Key Laboratory for Advanced Materials & School of Chemistry and Molecular Engineering , East China University of Science and Technology , Shanghai 200237 , P. R. China.
School of Pharmacy , East China University of Science and Technology , Shanghai 200237 , P. R. China.
ACS Sens. 2018 Apr 27;3(4):779-783. doi: 10.1021/acssensors.8b00021. Epub 2018 Apr 17.
Selectivity and sensitivity are two key parameters utilized to describe the performance of a sensor. In order to investigate selectivity and sensitivity of the aerolysin nanosensor, we manipulated its surface charge at different locations via single site-directed mutagenesis. To study the selectivity, we replaced the positively charged R220 at the entrance of the pore with negatively charged glutamic acid, resulting in barely no current blockages for sensing negatively charged oligonucleotides. For the sensitivity, we substituted the positively charged lumen-exposed amino acid K238 located at trans-ward third of the β-barrel stem with glutamic acid. This leads to a surprisingly longer duration time at +140 mV, which is about 20 times slower in translocation speed for Poly(dA) compared to that of wild-type aerolysin, indicating the stronger pore-analyte interactions and enhanced sensitivity. Therefore, it is both feasible and understandable to rationally design confined biological nanosensors for single molecule detection with high selectivity and sensitivity.
选择性和灵敏度是用于描述传感器性能的两个关键参数。为了研究 aerolysin 纳米传感器的选择性和灵敏度，我们通过单点定向诱变来操纵其表面在不同位置的电荷。为了研究选择性，我们将孔入口处带正电荷的 R220 替换为带负电荷的谷氨酸，从而几乎不会阻断对带负电荷的寡核苷酸的检测。对于灵敏度，我们将位于β桶茎跨向第三位置的带正电荷的腔暴露氨基酸 K238 替换为谷氨酸。这导致在 +140 mV 时的持续时间惊人地延长，与野生型 aerolysin 相比，多聚（dA）的迁移速度慢了约 20 倍，表明孔-分析物相互作用更强，灵敏度更高。因此，对于具有高选择性和灵敏度的单分子检测，合理设计受限生物纳米传感器是可行且可理解的。
