Analyte-Reactive Amphiphilic Thermoresponsive Diblock Copolymer Micelles-Based Multifunctional Ratiometric Fluorescent Chemosensors
Analyte-Reactive Amphiphilic Thermoresponsive Diblock Copolymer Micelles-Based Multifunctional Ratiometric Fluorescent Chemosensors
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基于分析物反应性两亲热响应二嵌段共聚物胶束的多功能比例荧光化学传感器
DOI：
10.1021/ma2001146
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发表时间：
2011-06-28
期刊：
影响因子：
5.5
通讯作者：
Liu, Shiyong
中科院分区：
文献类型：
--
作者：
Hu, Jinming;Dai, Lu;Liu, Shiyong
我们报告了基于两亲性热响应二嵌段共聚物胶束的多功能比率荧光化学传感器的制备，用于金属离子（Hg2+和Cu2+）、pH和温度。荧光共振能量转移（FRET）对由4-（2-丙烯酰氧基乙基氨基）-7-硝基-2,1,3-苯并恶二唑（NBDAE）供体和螺内酰胺形式的罗丹明B基潜在受体（RhBHA）组成，具有pH和Hg2+（Cu2+）反应特性，分别共聚成疏水性PS和热响应PNIPAM嵌段P(St-co-NBDAE)-b-P(NIPAM-co-RhBHA)两亲性二嵌段共聚物，其中PS和PNIPAM代表聚苯乙烯和聚(N-异丙基丙烯酰胺)。在水溶液中，FRET 对标记的二嵌段共聚物自组装成纳米级胶束，其中 NBDAE 部分位于胶束核心中，RhBHA 位于热响应冠中。由于Hg2+离子和酸性pH可以诱导RhBHA从非荧光螺内酰胺形式转变为高荧光无环形式，并且分别位于胶束核和冠内的NBDAE和RhBHA部分之间的FRET过程可以有效地开启。因此，这些纳米级胶束可以作为 Hg2+ 离子和 pH 的优异比率荧光探针，伴随着从绿色到橙色的荧光转变以及从几乎无色到粉红色的比色变化。在胶束浓度为 0.05 g/L 和 25°C 时，Hg2+ 离子的检测限可降至约 14.8 ppb。另一方面，Cu2+离子可以定量诱导RhBHA部分开环并提供非荧光残基，可以有效猝灭NBDAE发射。根据 NBDAE 发射强度的相对变化，Cu2+ 检测限可降至约 4.3 ppb。最重要的是，FRET 对的空间距离可以通过热诱导的 PNIPAM 胶束冠塌陷来轻松调节，从而显着提高 FRET 效率并提高 pH 检测灵敏度。这项工作代表了基于两亲性嵌段共聚物胶束的多功能比例荧光探针的概念验证示例，适用于两种类型的金属离子（Hg2+和Cu2+）、pH和温度，这预示着它们作为具有成像、传感和治疗药物控释等集成功能的纳米载体的潜在应用。
We report on the fabrication of amphiphilic thermoresponsive diblock copolymer micelle-based multifunctional ratiometric fluorescent chemosensors for metal ions (Hg2+ and Cu2+), pH, and temperatures. A fluorescence resonance energy transfer (FRET) pair consisting of 4-(2-acryloyloxyethylarnino)-7-nitro-2,1,3-benzoxadiazole (NBDAE) donor and rhodamine B-based potential acceptor (RhBHA) in the spirolactam form with pH and Hg2+ (Cu2+)-reactive characteristics were respectively copolymerized into the hydrophobic PS and thermoresponsive PNIPAM block of P(St-co-NBDAE)-b-P(NIPAM-co-RhBHA) amphiphilic diblock copolymers, where PS and PNIPAM represent polystyrene and poly(N-isopropylacrylamide). In aqueous solution, the FRET pair-labeled diblock copolymer self-assembles into nanosized micelles with NBDAE moieties located in the micellar cores and RhBHA in the thermoresponsive coronas. Because of that Hg2+ ions and acidic pH can induce the transformation of RhBHA from the nonfluorescent spirolactam form to highly fluorescent acyclic form, and the FRET process between NBDAE and RhBHA moieties, located respectively within micellar cores and coronas, can be effectively switched on. Thus, these nanosized micelles can serve as excellent ratiometric fluorescent probes for Hg2+ ions and pH, accompanied by fluorometric transition from green to orange and colorimetric change from almost colorless to pink. At a micellar concentration of 0.05 g/L and 25 degrees C, the detection limit of Hg2+ ions can be down to similar to 14.8 ppb. On the other hand, Cu2+ ions can quantitatively induce the ring-opening of RhBHA moieties and afford nonfluorescent residues, which can effectively quench the NBDAE emission. On the basis of the relative changes in NBDAE emission intensities, the Cu2+ detection limit can be down to similar to 4.3 ppb. Most importantly, the spatial distance of the FRET pair can be facilely tuned via thermo-induced collapse of PNIPAM micellar coronas, which dramatically increase the FRET efficiency and enhance the pH detection sensitivity. This work represents a proof-of-concept example of amphiphilic block copolymer micelles-based multifunctional ratiometric fluorescent probes for two types of metal ions (Hg2+ and Cu2+), pH, and temperatures, which augurs well for their potential applications as nanocarriers with integrated functions such as imaging, sensing, and controlled-release of therapeutics.