Lead (II) is one of the commonly encountered toxic substances in the environment and poses significant negative health effects when they are present in drinking water as less as parts per million concentrations. Long-term drinking of lead-contaminated water may result in kidney problems and high blood pressure for adults, as well as the physical and mental development delays in infants and children. Therefore, developing a new and portable analytical technology for detection of lead ions in aqueous media is important for environmental monitoring. In this work, a label-free method for the detection of Pb(II) ions is developed by monitoring the translocation of a Cys4 zinc-finger motif in a nanopore in the absence and presence of lead ions. In the absence of Pb(II), the Cys4 zinc-finger is unfolded, and hence could translocate through an α-hemolysin protein pore, thus producing current modulations. In the presence of Pb(II), the Cys4 zinc-finger folds, which is too large to pass through the nano-cavity, leading to the disappearance of the current blockage events. The method is highly sensitive: trace amount of Pb(II) ions could be detected in minutes. Furthermore, the sensor is selective: other metal ions including Zn(II) with concentrations of up to three orders of magnitude greater than that of Pb(II) would not interfere with Pb(II) detection.

Nanopore-based biosensor for lead ion detection using a Cys4 zinc-finger motif

256th National Meeting (2018)

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