Microencapsulation

It is common to define Microencapsulation as the embedding of at least one ingredient (active agent) into at least one other (shell material). The active agent is usually not suitable to use it directly due to several reasons: low solubility, reactivity (to low or high), stability (low). On the other hand, it may be of advantage to optimize the properties of the active agents, e.g. by using controlled release. For all practical aspects a common classification into two basic methods can be made:

  • Matrixencapsulation
  • Core-Shell-Encapsulation
Releasecurves for matrixencapsulation and core-shell-encapsulation
Release for matrixencapsulation (bright red=small diameter, bright green=large diameter) and core-shell-encapsulation (dark red=thin shell, dark green=thick shell)
Schematic of Microspheres/Microcapsules
Schematic of microgranulates (left to right): Microcapsule with homogenous core, Microcapsule with cell supsension as core, Microsphere with homogenous mixture

BRACE GmbH offers solutions for all methods. For each active agent individual recipes and processes are applied. The BRACE-processes for microgranulation can be used to encapsulate a wide range of materials. These processes produce monomodal, ultraspherical microgranulates with a very low size distribution. The services offered by BRACE GmbH are recipe development for clients, contract manufacturing and microsphere units starting at the desktop unit Spherisator S and Spherisator M up to production units.

Matrixencapsulation

Matrixencapsulation is used if the active agent is distributed homogeneous in the shell material. A Microsphere is a spherical particle of a homogeneous mixture. BRACE GmbH develops for its customers recipes which enhance the application due to their ultraspherical form.

These Microspheres are able to release the encapsulated active agents over a defined time. Controlled release Microspheres are optimized by a suitable choice of the shell material and the chosen particle size. The choice of shell materials suitable for the application can be waxes, hydrocolloids or other organic or inorganic materials. Wax embedded active agents with defined controlled release curves and an enhanced stability of the embedded chemicals are produced for cosmetic or pharmaceutical applications.
In other fields of application like food industries the retention time of the agent (e.g. a flavor) needs to be enhanced. By the BRACE-processes it is even possible to produce homogeneous catalysts in a one step reaction so that the catalytic additives are distributed evenly in a carrier with extremely high BET surface.

Core-Shell-Encapsulation

If the release of the active agent should either be spontaneous or slowly over a very long time, the
Microspheres cannot fullfill the requirements of the application. For these cases a core-shell-encapsulation if preferred. A spherical particle with a solid shell is commonly denominated as Microcapsule. They are used in applications like chewing gum with an extraordinary taste or anti-allergic bedware which keeps its features over years and even after a hot wash. BRACE GmbH uses a special drip casting process for the production of Microcapsules which produces true core-shell Microcapsules in a single step.

The suitable range of shell materials is very broad, since most gelling systems can be used. In general the most commonly used shell materials are hydrocolloids like alginate, agar-agar, gelatin but also gum arabicum, latices, polymethacrylates, polyethersulfones, wax and many more. The core material needs to be liquid which makes hydrophilic (e.g. aqueous solutions) and also hydrophobic agents (e.g. oils) suitable for the process. For even finer release tuning, the Microcapsules can be processed after the production by coating, polymerisation or cross-linking to adjust the properties to the desired needs.

Applications

BRACE Microspheres and Microcapsules are used in many different applications in chemical, pharmaceutical, cosmetic and food industries. They are used for anti-allergic bedware (resistent to high temperatures, effective for up to two years), flavor encapsulation (chewing gum, cookies, ready meals, cigarettes), catalysts (air filter, petro-chemical applications), food (Champagne production), pharmaceuticals (painkiller, bone cement), cosmetics (skin care, shower gel, shampoo) and many more. If there is a solution, BRACE GmbH has it.