藉由光保護基調變優化具光可控性的紫杉醇螢光探針

Abstract

我們開發了一種具備雙重功能、可透過光啟動的微管探針，其設計基於已知具有穩定微管作用的藥物 paclitaxel (PTX)。此探針結合了兩種光保護基（photocage）：DEACM 與一系列 o-nitrobenzyl（oNB）衍生物，能同時光控其生物活性與螢光訊號。 我們合成並系統性評估了六種 oNB 衍生 quencher 的光物理與光化學特性。實驗結果顯示，2,4-dinitrobenzyl (2,4-DNB) 具有最強的螢光抑制能力，而 2,6-dinitrobenzyl (2,6-DNB) 則展現最快的光解速率。 生物實驗證實，double-caged PTX 探針在照光前毒性明顯降低，照光後則可回復其對微管的作用力。雖然在螢光顯微鏡下觀察仍受限於光漂白與訊號微弱的問題，預期未來透過導入如 AzCM 等更穩定的螢光分子，能有效提升探針表現。 本研究提出一項可光控的雙重保護基策略，成功應用於微管探針的建構上，為細胞內微管相關機制的研究提供了有力的化學生物學工具。

We have developed a dual-functional, light-activated microtubule probe based on paclitaxel (PTX), a well-characterized microtubule-stabilizing agent. Our probe integrates two photocages—DEACM and a series of o-nitrobenzyl (oNB) derivatives—allowing simultaneous optical control over both biological activity and fluorescence signal. A library of six oNB-derived quenchers was synthesized and evaluated for their photophysical and photochemical performance. Among them, 2,4-dinitrobenzyl (2,4-DNB) demonstrated the most efficient fluorescence quenching, while 2,6-dinitrobenzyl (2,6-DNB) exhibited the fastest photolysis rate. Biological assays confirmed that the double-caged PTX probes displayed reduced cytotoxicity prior to light activation and restored microtubule activity post-irradiation. Although fluorescence imaging using microscopy encountered issues such as photobleaching and limited signal, future optimization—including the use of more photostable fluorophores like AzCM—is anticipated to enhance performance. In summary, we present a dual-caging strategy for constructing light-controllable microtubule probes. This platform provides a valuable chemical biology tool for dissecting microtubule-mediated processes in live cells.