Abstract The homemade production of carbon screen-printed electrodes (C-SPEs) with a three‑carbon electrode system is reported, along with its application in electrochemical sensing. It is highlighted herein as main novelty that a simple carbon ink may be employed in the preparation of the 3-electrode system, including the pseudo-reference electrode, thereby avoiding the addition of silver or other suitable metal and simplify the construction of such devices, reducing costs and time. Screen-printed technology was employed to produce the 3-electrodes and the corresponding electrical paths. This was achieved by the manual application of a commercial carbon ink into a polyvinyl chloride (PVC) substrate allowing the production of > 20 SPEs. The optimization of the SPE assembly was made by univariate mode, until the best electrical features of the electrode-solution interface were achieved. Several electrochemical techniques were used for this purpose, namely cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Raman Spectroscopy and Thermogravimetric Analysis (TGA) were also used for materials and electrode surface characterization. The usefulness of such devices was tested by modifying the working electrode with a sensing layer for microRNA-107, a potential biomarker in Alzheimer's Disease (AD). For this purpose, the surface was functionalized with carboxylic groups, activated by carbodiimide reaction and bound to a suitable oligonucleotide probe containing the complementary sequence. Finally, the microRNA-107 sequence hybridized with its probe, proving the efficiency of the C-SPEs in electrochemical sensing. Overall, this study brings into light the possibility of preparing simple homemade electrodes with a 3‑carbon electrode system that stands out by the low cost, disposability and versatility of the presented platform, holding a great potential for application in point-of-care devices using electrochemical sensing.

中文翻译：

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用于电化学传感的自制 3 碳电极系统：在 microRNA 检测中的应用

摘要 报道了采用三碳电极系统自制碳丝网印刷电极 (C-SPE) 及其在电化学传感中的应用。在此强调的主要新颖之处在于，可以在 3 电极系统（包括伪参比电极）的制备中使用简单的碳墨，从而避免添加银或其他合适的金属并简化此类装置的构造，减少成本和时间。采用丝网印刷技术来生产 3 电极和相应的电路径。这是通过将商业碳墨水手动应用到聚氯乙烯 (PVC) 基材上实现的，允许生产 > 20 SPE。SPE 组件的优化是通过单变量模式进行的，直到达到电极-溶液界面的最佳电气特性。为此使用了几种电化学技术，即循环伏安法 (CV)、方波伏安法 (SWV) 和电化学阻抗谱 (EIS)。拉曼光谱和热重分析 (TGA) 也用于材料和电极表面表征。通过使用 microRNA-107（阿尔茨海默病 (AD) 的潜在生物标志物）的传感层修改工作电极来测试此类设备的实用性。为此，表面用羧基官能化，通过碳二亚胺反应活化并结合到含有互补序列的合适的寡核苷酸探针。最后，microRNA-107 序列与其探针杂交，证明了 C-SPE 在电化学传感中的效率。总体而言，这项研究揭示了使用 3 碳电极系统制备简单自制电极的可能性，该系统以所呈现平台的低成本、一次性和多功能性而著称，在即时护理设备中具有巨大的应用潜力使用电化学传感。