Confirming Silent Translocation through Nanopores with Simultaneous Single-Molecule Fluorescence and Single-Channel...

Area of Science:

• Nanopore Science and Technology
• Single-Molecule Biophysics
• Molecular Transport Phenomena

Background:

• Current understanding of nanopore transport relies heavily on electrical measurements of ionic current.
• Nanopore characterization typically involves detecting electrical signatures associated with material passage.
• The phenomenon of transport without an electrical signature, termed 'silent translocation,' remains largely unexplored.

Purpose of the Study:

• To investigate and characterize silent translocation through a nanopore.
• To demonstrate the occurrence of silent translocation using a specific fluorescent dye.
• To explore the factors influencing silent translocation events and quantify transport parameters.

Main Methods:

• Utilized a derivative of Cyanine 5 (sCy5a) for translocation studies.
• Employed simultaneous single-molecule fluorescence and single-channel electrical recordings.
• Formed bilayers over a closed microcavity to facilitate nanopore measurements.

Main Results:

• Confirmed the occurrence of infrequent silent translocations of sCy5a through the alpha-hemolysin (αHL) nanopore.
• Observed silent translocation events as a function of time, dye concentration, and nanopore population.
• Quantified translocation rates, effective energy barriers, and effective dye charge without electrical signatures.

Conclusions:

• Silent translocation is a viable phenomenon for molecular passage through nanopores.
• Ancillary measurement techniques, such as fluorescence, are essential for detecting silent translocations.
• This study provides a foundation for exploring previously hidden transport mechanisms in nanopores.