Stochastic Sensing of Organotin Compounds with Alpha-Hemolysin Nanopore

Organotin compounds (OTCs) are pollutants that affect the reproduction of some marine organisms and can cause autoimmune diseases in humans. Most of the techniques used for detection and monitoring of OTCs in the environment have limitations due to several stages of sample pre-processing. Here, we demonstrated the use of the α-hemolysin (αHL) nanopore as an alternative platform for the detection of the cyhexatin and diphenyltin dichloride (DPhT) in aqueous systems. The detection process is based on the analysis of the residence times of each OTCs within the unitary nanopore, as well as, on the amplitudes of the blockages in the ionic current flowing through it. Cyhexatin and DPhT induced two and three patterns in the amplitude of the blockages in the ionic current, respectively. Residence time value of the cyhexatin inside the nanopore was higher than the value presented by the DPhT. Molecular docking was used to evaluate the interactions between OTCs and nanopore constriction, mainly identifying cation-π and hydrogen interactions. Classical atomistic molecular dynamic simulations confirm moderate aggregative behavior of these OTCs in solution in cationic form, especially for cyhexatin species. The nanopore detects OTCs at nanomolar level and it is possible to use this nanopore to monitor OTCs in aqueous systems.

Keywords:
alpha-hemolysin; organotin compounds; stochastic sensing; cyhexatin; diphenyltin dichloride