Polyelectrolyte Microcapsules Enhance the Stability of β-Galactosidase Under Simulated Gastrointestinal Conditions

Oral enzyme replacement therapy for lactase deficiency is limited by the rapid degradation of free β-galactosidase in the gastrointestinal tract. To overcome this, β-galactosidase was encapsulated into polyelectrolyte microcapsules (PMCs) via layer-by-layer assembly using MnCO3 sacrificial templates, with CaCO3-based PMCs as a reference. MnCO3-PMCs achieved 99.4% encapsulation efficiency and retained 85.8% of initial activity, significantly outperforming CaCO3-PMCs (86.0% and 29.7%). Under simulated gastric conditions (pH 2.0, pepsin), the free enzyme and CaCO3-PMCs were completely inactivated, whereas MnCO3-PMCs preserved ~86% activity. In simulated intestinal fluid, MnCO3-PMCs exhibited a 4.3-fold activity increase within the first hour and maintained a 2.5-fold enhancement after 70 h, while the free enzyme progressively inactivated. Furthermore, MnCO3-PMCs demonstrated superior storage stability, retaining 64% of initial activity after 90 days at 4 °C, compared with 25% for CaCO3-PMCs. Although immobilization increased the Michaelis constant, the shift was smaller for MnCO3-PMCs (8.9-fold) than for CaCO3-PMCs (15.2-fold). In conclusion, MnCO3-templated PMCs effectively protect β-galactosidase from gastrointestinal degradation, sustain prolonged catalytic activity, and offer excellent storage stability, highlighting their strong potential for improving oral enzyme replacement therapy in lactose intolerance.