ACS Sens. 2022 Sep 23;7(9):2537-2544. doi: 10.1021/acssensors.2c00229. Epub 2022 Jun 14.
Sensitivity and speed of detection are contradicting demands that profoundly impact the electrical sensing of molecular biomarkers. Although single-molecule sensitivity can now be achieved with single-nanotube field-effect transistors, these tiny sensors, with a diameter less than 1 nm, may take hours to days to capture the molecular target at trace concentrations. Here, we show that this sensitivity-speed challenge can be addressed using covalently functionalized double-wall CNTs that form many individualized, parallel pathways between two electrodes. Each carrier that travels across the electrodes is forced to take one of these pathways that are fully gated chemically by the target-probe binding events. This sensor design allows us to electrically detect Lyme disease oligonucleotide biomarkers directly at the physiological high-salt concentrations, simultaneously achieving both ultrahigh sensitivity (as low as 1 fM) and detection speed (<15 s). This unexpectedly simple strategy may open opportunities for sensor designs to broadly achieve instant detection of trace biomarkers and real-time probing of biomolecular functions directly at their physiological states.
灵敏度和检测速度是相互矛盾的需求，这对分子生物标志物的电感应产生了深远的影响。虽然现在可以通过单壁碳纳米管场效应晶体管实现单分子灵敏度，但这些直径小于 1nm 的微小传感器可能需要数小时到数天的时间才能在痕量浓度下捕获到分子靶标。在这里，我们展示了一种使用共价功能化的双壁 CNT 来解决这个灵敏度-速度挑战的方法，这些 CNT 在两个电极之间形成了许多独立的、平行的通路。每个穿过电极的载流子都被迫沿着这些通路之一移动，这些通路完全被目标探针结合事件在化学上进行了门控。这种传感器设计使我们能够直接在生理高盐浓度下对莱姆病寡核苷酸生物标志物进行电检测，同时实现超高灵敏度（低至 1fM）和检测速度（<15s）。这种出人意料的简单策略可能为传感器设计开辟机会，使其能够广泛实现对痕量生物标志物的即时检测，并直接在生理状态下实时探测生物分子功能。
