Emulsions, and particles prepared from them, play a central role in pharmaceuticals, food, and consumer products. Recently, the ability to create multiple emulsions (i.e. complex emulsions that contain droplets inside larger droplets) has led to significant advances in our ability to create multi-compartment colloids. However, methods to make well-controlled emulsions have been primarily limited to sizes larger than 10 µm. As such, translating the preparation of multiple emulsions to the nanoscale would open new opportunities for the synthesis of multi-compartment nanoparticles with sophisticated capabilities for controlled encapsulation and release.
To date, the only reports of nanoscale multiple emulsions have been water-in-oil-in-water (W/O/W) emulsions, significantly limiting the classes of materials that can be prepared from them. Here, we report a technique to form oil-in-water-in-oil (O/W/O) multiple emulsions on the nanoscale, and use them to fabricate nanogel particles of poly(ethylene glycol) diacrylate (PEGDA) with encapsulated oil nanodroplets. To demonstrate the versatility of the method, we show how the composition of these particles can be systematically varied while still retaining a high degree of control over the particle synthesis. We then demonstrate encapsulation and release of a variety of small molecules and biomolecules to show how these particles can be adapted for a number of applications. This versatility and adaptability make nano-organohydrogels an appealing material platform for a wide array of applications, including drug delivery.