纳米孔道单分子电化学测量仪器的稳定性研究

纳米孔道分析技术是一种基于电化学空间限域效应的单分子检测技术。测量纳米孔道产生的单分子皮安级微弱电流信号对电化学测量仪器的电流分辨、时间分辨和抗噪音能力提出了挑战。Cube纳米孔道电化学测量仪器通过设计频率补偿电路、前置电流放大器测量系统和基于现场可编程逻辑门阵列(FPGA)的高速数字处理电路，实现了便携式超灵敏电化学测量仪器对微弱电流信号的高时间分辨、高电流分辨，以及低噪音的放大、采集和快速处理。稳定性是仪器能够应用于实际单分子测量分析的重要衡量指标之一。该文通过高阻值电阻对该仪器进行稳定性测试，在截止滤波频率为5、10、100 kHz条件下，Cube纳米孔道仪器获取的电流基线的噪音均方根(RMS)值分别比商品化仪器减小了80.0%、87.5%、48.2%，证明Cube纳米孔道仪器抑制噪音能力更强，电流分辨能力更好，仪器测量稳定性更佳。进一步通过统计比较施加电压值的实际值和标准偏差，结果显示该仪器施加电压误差小，其仪器施加电压标准偏差仅为施加电压变化量(10 mV)的0.14%。同时，通过Aerolysin纳米孔道检测Poly(dA)4的实验，对比Cube仪器和商品化仪器在不同施加电压下获取的单分子信号残余电流程度，得到两者误差均小于0.01，结果具有可重复性。因此，Cube纳米孔道仪器具有稳定性好、灵敏度高、便携性强的特点，可应用于纳米孔道单分子分析。

Scientific PapersStability Analysis of Nanopore Electrochemical Instrument for Single-molecule Measurement

Nanopore electrochemistry achieves the single-molecule measurement based on the electrochemically confined effect.The detection of picoampere-level current signals with milli-second duration makes a great challenge for the electrochemical instruments,which requires not only low noise and high current resolution,but also high bandwidth for capturing the rapid signals.A portable Cube ultrasensitive nanopore instrument consisting of a frequency compensation circuit,a pre-amplifier measurement system and a field programmable gate array (FPGA) based high-speed digital processing circuit has achieved the ultra sensitive electrochemical measurement with high temporal resolution,high current resolution and rapid acquisition of weak current signals.In this study,the stability of this instrument was tested by utilizing a high resistance resistor.Compared with the commercial instrument,the noise root mean square(RMS) values of the current baseline obtained with the Cube ultrasensitive nanopore instrument were reduced by 80.0%,87.5% and 48.2% under the cut-off frequencies of 5,10 and 100 kHz,respectively.Therefore,the Cube ultrasensitive nanopore instrument has a strong ability to suppress noise,offering a better current resolution.Results showed that the deviation of the applied voltage of the instrument was only 0.14% of the applied voltage change(10 mV),verifying a negligible error for the applied voltage of this Cube instrument.An Aerolysin nanopore detection of Poly(dA)4 under different applied voltages demonstrated that the error of residual current blockage was less than 0.01 when both the Cube and commercial instrument were used.Therefore,the Cube ultrasensitive nanopore instrument was suitable for the single molecule detection with high stability,high sensitivity and strong portability.