Transistor sensing in salt solutions Molecular binding to receptors on the surface of field-effect transistors (FETs) can be sensed through changes in transconductance. However, the saline solutions typically used with biomolecules create an electrical double layer that masks any events that occur within about 1 nanometer from the surface. Nakatsuka et al. overcame this limitation by using binding to large, negatively charged DNA stem loop structures that, upon ligand binding, cause conformational changes that can be sensed with an FET, even in solutions with high ionic strength. The authors demonstrate the sensing of charged molecules such as dopamine in artificial cerebrospinal fluid as well as neutral molecules such as glucose and zwitterion molecules like sphingosine-1-phosphate. Science, this issue p. 319 Large conformational changes induced in charged DNA stem-loop receptors can be sensed in high–ionic strength solutions. Detection of analytes by means of field-effect transistors bearing ligand-specific receptors is fundamentally limited by the shielding created by the electrical double layer (the “Debye length” limitation). We detected small molecules under physiological high–ionic strength conditions by modifying printed ultrathin metal-oxide field-effect transistor arrays with deoxyribonucleotide aptamers selected to bind their targets adaptively. Target-induced conformational changes of negatively charged aptamer phosphodiester backbones in close proximity to semiconductor channels gated conductance in physiological buffers, resulting in highly sensitive detection. Sensing of charged and electroneutral targets (serotonin, dopamine, glucose, and sphingosine-1-phosphate) was enabled by specifically isolated aptameric stem-loop receptors.

中文翻译：

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适体场效应晶体管克服了小分子传感的德拜长度限制

盐溶液中的晶体管感应 与场效应晶体管 (FET) 表面受体的分子结合可以通过跨导的变化来感应。然而，通常与生物分子一起使用的盐水溶液会产生一个双电层，可以掩盖距离表面约 1 纳米范围内发生的任何事件。中冢等人。通过使用与大的带负电荷的 DNA 茎环结构的结合来克服这一限制，这些结构在配体结合时会引起构象变化，即使在具有高离子强度的溶液中也可以用 FET 检测到。作者展示了人工脑脊液中带电分子（如多巴胺）以及中性分子（如葡萄糖）和两性离子分子（如 1-磷酸鞘氨醇）的感应。科学，这个问题 p。319 在高离子强度溶液中可以检测到带电 DNA 茎环受体引起的巨大构象变化。通过带有配体特异性受体的场效应晶体管检测分析物从根本上受到双电层产生的屏蔽（“德拜长度”限制）的限制。我们通过用脱氧核糖核苷酸适体修饰印刷的超薄金属氧化物场效应晶体管阵列来检测生理高离子强度条件下的小分子。靠近半导体通道的带负电荷的适体磷酸二酯骨架的目标诱导的构象变化在生理缓冲液中门控电导，导致高度灵敏的检测。检测带电和电中性目标（血清素、多巴胺、