Molecular rotors - fluorescent biosensors for viscosity and flow
Molecular rotors - fluorescent biosensors for viscosity and flow
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DOI：
10.1039/b618415d
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发表时间：
2007-01-01
影响因子：
3.2
通讯作者：
Theodorakis, Emmanuel A.
中科院分区：
文献类型：
--
作者：
Haidekker, Mark A.;Theodorakis, Emmanuel A.
粘度是流体抵抗流动梯度（剪切速率）的阻力的量度。流动和粘度在所有生物系统中起着重要的作用，从微观（例如，例如，在一个实施例中，细胞）到系统水平。许多测量粘度和流量的方法都有缺点，例如测量过程繁琐且耗时，仪器昂贵，或者对批量样品大小的限制。已知荧光环境敏感染料显示高灵敏度和高空间和时间分辨率。分子转子是一组荧光分子，其在光激发时形成扭曲的分子内电荷转移（TICT）状态，因此表现出两种竞争的去激发途径：荧光发射和来自TICT状态的非辐射去激发。由于TICT的形成依赖于粘度，因此分子转子的发射强度取决于溶剂的粘度。此外，最近描述了发射强度的剪切应力依赖性。虽然分子转子的物理过程被广泛探索，但作为粘度和流体流动传感器的分子转子的实际应用引入了额外的挑战。基于强度的测量受流体光学性质和染料浓度的影响，并且溶剂-染料相互作用需要将测量系统校准到特定溶剂。比例染料和测量系统有助于解决这些挑战。此外，分子转子与特定识别基团的组合允许它们靶向特定位点，例如细胞膜或细胞质。因此，分子转子出现作为新的生物传感器的体积和局部微粘度，并在微观尺度上的流动和流体剪切应力，并与实时响应。
Viscosity is a measure of the resistance of a fluid against gradients in flow ( shear rate). Both flow and viscosity play an important role in all biological systems from the microscopic ( e. g., cellular) to the systemic level. Many methods to measure viscosity and flow have drawbacks, such as the tedious and time-consuming measurement process, expensive instrumentation, or the restriction to bulk sample sizes. Fluorescent environment-sensitive dyes are known to show high sensitivity and high spatial and temporal resolution. Molecular rotors are a group of fluorescent molecules that form twisted intramolecular charge transfer ( TICT) states upon photoexcitation and therefore exhibit two competing deexcitation pathways: fluorescence emission and non-radiative deexcitation from the TICT state. Since TICT formation is viscosity-dependent, the emission intensity of molecular rotors depends on the solvent's viscosity. Furthermore, shear-stress dependency of the emission intensity was recently described. Although the photophysical processes are widely explored, the practical application of molecular rotors as sensors for viscosity and the fluid flow introduce additional challenges. Intensity-based measurements are influenced by fluid optical properties and dye concentration, and solvent-dye interaction requires calibration of the measurement system to a specific solvent. Ratiometric dyes and measurement systems help solve these challenges. In addition, the combination of molecular rotors with specific recognition groups allows them to target specific sites, for example the cell membrane or cytoplasm. Molecular rotors are therefore emerging as new biosensors for both bulk and local microviscosity, and for flow and fluid shear stress on a microscopic scale and with real-time response.