Calcium ions are crucial in numerous physiological processes, and their precise measurement is important for many clinical diagnostics and therapeutic interventions. Traditional detection methods, such as atomic absorption spectroscopy, cannot meet clinical requirements, as they measure total calcium instead of the clinically relevant ionized form (Ca²⁺). Ion-selective electrodes (ISEs) provide a convenient, accurate, and specific method for Ca²⁺ determination. Here, two isomeric calcium ionophores (R,R)-calcium ionophore I, also known as ETH 1001, and (R,S)-calcium ionophore I are synthesized and characterized for the analysis of whole blood samples with the Eaglenos blood gas analyzer (model: EG-i30) equipped with test cartridges containing screen-printed electrodes. (R,R)-Calcium ionophore I demonstrated excellent precision in whole blood samples, achieving an average bias of −2.2% compared with the available gold standard. On the other hand, the (R,S) isomer was not satisfactory, exhibiting a bias of up to −20%. Ion transfer voltammetry at thin membrane films gave information about the complex stoichiometry, complex formation constants, and ion selectivity for the two isomeric ionophores. A stoichiometry of the Ca²⁺-ionophore complex was confirmed to be 1:2 for both ionophores, while the (R,R) isomer gave 3.4 orders of magnitude larger complex formation constants and a modestly higher selectivity. While these data are valuable, the poor performance of membranes containing the (R,S) isomer is not directly apparent from the fundamental binding characteristics. It may be caused by interference from lipophilic blood sample components and/or surface adsorption processes, suggesting that routine selectivity characterizations of membranes containing selective ionophores are insufficient to assess their usefulness in clinical applications.

中文翻译：

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ETH 1001 在聚合物离子选择性膜中异构钙离子载体的络合行为和临床评价


钙离子在许多生理过程中至关重要，它们的精确测量对于许多临床诊断和治疗干预非常重要。传统的检测方法，如原子吸收光谱法，无法满足临床要求，因为它们测量的是总钙，而不是临床相关的电离形式 （Ca²⁺）。离子选择性电极 （ISE） 为 Ca²⁺ 测定提供了一种方便、准确和特异的方法。在这里，合成了两个异构体钙离子载体 （R，R）-钙离子载体 I（也称为 ETH 1001）和 （R，S）-钙离子载体 I，用于使用 Eaglenos 血气分析仪（型号：EG-i30）分析全血样品，该分析仪配备了包含丝网印刷电极的测试盒。（R，R）-钙离子载体 I 在全血样品中表现出优异的精密度，与现有金标准品相比，平均偏差为 -2.2%。另一方面，（R，S） 异构体并不令人满意，表现出高达 -20% 的偏差。薄膜上的离子转移伏安法提供了有关两种异构离子载体的复合物化学计量、复合物形成常数和离子选择性的信息。Ca²⁺-离子载体复合物的化学计量被证实为两种离子载体的 1：2，而 （R，R） 异构体的复合物形成常数大 3.4 个数量级，选择性略高。虽然这些数据很有价值，但从基本结合特性来看，含有 （R，S） 异构体的膜性能不佳并不直接明显。 它可能是由亲脂性血液样品成分和/或表面吸附过程的干扰引起的，这表明含有选择性离子载体的膜的常规选择性表征不足以评估它们在临床应用中的有用性。