Department of Physics, Cavendish Laboratory , University of Cambridge , J. J. Thomson Avenue , Cambridge CB3 0HE , United Kingdom.
Department of Physiology, Development, and Neuroscience , University of Cambridge , Downing Street , Cambridge CB2 3DY , United Kingdom.
Nano Lett. 2019 Dec 11;19(12):8539-8549. doi: 10.1021/acs.nanolett.9b03026. Epub 2019 Nov 7.
Luminescent semiconductor quantum dots (QDs) have recently been suggested as novel probes for imaging and sensing cell membrane voltages. However, a key bottleneck for their development is a lack of techniques to assess QD responses to voltages generated in the aqueous electrolytic environments typical of biological systems. Even more generally, there have been relatively few efforts to assess the response of QDs to voltage changes in live cells. Here, we develop a platform for monitoring the photoluminescence (PL) response of QDs under AC and DC voltage changes within aqueous ionic environments. We evaluate both traditional CdSe/CdS and more biologically compatible InP/ZnS QDs at a range of ion concentrations to establish their PL/voltage characteristics on chip. Wide-field, few-particle PL measurements with neuronal cells show the QDs can be used to track local voltage changes with greater sensitivity (ΔPL up to twice as large) than state-of-the-art calcium imaging dyes, making them particularly appealing for tracking subthreshold events. Additional physiological observation studies showed that while CdSe/CdS dots have greater PL responses on membrane depolarization, their lower cytotoxicity makes InP/ZnS far more suitable for voltage sensing in living systems. Our results provide a methodology for the rational development of QD voltage sensors and highlight their potential for imaging changes in cell membrane voltage.
荧光半导体量子点（QDs）最近被提议作为新型探针用于细胞膜电压的成像和传感。然而，其发展的一个关键瓶颈是缺乏技术来评估 QD 对生物系统中典型的水相电解质环境中产生的电压的响应。更普遍的是，很少有努力评估 QD 对活细胞中电压变化的响应。在这里，我们开发了一个在水相离子环境中的交流和直流电压变化下监测 QD 光致发光（PL）响应的平台。我们在一系列离子浓度下评估了传统的 CdSe/CdS 和更具生物相容性的 InP/ZnS QD，以在芯片上建立它们的 PL/电压特性。具有神经元细胞的宽场、少粒子 PL 测量表明，与最先进的钙成像染料相比，这些 QD 可以更灵敏地（ΔPL 高达两倍）跟踪局部电压变化，这使得它们特别适合跟踪亚阈值事件。其他生理观察研究表明，虽然 CdSe/CdS 点在膜去极化时有更大的 PL 响应，但它们的低细胞毒性使得 InP/ZnS 更适合用于活体系统中的电压传感。我们的结果为 QD 电压传感器的合理开发提供了一种方法，并强调了它们在细胞膜电压成像变化方面的潜力。
