Continuous-flow separation of nanoparticles by electrostatic sieving at a micro-nanofluidic interface.

Area of Science:

• Microfluidics and Nanotechnology
• Separation Science
• Biophysics

Background:

• Continuous-flow separation of nanoscale particles is crucial for bioanalysis.
• Existing Lab-on-a-Chip devices have limitations in real-time, high-purity sorting.
• Nanoparticle (NP) and macromolecule separation requires precise control over fluid dynamics and surface interactions.

Purpose of the Study:

• To demonstrate continuous-flow separation of nanoparticles and proteins using electrostatic sieving.
• To develop a micro-nanofluidic device capable of selective nanoscale particle deflection.
• To assess the purity and applicability of the electrostatic sieving method for bioanalytical tasks.

Main Methods:

• Fabrication of a poly(dimethylsiloxane) microfluidic device with a 525 nm nanoslit.
• Exploitation of overlapping Debye layers within the nanoslit to create an electrostatic sieve.
• Continuous feeding of samples containing nanoparticles (15 and 39 nm) and proteins (6.8 nm) for separation.

Main Results:

• Achieved selective deflection and sorting of nanoparticles with up to 97% purity.
• Demonstrated the deflection of proteins, indicating applicability to biomolecules.
• Validated the continuous-flow operation with real-time parameter adaptability.

Conclusions:

• Electrostatic sieving at a micro-nanofluidic interface provides an effective method for continuous nanoparticle and macromolecule separation.
• The developed device offers a valuable addition to Lab-on-a-Chip technologies for real-time, high-purity sorting.
• This approach holds promise for advancing bioanalytical sample preparation and analysis.