Encapsulation of liquid bioactive ingredient formulations using coaxial multi-fluid nozzles and the vibrating jet technique

• Applicant: Professor Dr. Markus Thommes
• Subject Area: Mechanical Process Engineering
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 552808105

This project will elucidate the mechanisms of jet decay from multi-fluid nozzles using the vibrating jet technique, which is not understood so far. In particular, the interplay between material attributes, process conditions as well as product properties will be described mathematically. This fundamental research is independent from any application even if the encapsulation of pharmaceutical capsules will be used for purpose of discussion. Therefore, a lipid-based liquid bioactive core is enveloped by a hydrophilic polymer-based shell, which is considered as dosage form for oral administration to a patient. Tight specifications with respect to the weight uniformity and mechanical properties must be met in order to comply with actual legal requirements. Our hypothesis is that non-ionic hydrocolloid-based materials are suitable to encapsulate lipid-based bioactive ingredient solutions using the vibrating jet technique. The developed modeling approaches will define the shell composition and the encapsulation process conditions to achieve the desired capsule specifications. Initial work will be dedicated to the design of the capsule shell composition. The shell will consist of non-ionic hydrocolloids, plasticizers, and water. Empirical models will be derived to correlate the shell composition with the shell properties such as interfacial tension, viscosity and tensile strength. This project focuses in particular on the encapsulation process using vibrating coaxial multi-fluid nozzles, which will be rationally designed based on the material properties of the core and the shell solutions. Common empirical models for a single liquid phase, such as the Rayleigh-Decay, will be extended for that purpose. Finally, the findings regarding the critical material attributes and critical process parameters will be merged into a single and comprehensive model describing the encapsulation process. This will allow to predict critical quality attributes of the final capsules, like the weight uniformity, mechanical properties, and storage stability.

• DFG Programme: Research Grants