Spatially Extended DNA Phase Separation in Viscosity-Stratified Miscible Interfaces: Application in Microliter...

Area of Science:

• Interfacial hydrodynamics
• Molecular self-assembly
• Materials science
• Biophysics

Background:

• Interfacial hydrodynamics and molecular self-assembly are crucial for developing advanced materials and sensors.
• Viscosity gradients in flowing fluids create complex hydrodynamic events, impacting areas like microfluidics and tissue engineering.
• The behavior of liquid-liquid phase separation (LLPS)-driven membraneless biocondensates in these gradient zones remains largely unexplored.

Purpose of the Study:

• To investigate the formation of DNA-spermine condensates within the hydrodynamically unstable region of a microfluidic device under continuous flow.
• To explore the influence of varying solution viscosity on LLPS-mediated condensate formation.
• To assess the potential of this phenomenon for developing novel viscometric techniques.

Main Methods:

• Utilized a microfluidic device to create a continuous flow with a controlled viscosity gradient (Δη) using polyethylene glycol as a crowding agent.
• Observed and analyzed the formation and characteristics of DNA-spermine condensates within the viscous-stratification region.
• Applied the developed approach to microliter-scale samples, including blood serum, for viscometric analysis.

Main Results:

• Demonstrated LLPS-mediated DNA-spermine condensate formation in the hydrodynamically unstable viscous-stratification zone.
• Observed a significant increase (∼2.3-fold) in the width of the condensate clustering zone with increasing interfacial viscosity contrast (Δη).
• Noted distinct changes in condensate coarsening and size distribution skewness at interfaces with contrasting viscosities.

Conclusions:

• The study successfully demonstrates the formation of DNA-spermine condensates in a microfluidic viscosity gradient, driven by LLPS.
• The findings highlight the impact of interfacial hydrodynamics on molecular self-assembly and condensate behavior.
• The research presents a novel microliter-scale viscometric technique with potential applications in pathological analysis, such as gamma-globulin detection in blood serum.