Ataide Vanessa N, Ameku Wilson A, Bacil Raphael P, Angnes Lúcio, de Araujo William R, Paixão Thiago R L C
Department of Fundamental Chemistry, Institute of Chemistry, São Paulo University-USP São Paulo SP 05508-900 Brazil
Department of Analytical Chemistry, Institute of Chemistry, State University of Campinas-UNICAMP Campinas SP 13083-970 Brazil.
RSC Adv. 2021 Jan 5;11(3):1644-1653. doi: 10.1039/d0ra08874a. eCollection 2021 Jan 4.
Electrochemical Paper-based Analytical Devices (ePADs) are an alternative to traditional portable analytical techniques due to features such as low-cost, easy surface modification with different materials, and high sensitivity. A fast and simple method to fabricate enhanced ePADs using pencil-drawing which involves the CO laser treatment of the carbon surface deposited on paper is described. The electrochemical performances of the devices were evaluated using cyclic voltammetry (CV) with different redox probes and electrochemical impedance spectroscopy (EIS). The electrochemical results show that a treated surface presents a lower resistance to charge transfer and changes the approach of the probe and the overlap of its orbitals with the electrode. To investigate the effects of the laser treatment process, chemical and structural characteristics were evaluated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. These results indicated that laser treatment promoted the restoration of carbon-carbon double bonds and removed a thin layer of nanodebris present in commercial pencils, resulting in an improvement of the electrochemical kinetics. As a proof-of-concept, the Pencil-Drawing Electrode (PDE) was used for the detection and quantification of furosemide (FUR) in a sample of synthetic urine, exhibiting a limit of detection (LOD) of 2.4 × 10 mol L. The percentages of recovery of the FUR added to the samples A and B were 95% and 110%, respectively. The analysis using CO laser-treated PDE resulted in a fast, simple, and reliable method for this doping agent.
基于纸的电化学分析装置（ePADs）因其低成本、易于用不同材料进行表面改性以及高灵敏度等特点，成为传统便携式分析技术的一种替代方案。本文描述了一种使用铅笔绘图制造增强型ePADs的快速简便方法，该方法涉及对沉积在纸上的碳表面进行CO激光处理。使用不同的氧化还原探针通过循环伏安法（CV）和电化学阻抗谱（EIS）对装置的电化学性能进行了评估。电化学结果表明，经过处理的表面对电荷转移的电阻较低，并改变了探针的接近方式及其轨道与电极的重叠情况。为了研究激光处理过程的影响，使用扫描电子显微镜（SEM）、X射线光电子能谱（XPS）和拉曼光谱对化学和结构特征进行了评估。这些结果表明，激光处理促进了碳 - 碳双键的恢复，并去除了商业铅笔中存在的一层薄纳米碎片，从而改善了电化学动力学。作为概念验证，铅笔绘图电极（PDE）用于检测和定量合成尿液样本中的速尿（FUR），检测限（LOD）为2.4×10 mol/L。添加到样品A和B中的FUR的回收率分别为95%和110%。使用CO激光处理的PDE进行分析为这种掺杂剂提供了一种快速、简单且可靠的方法。
