Force Measurements on Oil and Liposomes With the Nanotracker 2 Optical Tweezers System

^{KEYWORDS: Optical Tweezers; NanoTracker; Liposomes; Oils; Emulsions; Colloids; Optical Trap; Force Measurements; Nanomanipulation; Life Science}

The versatile NanoTracker 2 system is designed for the optical trapping of dielectric particles and optically refractive objects. Sizes range from sub-micrometer polystyrene and silica beads to living cells with diameters greater than 10 microns. After automated calibration of the trap-particle system, the precise and reliable measurement of piconewton forces is possible. Applications include single-molecule mechanics and the micro-rheology of fluid and soft matter materials. In different fields of research, interest in the investigation of lipid and oil-water emulsion systems has grown. Micrometer sized, lipid enclosed cargo droplets play decisive roles in intracellular transport and metabolism processes, and the properties of oil/water or liposome emulsions are of great interest for oil production and cosmetics and medical drug delivery applications.

In this application note, the handling of and force measurements with oil and lipid droplets in aqueous solution using the NanoTracker 2 are introduced, further extending the range of possible applications.

Readers can expect to learn about:

• Viscous drag force experiments on multilamellar lipid vesicles and oil/water emulsions;
• Characterization of surface interaction forces and adhesion between individual droplets; and
  
• The versatility of the NanoTracker Optical Tweezers system and possible application in, e.g., droplet fusion experiments, the investigation of viscous properties,  intracellular transport and trafficking and the influence of surfactants or polymer additives on emulsion properties.