Suppression of Ionic Doping by Molecular Dopants in Conjugated Polymers for Improving Specificity and Sensitivity in Biosensing Applications
Suppression of Ionic Doping by Molecular Dopants in Conjugated Polymers for Improving Specificity and Sensitivity in Biosensing Applications
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通过共轭聚合物中的分子掺杂剂抑制离子掺杂，提高生物传感应用的特异性和灵敏度
DOI：
10.1021/acsami.0c11125
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发表时间：
2020
影响因子：
9.5
通讯作者：
Katz, Howard E.
中科院分区：
文献类型：
--
作者：
Jang, Hyun-June;Song, Yunjia;Wagner, Justine;Katz, Howard E.
共轭聚合物中的离子掺杂效应往往导致非特异性信号和生物电子传感的低选择性。利用远栅场效应晶体管表征了聚3-己基噻吩基(P3HT)和酸功能化聚[3-(3-羧丙基)噻吩基-2，5-二基](PT-COOH)中的分子和离子掺杂，发现2，3，5，6-tetrafluoro-7，7，8，8-tetracyanoquinodimethane(F4TCNQ)依次掺杂P3HT可以抑制质子掺杂对P3HT界面电势的影响。具体地说，掺杂P3HT：F4TCNQ后，P3HT的本征pH敏感性(在pH 3~9范围内为18 mV/pH)被完全消散。然而，与纯PT-COOH(30 mV/pH)相比，F4TCNQ顺序掺杂反而提高了酸功能化聚噻吩PT-COOH的pH敏感性(40 mV/pH)。较强的F4TCNQ掺杂削弱了限制COOH活性的聚噻吩类主链和侧链之间的相互作用，留下了暴露在水溶液中的响应COOH基团。一种较弱的掺杂剂四氰乙烯(TCNE)的顺序掺杂降低了PT-COOH的pH敏感性(21 mV/pH)，这支持了这一点。因此，掺杂一方面可以稳定非极性共轭聚合物对pH引起的波动，另一方面可以激活COOH侧链对pH引起的响应。
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.