Department of Chemistry, York University, 4700 Keele St., Toronto, ON M3J 1P3, Canada.
Department of Physics and Astronomy, York University, 4700 Keele St., Toronto, ON M3J 1P3, Canada.
Biosensors (Basel). 2022 Oct 2;12(10):817. doi: 10.3390/bios12100817.
A portable and sensitive time-resolved biosensor for capturing very low intensity light emission is a promising avenue to study plant delayed fluorescence. These weak emissions provide insight on plant health and can be useful in plant science as well as in the development of accurate feedback indicators for plant growth and yield in applications of agricultural crop cultivation. A field-based delayed fluorescence device is also desirable to enable monitoring of plant stress response to climate change. Among basic techniques for the detection of rapidly fluctuating low intensity light is photon counting. Despite its vast utility, photon counting techniques often relying on photomultiplier tube (PMT) technology, having restricted use in agricultural and environment measurements of plant stress outside of the laboratory setting, mainly due to the prohibitive cost of the equipment, high voltage nature, and the complexity of its operation. However, recent development of the new generation solid-state silicon photomultiplier (SiPM) single photon avalanche diode array has enabled the availability of high quantum efficiency, easy-to-operate, compact, photon counting systems which are not constrained to sophisticated laboratories, and are accessible owing to their low-cost. In this contribution, we have conceived, fabricated and validated a novel SiPM-based photon counting device with integrated plug-and-play excitation LED, all housed inside a miniaturized sample chamber to record weak delayed fluorescence lifetime response from plant leaves subjected to varying temperature condition and drought stress. Findings from our device show that delayed fluorescence reports on the inactivation to the plant's photosystem II function in response to unfavorable acute environmental heat and cold shock stress as well as chronic water deprivation. Results from our proof-of-concept miniaturized prototype demonstrate a new, simple and effective photon counting instrument is achieved, one which can be deployed in-field to rapidly and minimally invasively assess plant physiological growth and health based on rapid, ultra-weak delayed fluorescence measurements directly from a plant leaf.
一种用于捕获极弱光发射的便携式、高灵敏度的时间分辨生物传感器，是研究植物延迟荧光的有前途的途径。这些微弱的发射提供了对植物健康的深入了解，并且在植物科学中以及在农业作物种植应用中开发用于植物生长和产量的准确反馈指标方面都很有用。基于现场的延迟荧光设备也很理想，可以实现对植物对气候变化的应激反应的监测。在用于检测快速波动的低强度光的基本技术中，有一种是光子计数。尽管光子计数技术具有广泛的用途，但由于设备成本高昂、高压特性以及操作复杂性，它通常依赖于光电倍增管（PMT）技术，在实验室以外的农业和环境测量植物应激方面的应用受到限制。然而，新一代固态硅光电倍增管（SiPM）单光子雪崩二极管阵列的最新发展使得高量子效率、易于操作、紧凑、不受复杂实验室限制的光子计数系统成为可能，并且由于其低成本而变得可行。在本研究中，我们设计、制造并验证了一种新型基于 SiPM 的光子计数设备，该设备具有集成的即插即用激发 LED，全部安装在一个小型化的样品室内，用于记录来自不同温度条件和干旱胁迫下的植物叶片的微弱延迟荧光寿命响应。我们的设备的研究结果表明，延迟荧光报告了植物的光系统 II 功能在不利的急性环境热和冷冲击应激以及慢性水分剥夺下的失活情况。我们的小型化原型设备的结果表明，已经实现了一种新的、简单有效的光子计数仪器，它可以部署在现场，根据直接从植物叶片进行的快速、超弱延迟荧光测量，快速、微创地评估植物的生理生长和健康状况。
