Department of Bioengineering, University of Pennsylvania, 210 South 33rd Street, 240 Skirkanich Hall, Philadelphia, PA 19104, USA.
Proc Natl Acad Sci U S A. 2011 Aug 23;108(34):13984-9. doi: 10.1073/pnas.1102125108. Epub 2011 Aug 15.
Probes embedded within a structure can enable prediction of material behavior or failure. Carefully assembled composites that respond intelligently to physical changes within a material could be useful as intrinsic sensors. Molecular rotors are one such tool that can respond optically to physical environmental changes. Here, we propose to use molecular rotors within a polymersome membrane to report membrane stress. Using supermolecular porphyrin-based fluorophores as rotors, we characterize changes in the optical emission of these near-infrared (NIR) emissive probes embedded within the hydrophobic core of the polymersome membrane. The configuration of entrapped fluorophore depends on the available space within the membrane; in response to increased volume, emission is blue shifted. We used this feature to study how shifts in fluorescence correlate to membrane integrity, imparted by membrane stress. We monitored changes in emission of these porphyrin-based fluorophores resulting from membrane stress produced through a range of physical and chemical perturbations, including surfactant-induced lysis, hydrolytic lysis, thermal degradation, and applied stress by micropipette aspiration. This paper comprehensively illustrates the potential for supermolecular porphyrin-based fluorophores to detect intrinsic physical changes in a wide variety of environments, and suggests how molecular rotors may be used in soft materials science and biology as sensors.
嵌入结构内的探针可用于预测材料的行为或失效。精心组装的复合材料可以对材料内部的物理变化做出智能响应，可用作固有传感器。分子转子就是这样一种可以对物理环境变化做出光学响应的工具。在这里，我们提议在聚合物囊泡膜内使用分子转子来报告膜应力。我们使用超分子卟啉基荧光团作为转子，来表征这些近红外（NIR）发射探针在聚合物囊泡膜疏水性核心内的光学发射变化。被包埋的荧光团的构型取决于膜内的可用空间；响应于体积增加，发射发生蓝移。我们利用这一特性研究了荧光的位移如何与膜完整性相关联，这是由膜应力引起的。我们监测了这些基于卟啉的荧光团在通过一系列物理和化学扰动产生的膜应力下的发射变化，包括表面活性剂诱导的裂解、水解裂解、热降解以及通过微量移液管抽吸施加的应力。本文全面说明了超分子卟啉基荧光团在各种环境中检测固有物理变化的潜力，并提出了分子转子如何在软物质科学和生物学中作为传感器使用。
