Dengler Adam K, McCarty Gregory S
Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, USA.
J Electroanal Chem (Lausanne). 2013 Mar 15;693:28-33. doi: 10.1016/j.jelechem.2013.01.022. Epub 2013 Feb 4.
The electrochemical detection of neurotransmitters has centered on fast scan cyclic voltammetry (FSCV) due to its temporal resolution, sensitivity and chemical selectivity. FSCV is a differential technique that records phasic (second-to-second) changes in the concentration of electroactive neurotransmitters such as dopamine (DA). To isolate the currents due to fluctuations in analyte concentration, in other words to make these phasic measurements, requires the subtraction of a large background current. The subtraction of this background and its volatility renders FSCV unable to determine background or slowly varying concentrations of electroactive analytes. However, there is still a need to readily determine the background and slowly changing concentrations of electroactive analytes in tissue. For example, the background concentrations of DA vary throughout the brain and can affect the dynamics of dopaminergic systems. So, this report presents a microfabricated electrochemical sensor for measuring background and slowly changing concentrations of DA with the selectivity and sensitivity of FSCV. The sensor is comprised of two microfabricated microelectrodes which are spaced 8 μm apart. Varying the applied potential of the outer electrode manipulates the local concentration of electroactive species including concentration at the inner electrode. These changes are measured at the inner electrode using FSCV. The resulting signal with calibration can determine the background and slowly changing concentration of DA with the selectivity and sensitivity of FSCV. In this study the background of DA is determined using this sensor. The DA signal is shown to be the result of adsorption/desorption at the outer electrode. Interference from ascorbate on the DA signal is shown to be minimal for this approach.
由于其时间分辨率、灵敏度和化学选择性，神经递质的电化学检测主要集中在快速扫描循环伏安法（FSCV）上。FSCV是一种差分技术，可记录电活性神经递质（如多巴胺，DA）浓度的阶段性（每秒）变化。为了分离由于分析物浓度波动而产生的电流，换句话说，为了进行这些阶段性测量，需要减去一个大的背景电流。减去这个背景及其波动性使得FSCV无法确定电活性分析物的背景或缓慢变化的浓度。然而，仍然需要能够方便地确定组织中电活性分析物的背景和缓慢变化的浓度。例如，DA的背景浓度在整个大脑中各不相同，并且会影响多巴胺能系统的动态。因此，本报告展示了一种微制造的电化学传感器，用于以FSCV的选择性和灵敏度测量DA的背景和缓慢变化的浓度。该传感器由两个微制造的微电极组成，它们之间的间距为8μm。改变外电极施加的电位会操纵包括内电极处浓度在内的电活性物质的局部浓度。这些变化在内电极处使用FSCV进行测量。经过校准后得到的信号可以以FSCV的选择性和灵敏度确定DA的背景和缓慢变化的浓度。在本研究中，使用该传感器确定了DA的背景。DA信号被证明是外电极上吸附/解吸的结果。对于这种方法，抗坏血酸对DA信号的干扰被证明是最小的。
