BACKGROUND:  Simple emulsions are dispersions of droplets of one liquid phase in another immiscible liquid phase. The most common are oil-in-water (O/W) or water-in-oil (W/O) emulsions that typically have microscale diameters. Double emulsions are more complex emulsions that consist of droplets within droplets, such as water-in-oil-in-water (W/O/W). The two primary means of creating double emulsions are structured microfluidic methods and sequential emulsification. Microfluidic methods are capable of producing highly uniform W/O/W emulsions, but it is a low-throughput process. A W/O/W double emulsion created by sequential emulsification must be size-fractionated to achieve uniform monodisperse droplets, but fractionation is also a low-throughput process. Most double emulsions rely on two surfactants for stability, not a single surfactant that can stabilize both inner and outer droplets. None of the existing double emulsification methods have so far been successful in creating nanoscale double emulsions in which both the inner and outer droplets are both sub-100 nm using a single type of surfactant.

INNOVATION:  The invention utilizes novel amphiphilic diblock copolypeptides that function as surfactants to stabilize stable double emulsions that can be formed using a variety of mixing methods using a single interfacial agent that is not biased against complex droplet topologies. An additional innovation is that both the inner aqueous droplets and outer oil droplets can be formed with diameters as small as tens of nanometers.

POTENTIAL APPLICATIONS:  Co-polypeptide stabilized double emulsions provide both microscale and nanoscale drug delivery vehicles that can package both water-soluble and oil-soluble drugs or other cargo. Dual delivery of hydrophobic and hydrophilic cargo will have applications in pharmaceuticals, cosmetics, and personal care products.

ADVANTAGES

• Control of inner and outer droplet sizes from the microscale down to tens of nanometers
• Tunable block lengths and compositions of the diblock copolypeptides to alter emulsion properties
• The inner liquid droplet (e.g. water) can contain water soluble cargo: DNA, RNA, oligonucleotides, peptides, proteins, salts, viruses, vitamins, serums, molecular motors, drug molecules, cells, vesicles, nanoparticles, fullerenes, carbon nanotubes, sugars, quantum dots, metal nanoparticles, magnetic nanoparticles, fluorescent dyes, etc.
• The outer droplet (e.g. oil) can contain hydrophobic cargo: fats, lipids, waxes, oils, fragrances, cholesterol, steroids, drug molecules, polymers, polypeptides, micelles, quantum dots, nanoparticles, carbon nanotubes, fullerenes, etc.
• A variety of oils can be used, including oils that are biologically compatible.

DEVELOPMENT-TO-DATE:  The process has been experimentally verified.

Reference: UCLA Case No. 2007-574