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）是一种依托“零浪费”理念的新兴技术，已在多个领域推动了器件的可持续制备。针对基于挤出成型的制造工艺（或称3D打印），聚乳酸（polylactic acid, PLA）凭借其可生物降解性、可再生原料来源以及适配3D打印的兼容性而备受关注。以炭黑（carbon-black, CB/PLA）等导电填料与聚乳酸复合得到的材料已实现商业化，且可兼容基于挤出成型的3D打印机与3D绘图笔。

本文研究了七种抗氧化剂——邻苯二酚、对苯二酚、没食子酸丙酯、没食子酸辛酯、多巴胺、没食子酸以及焦性没食子酸（PY）——在3D打印电极上的电化学行为。循环伏安法实验证实，在氢氧化钠水溶液中开展电化学表面处理，是提升所有抗氧化剂检测响应的关键策略。据此，我们选取焦性没食子酸（PY）来评估所构建的3D打印传感器的分析性能。为此，我们开发了一种快速简便的安培检测批量注射分析（batch-injection analysis with amperometric detection, BIA-AD）方法，该方法的检出限为0.15 μmol·L⁻¹，线性范围宽达0.5至300 μmol·L⁻¹，精密度良好（相对标准偏差（relative standard deviation, RSD）<3.4%）且选择性优异。将该方法经电解质稀释400倍后应用于生物柴油样品检测，回收率介于82%至119%之间，证实无基质效应且准确度优良。