An adsorption-based model for pulse duration in resistive-pulse protein sensing

Area of Science:

• Nanotechnology
• Electrochemistry
• Biophysics

Background:

• Nanopore resistive-pulse sensing is an electrochemical technique for single-molecule detection.
• Gold nanotube sensors are used to count protein molecules by measuring ionic current changes.

Purpose of the Study:

• To develop a model explaining the long duration of current pulses generated by protein translocation through nanopores.
• To account for the observed pulse shape and duration variations with protein size.

Main Methods:

• Utilized nanopore resistive-pulse sensing with gold nanotube sensors.
• Applied a transmembrane potential and measured ionic current changes during protein translocation.
• Developed a model based on protein adsorption/desorption events within the nanotube.

Main Results:

• Protein translocation generates current pulses significantly longer than expected transport time.
• The model accurately predicts long pulse durations, triangular pulse shapes, and increased duration variability with protein size.
• Observed protein adsorption behavior consistent with other surface interaction studies.

Conclusions:

• Protein adsorption/desorption events are critical to understanding nanopore sensing dynamics.
• The model provides a framework for accurate single-molecule counting and characterization using nanopore sensors.
• Findings align with broader principles of protein-surface interactions.