Berkheimer Zachary A, Tahir Anum, Nordin Gregory P, Paixão Thiago R L C, Woolley Adam T, do Nascimento Guida H M, de Araujo William R, Pradela-Filho Lauro A
Department of Chemistry and Biochemistry, Brigham Young University, 84602, Provo, UT, USA.
Department of Electrical and Computer Engineering, Brigham Young University, 84602, Provo, UT, USA.
Biosens Bioelectron. 2025 Jun 15;278:117390. doi: 10.1016/j.bios.2025.117390. Epub 2025 Mar 24.
Versatile electrodes were templated into poly (methyl methacrylate) (PMMA) molds with a 3D printing pen and commercial carbon black filament. The working electrodes (WE) were modified with Prussian Blue (PB), lactate oxidase (LOx)/chitosan solution, and Nafion. Under optimized modification conditions, a 3-electrode thermoplastic chip was integrated with paper-based analytical devices (μPADs). This integration was conducted by attaching a circular piece of paper to the 3-electrode thermoplastic chip, enclosing the system with a PMMA cover and clamps. The injections of the analyte solution were performed at the center of the μPADs, where the WE is positioned. The injections generated a radial flow during the analysis, eliminating the need for channels containing hydrophobic barriers to constrain the solution. This system also allows sequential/multiple injections of analyte solution, providing rapid responses in peak format. The μPADs were initially characterized with a food dye solution and ferricyanide as a redox probe. Increasing the pore size of the paper substrates increased the flow rate of the μPADs, providing sharper and more intense transient signals. In addition, increasing the injection volume produced broader peaks, also limiting the number of injections. The proposed system provided a linear range from 0.5 to 4 mmol L lactate. Requiring only 2 μL of the sample, the analytical applicability of the μPADs was further demonstrated for lactate determination through discrete sampling of real sweat. Therefore, this work brings a straightforward approach to fabricating μPADs for lactate quantification, opening possibilities for new sensing applications demanding sample volumes as small as a few μL.
使用3D打印笔和商用炭黑长丝将多功能电极模板化到聚甲基丙烯酸甲酯（PMMA）模具中。工作电极（WE）用普鲁士蓝（PB）、乳酸氧化酶（LOx）/壳聚糖溶液和Nafion进行修饰。在优化的修饰条件下，将三电极热塑性芯片与纸基分析装置（μPAD）集成。这种集成是通过将一张圆形纸附着到三电极热塑性芯片上，并用PMMA盖和夹具封闭系统来实现的。分析物溶液的注入在μPAD的中心进行，WE位于该中心。注入过程在分析过程中产生径向流，无需包含疏水屏障的通道来限制溶液。该系统还允许顺序/多次注入分析物溶液，以峰的形式提供快速响应。μPAD最初用食用染料溶液和铁氰化物作为氧化还原探针进行表征。增加纸质基底的孔径会提高μPAD的流速，提供更尖锐、更强烈的瞬态信号。此外，增加注入体积会产生更宽的峰，也会限制注入次数。所提出的系统提供了0.5至4 mmol/L乳酸的线性范围。仅需2 μL样品，通过对真实汗液的离散采样，进一步证明了μPAD在乳酸测定中的分析适用性。因此，这项工作为制造用于乳酸定量的μPAD带来了一种直接的方法，为需要几微升小样品体积的新传感应用开辟了可能性。
