Fast translocation of proteins through solid state nanopores

Area of Science:

• Biophysics
• Nanotechnology
• Materials Science

Background:

• Solid-state nanopores offer a promising platform for single-molecule analysis, including protein translocation.
• Theoretical models predict specific capture rates based on protein size and diffusion, but experimental data often deviates.
• Anomalous transport behavior in nanopore systems can hinder accurate characterization of biomolecules.

Purpose of the Study:

• To investigate the reasons behind the observed low event rates during protein translocation through solid-state nanopores.
• To systematically study the dependence of translocation event rates on protein size, diffusion constant, pore size, and concentration.
• To identify the primary factors contributing to the discrepancy between theoretical predictions and experimental observations.

Main Methods:

• Experimental measurements of protein translocation event rates across a range of protein sizes (6-660 kDa) and concentrations.
• Systematic variation of nanopore dimensions and protein diffusion constants.
• Analysis of event rate dependence on protein size and diffusion using a one-dimensional first-passage time-distribution model.

Main Results:

• Observed event rates are significantly lower than theoretically predicted, particularly for smaller, faster-diffusing proteins.
• The discrepancy between observed and predicted rates increases with decreasing protein size.
• A large protein (540 kDa) exhibited behavior closer to theoretical expectations compared to a small protein (37 kDa).

Conclusions:

• The anomalous transport behavior is primarily attributed to the limited temporal resolution and low signal-to-noise ratio of the detection system.
• Many proteins translocate faster than the current detection capabilities allow, leading to underestimation of event rates.
• Addressing these detection limitations is crucial for advancing protein characterization using solid-state nanopore technology.