RESPONSE MECHANISM OF POLYMER MEMBRANE-BASED POTENTIOMETRIC POLYION SENSORS
RESPONSE MECHANISM OF POLYMER MEMBRANE-BASED POTENTIOMETRIC POLYION SENSORS
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DOI：
10.1021/ac00086a009
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发表时间：
1994-07-15
影响因子：
7.4
通讯作者：
MEYERHOFF, ME
中科院分区：
文献类型：
--
作者：
FU, B;BAKKER, E;MEYERHOFF, ME
建立了聚合物膜电极对聚阴离子肝素敏感的电位响应机理。基于转运和浸提研究，肝素响应归因于样品/膜界面相界电位的非平衡变化。虽然仅在非常长的平衡时间（> 20 h）后才获得低肝素浓度的真实平衡聚离子响应，但产生预期的能斯特响应斜率< 1 mV/decade，观察到对临床相关肝素浓度的较大且可重现的EMF响应（类似于10（-7）M）在典型的测量周期（2-5分钟）归因于一个稳定的-状态动力学过程由聚离子到聚合物膜的表面和进入聚合物膜的本体的通量限定。描述这种非平衡响应的模型。利用该模型，聚合物膜组成的独特性（例如，非常低的增塑剂含量、严格控制的阳离子位点浓度等）获得分析有用的肝素反应所需的时间变得清楚。讨论了传感器的实际工作条件和局限性。为了支持所提出的稳态模型的一般性，相应的电动势响应数据的一个新开发的膜电极敏感的聚阳离子蛋白（鱼精蛋白）。结果表明，鱼精蛋白响应膜电极似乎通过与肝素传感系统完全相同的动力学机制来操作。
The potentiometric response mechanism of a previously reported polymer membrane-based electrode sensitive to the polyanion heparin is established. Based on transport and extraction studies, the heparin response is attributed to a nonequilibrium change in the phase boundary potential at the sample/membrane interface. While true equilibrium polyion response, obtained for low heparin concentrations only after very long equilibration times (> 20 h), yields the expected Nernstian response slope of < 1 mV/decade, the observed large and reproducible EMF response to clinically relevant heparin concentrations (similar to 10(-7) M) during typical measurement periods (2-5 min) is ascribed to a steady-state kinetic process defined by the flux of the polyion both to the surface and into the bulk of the polymer membrane. A model describing this nonequilibrium response is presented. With this model, the uniqueness of the polymer membrane composition (e.g., very low plasticizer content, strictly controlled cationic site concentration, etc.) required to achieve analytically useful heparin response becomes clear. Practical working conditions and limitations of the sensor are discussed. To support the generality of the steady-state model proposed, corresponding EMF response data for a newly developed membrane electrode sensitive to a polycationic protein (protamine) are also presented. It is shown that the protamine-responsive membrane electrode appears to operate via the exact same kinetic mechanism as the heparin sensing system.