A novel platform of microfluidic paper-based analytical devices (μPADs) for dual detection of bisphenol A (BPA), a model analyte, was fabricated using an electronic digital plotter to create the stacked layer of μPADs and generate the lateral-flow channel without using an external pump. Two detection techniques, including electrochemical detection and laser desorption ionization mass spectrometric detection (LDI-MS), were used complementarily to improve the precision in the detection of BPA. The fluid sample was delivered to both detection zones by the capillary action, automatically generated from the fabricated microfluidic device. For an electrochemical sensor, two ballpoint pens filled with silver nanoparticles (AgNPs) and multiwall carbon nanotube (MWCNT) ink were used to print onto the paper with a contact printing method using a digital plotter. To further improve the sensitivity, zinc oxide (ZnO) was used to modify both electrochemical and LDI-MS detection zones. For BPA detection, high electrocatalytic properties and strong UV absorption of ZnO promote the electron transfer in the electrochemical sensor and ionization efficiency in LDI-MS with low interferences compared with a conventional organic matrix. Under optimal conditions, this platform showed a dual detection capability for BPA with a detection limit of 0.35 μM for electrochemical detection and with an ultralow detection limit of 0.01 pM for LDI-MS. This novel platform might be very useful for trace analyses requiring high precision detection of various analytes.

中文翻译：

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基于3D纸的微流体设备：双酚A的新型双重检测平台。

使用电子数字绘图仪制造了用于双检测双酚A（BPA）（一种模型分析物）的新型微流体纸质分析设备（μPAD）平台，以创建μPAD的堆叠层并生成横向流通道，而无需使用一个外部泵。互补地使用了两种检测技术，包括电化学检测和激光解吸电离质谱检测（LDI-MS），以提高BPA的检测精度。流体样品通过毛细作用输送到两个检测区域，毛细作用是由制造的微流体装置自动生成的。对于电化学传感器，使用填充有银纳米颗粒（AgNPs）和多壁碳纳米管（MWCNT）墨水的两支圆珠笔，使用数字绘图仪通过接触印刷法在纸上进行印刷。为了进一步提高灵敏度，氧化锌（ZnO）用于修饰电化学和LDI-MS检测区。对于BPA检测，与常规有机基质相比，ZnO的高电催化性能和强紫外线吸收性可促进电化学传感器中的电子转移和LDI-MS中的电离效率，且干扰较小。在最佳条件下，该平台显示出对BPA的双重检测功能，电化学检测的检测限为0.35μM，LDI-MS的检测限为0.01 pM的超低。