecules from polymer micelles into cell membranes revealed by Forster resonance energy transfer imaging
Release of hydrophobic molecules from polymer micelles into cell membranes revealed by Forster resonance energy transfer imaging
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DOI：
10.1073/pnas.0707046105
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发表时间：
2008-05-06
影响因子：
11.1
通讯作者：
Cheng, Ji-Xin
中科院分区：
文献类型：
--
作者：
Chen, Hongtao;Kim, Sungwon;Cheng, Ji-Xin
一般认为，聚合物胶束在给药进入血液后，携带药物分子，直到它们被吸收到细胞中，然后在细胞内释放。当前的工作重新审视了这一传统智慧。采用双标记胶束，其中含有荧光标记的共聚物和包埋在聚合物胶束核心的疏水荧光探针的研究表明，细胞对疏水探针的摄取要比标记的共聚物快得多。这一结果表明，核心中的疏水探针是从细胞外空间的胶束中释放出来的。福斯特共振能量转移（FRET）成像和光谱学用于实时监测这一过程。FRET对DiIC（18(3)）和DiOC（18(3)）被加载到单甲氧基聚乙二醇-块聚（D， l -乳酸）胶束中。通过监测FRET效率，证明了核负载探针释放到模型膜。在给肿瘤细胞注入聚合物胶束的过程中，细胞膜和细胞内部的FRET都有所减少，这表明载核探针在内化之前释放到细胞膜上。在紫杉醇负载胶束的过程中，质膜上FRET的减少也被观察到。综上所述，我们的研究结果提示了一种膜介导的途径，用于细胞摄取预载在聚合物胶束中的疏水分子。质膜为胶束释放的疏水分子提供了一个暂时的住所，然后将其传递到细胞内的目标目的地。讨论了聚乙二醇壳在分子从胶束到膜的运输中的假定作用。
it is generally assumed that polymeric micelles, upon administration into the blood stream, carry drug molecules until they are taken up into cells followed by intracellular release. The current work revisits this conventional wisdom. The study using dual-labeled micelles containing fluorescently labeled copolymers and hydrophobic fluorescent probes entrapped in the polymeric micelle core showed that cellular uptake of hydrophobic probes was much faster than that of labeled copolymers. This result implies that the hydrophobic probes in the core are released from micelles in the extracellular space. Forster resonance energy transfer (FRET) imaging and spectroscopy were used to monitor this process in real time. A FRET pair, DiIC(18(3)) and DiOC(18(3)), was loaded into monomethoxy poly(ethylene glycol)-block-poly(D,L-lactic acid) micelles. By monitoring the FRET efficiency, release of the core-loaded probes to model membranes was demonstrated. During administration of polymeric micelles to tumor cells, a decrease of FRET was observed both on the cell membrane and inside of cells, indicating the release of core-loaded probes to the cell membrane before internalization. The decrease of FRET on the plasma membrane was also observed during administration of paclitaxel-loaded micelles. Taken together, our results suggest a membrane-mediated pathway for cellular uptake of hydrophobic molecules preloaded in polymeric micelles. The plasma membrane provides a temporal residence for micelle-released hydrophobic molecules before their delivery to target intracellular destinations. A putative role of the PEG shell in the molecular transport from micelle to membrane is discussed.