Microfluidic-assisted T-junction internal gelation for phycocyanin encapsulation

Phycocyanin (PC), a high-value bioactive compound widely used in the food, cosmetic, and pharmaceutical industries, faces critical limitations due to its structural instability under external environments. To address these challenges, we present a microfluidic-assisted encapsulation strategy that offers significant advantages over conventional encapsulation techniques in terms of precision, uniformity, and structural control. This study introduces a surfactant-free internal gelation process within a T-junction microfluidic device, enabling in situ formation of calcium-alginate capsules via Ca-EDTA crosslinking. The method achieved highly uniform spherical capsules with an average diameter of 1.272 ± 0.025 mm, a high encapsulation efficiency of 89.19 ± 0.31 %, and a phycocyanin loading of 9.20 ± 0.19 % using an optimized formulation of 8 %(w/v) Ca-EDTA and 2 %(w/v) sodium alginate. Furthermore, chitosan coatings at varying concentrations were applied to modulate capsule stability and release behavior, showing enhanced protection in simulated gastric conditions and controlled release in intestinal environments. Compared to traditional bulk gelation or emulsion-based methods, this microfluidic platform offers superior control over capsule morphology and release kinetics without the need for surfactants or organic solvents. This work advances the field of algal biotechnology by providing a scalable, biocompatible, and tunable encapsulation system that significantly improves phycocyanin stability and delivery potential for functional food and drug delivery applications.