Fraunhofer researchers adapted the technique of spray drying, one used for producing instant coffee and powdered milk, for incorporating insoluble substances in core-shell particles and refining the encapsulation process of therapeutic drugs.
Encapsulation is a technique used in cosmetics and pharmaceuticals to protect the active ingredients of the drug from the influence of gastric acid and to control their release into the body. Thus, the medication is delivered gradually rather than all at once.
The process involves dissolving the active ingredient of the drug in a liquid medium and mixing it with the shell material. The solution is then piped whose orifice is surrounded by an annular channel injecting compressed air at high speed. The air pressure disperses the solution into an aerosol of fine droplets, which is then sprayed into a drying cylinder to obtain a fine powder of core-shell particles.
But the difficulty of mixing insoluble substances with the shell material limits their choice. To overcome this problem, the three-way nozzle was implemented for spraying by Fraunhofer researchers. “Its advantage is the ability to feed two substances separately to the nozzle. The shear forces mix the substances together at the orifice of the nozzle, creating an aerosol containing both materials,” explains Michael Walz, who developed and optimized this technique with his colleague Dr Achim Weber at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart.
“The technique modifies the encapsulation process and efficiency by permitting endless combinations of materials, enabling the controlled release of active ingredients, and developing solutions tailored to individual customer needs” says Weber.
This new process could benefit fertilizer manufacturers, food processing companies as well as the cosmetics and pharmaceutical industries.