Encapsulation takes many forms with the main objectives of controlled release or delivery of the agent(s) and protection of the agent(s) from degradation prior to the intended delivery. Additionally encapsulations may be used to incorporate agents that may be difficult or impossible to deliver without irritating levels of stabilizers such as emulsifiers or surfactants.
Several references describe encapsulation via coacervation. For example, U.S. Pat. No. 5,540,927 discloses a process for microencapsulation of materials by means of complex coacervation employing gelatin and polyaspartic acid. Polyaspartic acid or a salt thereof is employed to provide a counter ion to the gelatin which, when induced to precipitate from solution by cooling and/or pH change forms a wall around the material. The reference addresses leakage and failure to encapsulate a target solution. WO 2013113830 A1, WO 2012120043A3, and U.S.2014/0045949 describe complex methods for preparing capsules including a liquid core, a stiffened intermediate shell, and an outer gel shell, including a step of forming a multi-component drop, a gelling step, and a stiffening step via an interaction of a coacervate precursor system introduced at the interface of the formation of the droplet to be encapsulated.
Previous techniques, however, suffered some disadvantages such as phase mixing between the encapsulated material and non-encapsulated material, exposure of the encapsulated material to environmental conditions that allowed degradation of the encapsulated material and lengthy steps in the process. In addition, most of the prior techniques only briefly describe topical formulations.
USPTO Backgrounds
USPTO Backgrounds