Tough and long-term storage cellulose nanocrystals polyelectrolyte microcapsules (CNCs-PEMCs) prepared by aqueous two-phase system and microfluidic technology for horseradish peroxidase encapsulation and release

Microcapsules have emerged as versatile microcarriers in the biomedical and biological fields. Herein, we successfully fabricated polyelectrolyte microcapsules (PEMCs) with favorable release and storage characteristics through an integrated approach utilizing an aqueous two-phase system (ATPS) with microfluidic techniques. The PEMCs were synthesized at the interface between the dispersed and continuous phases by layering oppositely charged polyelectrolytes: poly(diallyldimethylammonium chloride) (PDDA) and polystyrene sodium sulfate (PSS). To improve the robustness, storage potential, and biocompatibility of the microcapsules, cellulose nanocrystals (CNCs) were integrated into the microcapsule matrix. The resulting microcapsules, which encapsulated FITC-labeled dextran (FITC-Dex), displayed tunable release characteristics in different poly(ethylene glycol) and phosphate-buffered saline solutions, suggesting that CNCs-PEMCs could be controlled by osmotic pressure and pH. Additionally, horseradish peroxidase (HRP), a model enzyme, had preserved catalytic function within the PEMCs for over 24 h, demonstrating that the microcapsules do not significantly affect enzymatic activity. The formation of a cohesive shell by integrating of CNCs with polyelectrolytes under neutral conditions shows the potential of these CNCs-PEMCs for broader applications.