Department of Chemistry, Virginia Commonwealth University, 1001 W. Main Street, Richmond, Virginia 23284, United States.
Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, Florida 33431, United States.
Anal Chem. 2023 Aug 22;95(33):12557-12564. doi: 10.1021/acs.analchem.3c02926. Epub 2023 Aug 11.
The self-monitoring of electrolytes using a small volume of capillary blood is needed for the management of many chronic diseases. Herein, we report an ionophore-based colorimetric sensor for electrolyte measurements in a few microliters of blood. The sensor is a pipet microtip preloaded with a segment of oil (plasticizer) containing a pH-sensitive chromoionophore, a cation exchanger, and an ionophore. The analyte is extracted from the sample into the oil via a mixing protocol controlled by a stepper motor. The oil with an optimized ratio of sensing chemicals shows an unprecedentedly large color response for electrolytes in a very narrow concentration range that is clinically relevant. This ultrahigh sensitivity is based on an exhaustive response mode with a novel mechanism for defining the lower and higher limits of detection. Compared to previous optodes and molecular probes for ions, the proposed platform is especially suitable for at-home blood electrolyte measurements because (1) the oil sensor is interrogated independent of the sample and therefore works for whole blood without requiring plasma separation; (2) the sensor does not need individual calibration as the consistency between liquid sensors is high compared to solid sensors, such as ion-selective electrodes and optodes; and (3) the sensing system consisting of a disposable oil sensor, a programmed stepper motor, and a smartphone is portable, cost-effective, and user-friendly. The accuracy and precision of Ca sensors are validated in 51 blood samples with varying concentrations of total plasma Ca. Oil sensors with an ultrasensitive response can also be obtained for other ions, such as K.
自我监测电解质使用毛细管血液的小体积是需要管理的许多慢性疾病。在此，我们报告了一种基于离子载体的比色传感器，用于测量几微升血液中的电解质。该传感器是一个移液器微尖端，预先加载有一段含有 pH 敏感显色离子载体、阳离子交换剂和离子载体的油（增塑剂）。分析物通过由步进电机控制的混合方案从样品中提取到油中。油中含有最佳比例的传感化学品，对临床相关的非常窄浓度范围内的电解质表现出前所未有的大颜色响应。这种超高灵敏度基于一种详尽的响应模式，具有一种新颖的机制来定义检测限的下限和上限。与以前用于离子的光电二极管和分子探针相比，所提出的平台特别适合家庭用血液电解质测量，因为 (1) 油传感器与样品无关，因此无需进行血浆分离即可用于全血；(2) 由于与固体传感器（如离子选择性电极和光电二极管）相比，液体传感器之间的一致性较高，因此传感器不需要单独校准；(3) 由一次性油传感器、程控步进电机和智能手机组成的传感系统便携、经济实惠且易于使用。在 51 个具有不同总血浆 Ca 浓度的血液样本中验证了 Ca 传感器的准确性和精密度。对于其他离子，如 K，也可以获得具有超灵敏响应的油传感器。
