葉酸載體(Reduced folate carrier, RFC)，是哺乳類動物細胞中抗葉酸藥物，如甲氨蝶呤（Methotrexate, MTX）的主要運送通道的轉運蛋白。另一方面，葉酸受體（Folate receptors, FRs）可將葉酸與抗葉酸藥物，透過內吞做用將其胞吞進細胞中。在癌細胞膜表面上，常過度表現葉酸受體，迄今納米藥物載體設計上，通常是經由葉酸受體介導的內吞作用，然後讓藥物載體在細胞內釋放MTX。 那麼使用納米載體運送MTX時，應該在細胞外或細胞內釋放，才能提供殺死癌細胞的最佳功效? 為了解決這個問題，本實驗設計了使用近紅外光刺激調控釋放MTX奈米材料，以證明在HeLa細胞中，MTX的細胞外(透過RFC路徑)和細胞內(透過FRs路徑)釋放，哪一種路徑對於奈米藥物載體釋放MTX有較佳的效率，而結果顯示透過細胞內運送對HeLa細胞有更好的功效。

Reduced folate carrier (RFC) is a transporting protein as the major delivery channel for the antifolates, like methotrexate (MTX), in mammalian cells. On the other hand, folate receptors (FRs) is eligible to activate endocytotic pathway to folate and antifolates. Folate receptor overexpressed on several cancer cells have often been an access for MTX carried made by Nanocarriers via receptor-mediated endocytosis. A question is raised to be answered if MTX should be called extracellularly Or intracellularly to achieve optimal efficacy in killing cancer cells when using nanocarriers. To solve this question, A photo-triggering nano-motif based on near-infrared light has been designed to demonstrate extracellular and intracellular Release of MTX in HeLa cells. The results display intracellular delivery leading to better efficacy against HeLa Cells compared to extracellular approach.

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