Optical biosensors have been invaluable tools in neuroscience research, as they provide the ability to directly visualize neural activity in real time, with high specificity, and with exceptional spatial and temporal resolution. Notably, a majority of these sensors are based on fluorescent protein scaffolds, which offer the ability to target specific cell types or even subcellular compartments. However, fluorescent proteins are intrinsically bulky tags, often insensitive to the environment, and always require excitation light illumination. To address these limitations, there has been a proliferation of alternative sensor scaffolds developed in recent years, including hybrid sensors that combine the advantages of synthetic fluorophores and genetically encoded protein tags, as well as bioluminescent probes. While still in their early stage of development as compared with fluorescent protein-based sensors, these novel probes have offered complementary solutions to interrogate various aspects of neuronal communication, including transmitter release, changes in membrane potential, and the production of second messengers. In this Review, we discuss these important new developments with a particular focus on design strategies.

中文翻译：

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荧光蛋白之外：用于神经活动成像的杂交和生物发光指示剂

光学生物传感器已经成为神经科学研究中不可估量的工具，因为它们提供了实时，高特异性，超凡的时空分辨率直接可视化神经活动的能力。值得注意的是，这些传感器中的大多数都基于荧光蛋白支架，该支架提供了靶向特定细胞类型甚至亚细胞区室的能力。但是，荧光蛋白本质上是笨重的标签，通常对环境不敏感，并且始终需要激发光照射。为了解决这些局限性，近年来开发出了替代传感器支架，其中包括结合了合成荧光团和遗传编码蛋白标签以及生物发光探针优点的混合传感器。与基于荧光蛋白的传感器相比，这些新颖的探针虽然仍处于开发的早期阶段，但它们提供了互补的解决方案来询问神经元通讯的各个方面，包括变送器释放，膜电位的变化以及第二信使的产生。在这篇评论中，我们讨论了这些重要的新发展，特别侧重于设计策略。