Improved Measurement of Proteins Using a Solid-State Nanopore Coupled with a Hydrogel

Area of Science:

• Nanotechnology
• Biophysics
• Analytical Chemistry

Background:

• Resistive pulse sensing with solid-state nanopores offers single-molecule sensitivity.
• Nanoparticles, including proteins, often transit nanopores too rapidly for accurate detection.
• This rapid transit leads to deviations in measured current amplitudes and detection rates from theoretical predictions.

Purpose of the Study:

• To enhance nanoparticle detection accuracy and resolution in nanopore measurements.
• To increase the residence time of nanoparticles within nanopores.
• To develop a label-free method for analyzing nanoparticle properties.

Main Methods:

• Utilizing a hydrogel placed on the distal side of a solid-state nanopore.
• Investigating the effect of the hydrogel on nanoparticle residence time and detection.
• Applying the hydrogel-backed nanopore technique to detect and differentiate proteins like IgG and bovine serum albumin.

Main Results:

• Hydrogel-backed nanopores significantly increased the detection frequency of IgG proteins by several orders of magnitude.
• Measured currents for IgG agreed well with theoretical models, indicating improved accuracy.
• The method enabled discrimination between IgG and bovine serum albumin in a mixed solution.
• Current amplitude distributions allowed for inference of IgG's approximate shape.

Conclusions:

• Hydrogel-backed nanopores are a simple, inexpensive, and label-free method to improve nanoparticle detection.
• This technique enhances resolution and enables quantitative analysis of nanoparticle properties.
• The approach is versatile and applicable to various nanoparticle targets, including proteins.