Highly Sensitive and Selective Biosensors Based on Organic Transistors Functionalized with Cucurbit[6]uril Derivatives

Biosensors based on a field‐effect transistor platform allow continuous monitoring of biologically active species with high sensitivity due to the amplification capability of detected signals. To date, a large number of sensors for biogenic substances have used high‐cost enzyme immobilization methods. Here, highly sensitive organic field‐effect transistor (OFET)‐based sensors functionalized with synthetic receptors are reported that can selectively detect acetylcholine (ACh⁺), a critical ion related to the delivery of neural stimulation. A cucurbit6]uril (CB6]) derivative, perallyloxyCB6] ((allyloxy)₁₂CB6], AOCB6]), which is soluble in methanol but insoluble in water, has been solution‐deposited as a selective sensing layer onto a water‐stable p‐channel semiconductor, 5,5′‐bis‐(7‐dodecyl‐9H‐fluoren‐2‐yl)‐2,2′‐bithiophene layer. The OFET‐based sensors exhibit a detection limit down to 1 × 10^–12 m of ACh⁺, which is six orders of magnitude lower than that of ion‐selective electrode‐based sensors. Moreover, these OFET‐based sensors show highly selective discrimination of ACh⁺ over choline (Ch⁺). The findings demonstrate a viable method for the fabrication of OFET‐based biosensors with high sensitivity and selectivity, and allow for practical applications of OFETs as high‐performance sensors for biogenic substances.