Enhanced Nanoparticle Sensing in a Highly Viscous Nanopore

Area of Science:

• Nanofluidics
• Nanoparticle characterization
• Biophysics

Background:

• Slowing translocation dynamics is essential for accurate nanopore sensing of nanoscale objects.
• Existing methods often struggle with efficient capture and signal resolution.
• Controlling fluid properties within nanofluidic channels presents a significant challenge.

Purpose of the Study:

• To investigate nanoparticle motion-mediated local viscosity enhancement in water-organic mixtures within a nanofluidic channel.
• To explore the impact of transmembrane voltage on translocation speed and capture efficiency.
• To demonstrate a novel mechanism for achieving slow translocation speeds and improving signal-to-noise ratio.

Main Methods:

• Utilized a nanofluidic channel with water-organic mixtures.
• Employed transmembrane voltage control to manipulate nanoparticle motion.
• Investigated local viscosity changes induced by nanoparticle movement at high shear rates (>10^3 s^-1).
• Tested the mechanism with various organic molecules like glycerol, xanthan gum, and polyethylene glycol.

Main Results:

• Nanoparticle motion enhances local viscosity, enabling slower translocation speeds.
• Higher electrophoretic voltage initially increases detection rates in viscous solvents.
• At high shear rates, induced dilatant viscosity leads to counterintuitive slower translocation under higher voltage.
• Achieved enhanced capture efficiency and improved signal-to-noise ratio.

Conclusions:

• Nanoparticle motion-mediated viscosity enhancement offers a simple and effective method for translocation slowdown in nanopore sensing.
• This approach significantly improves detection throughput and signal quality for analyzing nanoscale objects.
• Findings are applicable to resistive pulse analyses of viruses, proteins, and other nanoscale particles.