Ionic doping effects in conjugated polymers often cause nonspecific signaling and a low selectivity of bioelectronic sensing. Using remote-gate field-effect transistor characterization of molecular and ionic doping in poly(3-hexylthiophene) (P3HT) and acid-functionalized polythiophene, poly[3-(3-carboxypropyl) thiophene-2,5-diyl] (PT-COOH), we discovered that proton doping effects on the interfacial potential occurring in P3HT could be suppressed by sequentially doping P3HT by 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). To be specific, intrinsic pH sensitivity shown by pure P3HT (18 mV/pH in a range from pH 3 to 9) was fully dissipated for doped P3HT:F4TCNQ. However, F4TCNQ sequential doping instead increases pH sensitivity of acid-functionalized polythiophene, PT-COOH (40 mV/pH), compared to that of a pure PT-COOH (30 mV/pH). Interactions between polythiophene backbone and side chains, which constrain the activity of COOH, are weakened by stronger F4TCNQ doping leaving behind responsive COOH groups exposed to aqueous solutions. This is supported by the reduced pH sensitivity of PT-COOH sequentially doped by a weaker dopant, tetracyanoethylene (TCNE) (21 mV/pH). Thus, doping is shown to stabilize a nonpolar conjugated polymer to pH-induced fluctuations on one hand, and to activate a COOH side chain to pH-induced response on the other.

中文翻译：

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通过分子掺杂剂抑制共轭聚合物中的离子掺杂，以提高生物传感应用中的特异性和敏感性。

共轭聚合物中的离子掺杂效应通常会导致非特异性信号传导和生物电子传感的低选择性。使用远程栅场效应晶体管表征聚（3-己基噻吩）（P3HT）和酸官能化聚噻吩，聚[3-（3-羧丙基）噻吩-2,5-二基]（PT- COOH），我们发现通过依次用2,3,5,6-四氟-7,7,8,8-四氰基喹二甲烷（F4TCNQ）掺杂P3HT，可以抑制质子掺杂对P3HT中发生的界面电势的影响。具体而言，对于掺杂的P3HT：F4TCNQ，完全消除了纯P3HT（18 mV / pH在3至9的范围内）所显示的固有pH敏感性。但是，与纯PT-COOH（30 mV / pH）相比，F4TCNQ顺序掺杂可提高酸官能化聚噻吩PT-COOH（40 mV / pH）的pH敏感性。较强的F4TCNQ掺杂削弱了聚噻吩骨架和侧链之间的相互作用，从而抑制了COOH的活性，从而使暴露在水溶液中的响应性COOH基团消失了。依次由较弱的掺杂剂四氰基乙烯（TCNE）（21 mV / pH）依次掺杂的PT-COOH降低了pH敏感性，从而支持了这一点。因此，显示出掺杂一方面使非极性共轭聚合物稳定于pH引起的波动，另一方面使COOH侧链活化以引起pH引起的响应。