Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras 2780-157, Portugal.
Anal Chem. 2024 Oct 15;96(41):16244-16251. doi: 10.1021/acs.analchem.4c03150. Epub 2024 Oct 1.
The use of miniaturized probes opens a new dimension in the analysis of (bio)chemical processes, enabling the possibility to perform measurements with local resolution. In addition, multiparametric measurements are highly valuable for a holistic understanding of the investigated process. Therefore, different strategies have been suggested for simultaneous local measurements of various parameters. Electroanalytical methods are a powerful strategy in this direction. However, they have been mainly restricted to coupling concurrent independent measurements with different miniaturized probes. Here, we present an enzymatic microbiosensor for the simultaneous detection of O and pH. The sensing strategy is based on the pH-dependent bioelectrocatalytic process associated with O reduction at a gold microelectrode modified with a multicopper oxidase. After initial investigations of the bioelectrocatalytic reaction over gold macroelectrodes, the fabrication and characterization of micrometer-sized probes are presented. The microbioelectrode exhibits a linear current increase with O concentration extending to 17.2 mg L, with a sensitivity of (5.56 ± 0.13) nA L mg and a limit of detection of (0.5 ± 0.3) mg L. Moreover, a linear response allowing pH detection is obtained between pH 5.2 and 7.5 with a slope of -(47 ± 8) mV per pH unit. In addition, two proof-of-concept analytical examples are shown, demonstrating the capability of the developed sensing system for simultaneous local measurements of O and pH. Compared with other miniaturized probes reported before for simultaneous detection, our strategy stands out as the two investigated parameters are acquired from the very same measurement. This strategy greatly simplifies the analytical setup and for the first time provides truly simultaneous local detection in the micrometer scale.
微型探头的使用为（生物）化学过程的分析开辟了一个新的维度，使得能够以局部分辨率进行测量成为可能。此外，多参数测量对于全面理解所研究的过程非常有价值。因此，已经提出了不同的策略来同时进行各种参数的局部测量。电化学方法是朝这个方向的一个有力策略。然而，它们主要局限于将不同微型探头的并发独立测量进行耦合。在这里，我们提出了一种用于同时检测 O 和 pH 的酶微生物传感器。该传感策略基于与在金微电极上修饰的多铜氧化酶相关的 O 还原的 pH 依赖性生物电化学过程。在对金宏观电极上的生物电化学反应进行初步研究之后，提出了微米级探头的制造和表征。微生物电极表现出与 O 浓度呈线性增加的电流增加，延伸至 17.2 mg/L，灵敏度为（5.56 ± 0.13）nA/L/mg，检测限为（0.5 ± 0.3）mg/L。此外，在 pH 5.2 至 7.5 之间获得允许 pH 检测的线性响应，斜率为-(47 ± 8)mV/每 pH 单位。此外，还展示了两个概念验证分析示例，证明了所开发的传感系统用于同时进行局部 O 和 pH 测量的能力。与以前报道的用于同时检测的其他微型探头相比，我们的策略的突出之处在于所研究的两个参数是从同一测量中获得的。该策略大大简化了分析设置，并首次在微米级范围内提供真正的同时局部检测。
