Soulis Dionysios, Mermiga Electra, Pagkali Varvara, Trachioti Maria, Kokkinos Christos, Prodromidis Mamas, Economou Anastasios
Laboratory of Analytical Chemistry, Department of Chemistry, University of Athens, Athens 157 71, Greece.
Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina, Ioannina 45110, Greece.
Anal Chem. 2025 Jan 21;97(2):1457-1464. doi: 10.1021/acs.analchem.4c06982. Epub 2025 Jan 9.
This work describes fully integrated multifolding electrochemical paper-based devices (ePADs) for enhanced multiplexed voltammetric determination of heavy metals (Zn(II), Cd(II), and Pb(II)) using tunable passive preconcentration. The paper devices integrate five circular sample preconcentration layers and a 3-electrode electrochemical cell. The hydrophobic barriers of the devices are drawn by pen-plotting with hydrophobic ink, while the electrodes are deposited by screen-printing. The devices exploit the wicking ability of cellulose paper to perform passive preconcentration of the target analytes, resulting in a ∼6-fold signal enhancement. For this purpose, drops of the sample are placed at the five sample pads of the preconcentration layers, the device is folded, and the target metals are eluted in a vertical-flow mode to the electrochemical cell, where they are measured directly by anodic stripping voltammetry (ASV). The working electrode of the ePADs is bulk-modified with bismuth citrate; during the ASV measurements, the bismuth precursor is converted to nanodomains of metallic bismuth at the surface of the working electrode. By combining the triplex signal amplification through passive preconcentration, electrochemical preconcentration, and judicious working electrode modification with generated bismuth nanoparticles, ultrasensitive and multiplexed heavy metal assays can be achieved. Due to their high degree of integration, low cost, easy and fast fabrication, and sensitivity, the multifolding ePADs are particularly suitable for on-site heavy metals' monitoring applications.
这项工作描述了一种完全集成的多重折叠式电化学纸质器件（ePADs），用于通过可调谐被动预富集增强对重金属（锌（II）、镉（II）和铅（II））的多重伏安测定。纸质器件集成了五个圆形样品预富集层和一个三电极电化学池。器件的疏水屏障通过用疏水墨水笔绘绘制，而电极则通过丝网印刷沉积。这些器件利用纤维素纸的毛细作用对目标分析物进行被动预富集，从而使信号增强约6倍。为此，将样品滴放在预富集层的五个样品垫上，折叠器件，目标金属以垂直流动模式洗脱到电化学池中，在那里通过阳极溶出伏安法（ASV）直接进行测量。ePADs的工作电极用柠檬酸铋进行整体修饰；在ASV测量过程中，铋前体在工作电极表面转化为金属铋的纳米域。通过将被动预富集、电化学预富集以及通过生成铋纳米颗粒进行明智的工作电极修饰所实现的三重信号放大相结合，可以实现超灵敏和多重重金属检测。由于其高度集成、低成本、易于快速制造以及灵敏度高，多重折叠式ePADs特别适用于现场重金属监测应用。
