Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1111 Budapest, Hungary.
Int J Mol Sci. 2021 Sep 29;22(19):10552. doi: 10.3390/ijms221910552.
Molecularly imprinted polymers have been shown to be useful in competitive biomimetic binding assays. Recent developments in materials science have further enhanced the capabilities of imprinted polymers. Binding assays, biological and biomimetic alike, owe their usefulness to their selectivity. The selectivity of competitive binding assays has been characterized with the cross-reactivity, which is usually expressed as the ratio of the measured IC50 concentration values of the interferent and the analyte, respectively. Yet this cross-reactivity is only a rough estimate of analytical selectivity. The relationship between cross-reactivity and analytical selectivity has apparently not been thoroughly investigated. The present work shows that this relationship depends on the underlying model of the competitive binding assay. For the simple but widely adopted model, where analyte and interferent compete for a single kind of binding site, we provide a simple formula for analytical selectivity. For reasons of an apparent mathematical problem, this formula had not been found before. We also show the relationship between analytical selectivity and cross-reactivity. Selectivity is also shown to depend on the directly measured quantity, e.g., the bound fraction of the tracer. For those cases where the one-site competitive model is not valid, a practical procedure is adopted to estimate the analytical selectivity. This procedure is then used to analyze the example of the competitive two-site binding model, which has been the main model for describing molecularly imprinted polymer behavior. The results of this work provide a solid foundation for assay development.
分子印迹聚合物已被证明在竞争性仿生结合分析中很有用。材料科学的最新发展进一步提高了印迹聚合物的能力。结合分析，无论是生物的还是仿生的，都因其选择性而有用。竞争性结合分析的选择性已通过交叉反应来表征，通常表示为干扰物和分析物的测量 IC50 浓度值之比。然而，这种交叉反应只是分析选择性的粗略估计。交叉反应与分析选择性之间的关系显然尚未得到彻底研究。本工作表明，这种关系取决于竞争性结合分析的基础模型。对于简单但广泛采用的模型，其中分析物和干扰物竞争单一类型的结合位点，我们提供了分析选择性的简单公式。由于明显的数学问题，这个公式之前没有被发现。我们还展示了分析选择性与交叉反应之间的关系。选择性也取决于直接测量的量，例如示踪剂的结合分数。对于那种一结合位点竞争模型不成立的情况，我们采用了一种实用的程序来估计分析选择性。然后，该程序用于分析竞争性双结合模型的实例，该模型一直是描述分子印迹聚合物行为的主要模型。这项工作的结果为分析开发提供了坚实的基础。
