Controlling the size and adhesion of DNA droplets using surface- enriched DNA molecules

Area of Science:

• Biophysics
• Materials Science
• Biochemistry

Background:

• Biomolecular liquid droplets organize cellular functions.
• These droplets are relevant for biosensing and biomaterials.
• Controlling droplet properties is key for applications.

Purpose of the Study:

• To investigate tuning interfacial properties of DNA nanostar droplets.
• To understand the role of DNA molecules as surfactants.
• To control droplet size and adhesion.

Main Methods:

• Utilized multi-armed DNA nanostar particles to form model biomolecular liquid droplets.
• Employed long DNA molecules with binding affinity as surfactants.
• Used fluorescent measurements to quantify interfacial density.
• Observed droplet size and adhesion to surfaces.

Main Results:

• Long DNA molecules preferentially enriched at droplet interfaces, acting as surfactants.
• Interfacial surfactant density reached approximately 20 per square micron, forming a sparse brush-like structure.
• Increased surfactant concentration reduced droplet size to sub-micron scale.
• DNA surfactants prevented droplet adhesion to both hydrophobic and hydrophilic surfaces.

Conclusions:

• Demonstrated effective control over biomolecular liquid droplet size and adhesive properties.
• The brush-like surfactant layer creates disjoining pressure, impeding coalescence and adhesion.
• Findings have implications for understanding biomolecular condensates and developing new biomaterials and biosensors.