University of Cincinnati, Department of Chemistry, 312 College Dr., 404 Crosley Tower, Cincinnati, OH 45221-0172, USA.
Analyst. 2018 Dec 17;144(1):249-257. doi: 10.1039/c8an01547c.
Guanosine is an important neuromodulator and neuroprotector in the brain and is involved in many pathological conditions, including ischemia and neuroinflammation. Traditional methods to detect guanosine in the brain, like HPLC, offer low limits of detection and are robust; however, subsecond detection is not possible. Here, we present a method for detecting rapid fluctuations of guanosine concentration in real-time using fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes. The optimized waveform scanned from -0.4 V to 1.3 V and back at a rate of 400 V s-1 and application frequency of 10 Hz. Potential limits were chosen to increase selectivity of guanosine over the structurally similar interferent adenosine. Two oxidation peaks were detected with the optimized waveform: the primary oxidation reaction occurred at 1.3 V and the secondary oxidation at 0.8 V. Guanosine detection was stable over time with a limit of detection of 30 ± 10 nM, which permits its use to monitor low nanomolar fluctuations in the brain. To demonstrate the feasibility of the method for in-tissue detection, guanosine was exogenously applied and detected within live rat brain slices. This paper demonstrates the first characterization of guanosine using FSCV, and will be a valuable method for measuring signaling dynamics during guanosine neuromodulation and protection.
鸟苷是大脑中一种重要的神经调质和神经保护剂，参与许多病理状况，包括缺血和神经炎症。传统的检测大脑中鸟苷的方法，如 HPLC，具有较低的检测限和稳健性；然而，无法实现亚秒级的检测。在这里，我们提出了一种使用碳纤维微电极的快速扫描循环伏安法（FSCV）实时检测鸟苷浓度快速波动的方法。优化后的波形以 400 V/s 的速率从-0.4 V 扫描到 1.3 V 再返回，并以 10 Hz 的应用频率进行扫描。选择电位极限以提高鸟苷相对于结构相似的干扰物腺苷的选择性。优化后的波形检测到两个氧化峰：主要氧化反应发生在 1.3 V，次要氧化反应发生在 0.8 V。鸟苷检测随时间稳定，检测限为 30±10 nM，可用于监测大脑中的低纳摩尔波动。为了证明该方法在组织内检测的可行性，将外源性鸟苷应用于并在活的大鼠脑片中进行检测。本文首次用 FSCV 对鸟苷进行了表征，这将是测量鸟苷神经调节和保护过程中信号动力学的一种有价值的方法。
