Additive Manufacturing towards the Fabrication of Greener Electrochemical Sensors for Antioxidants

Additive manufacturing is an emerging tool that has contributed to the sustainable fabrication of devices in several areas based on the concept of “zero waste”. Considering extrusion-based manufacturing (or 3D printing), polylactic acid (PLA) has been highlighted due to its biodegradability, obtention from renewable sources, and compatibility for 3D printing. Composites of PLA with conducting fillers, such as carbon-black (CB/PLA), are commercially-available and compatible with extrusion-based 3D printers and 3D pen. Herein, we investigate the electrochemical behavior of several antioxidant species (catechol, hydroquinone, propyl-gallate, octyl-gallate, dopamine, gallic acid and pyrogallol (PY)) on 3D-printed electrodes. Experiments by cyclic voltammetry demonstrated that electrochemical surface treatment in NaOH aqueous solution is an important strategy to improve the response of all antioxidants. Thus, PY was selected to evaluate the analytical performance of the proposed 3D-printed sensor. For this, a fast and simple method using batch-injection analysis with amperometric detection (BIA-AD) has been developed, which showed a limit of detection of 0.15 µmol L-1, wide linear range (0.5 to 300 µmol L-1), good precision (relative standard deviation (RSD) < 3.4%) and selectivity. This method was applied in biodiesel samples, after dilution (400-fold) in electrolyte. Recovery percentages ranging from 82 to 119% attested absence of matrix effect and good accuracy.

增材制造（Additive Manufacturing）是一项新兴技术，依托“零废弃”理念，已在多个领域推动了器件的可持续制备。针对挤出式增材制造（又称3D打印），聚乳酸（PLA）因具备生物可降解性、可由可再生资源获取且适配3D打印工艺而广受关注。添加导电填料的聚乳酸复合材料，如炭黑/聚乳酸（CB/PLA）复合材料，已实现商业化生产，且可兼容挤出式3D打印机与3D绘图笔。

本文中，我们探究了7种抗氧化物质——儿茶酚、对苯二酚、没食子酸丙酯、没食子酸辛酯、多巴胺、没食子酸与焦性没食子酸（PY）——在3D打印电极上的电化学行为。循环伏安法（Cyclic Voltammetry）实验结果表明，在氢氧化钠水溶液中开展电化学表面处理，是提升所有待测抗氧化物质电化学响应信号的有效策略。据此选取焦性没食子酸（PY），用以评估所构建的3D打印传感器的分析性能。

为此，我们开发了一种结合安培检测的批量注射分析法（BIA-AD），该方法快速简便，其检出限为0.15 µmol·L⁻¹，线性范围宽（0.5~300 µmol·L⁻¹），精密度良好（相对标准偏差（RSD）<3.4%）且选择性优异。将该方法应用于经电解质400倍稀释后的生物柴油样品检测，回收率介于82%~119%之间，证实无基质效应且方法准确度良好。