Encapsulation of Lactoferrin in Calcium-Alginate Microparticles and Its Release Therefrom Under Neutral and Mild Acidic Conditions: Synthesis, Characterization and Mathematical Modeling

Bio-based polymeric stimuli-responsive materials have attracted increasing interest, especially in the pharmacological and nutraceutical fields. These materials mainly consist of macromolecules capable of conformational and chemical changes in response to external signals. One active molecule mostly used in bio-related areas is lactoferrin (Lf), which is attracting attention due to its beneficial effects (antimicrobial, anti-inflammatory, and anti-carcinogenic) on the human body. Since pH or temperature in the human body can promote Lf degradation, encapsulation in a suitable system is required. A valid solution is to encapsulate the Lf in a polysaccharidic matrix such as alginate (ALG) thanks to its biocompatibility and easy gelation with bivalent cations. This work aims to encapsulate iron-depleted Lf in alginate gel microspheres for stability improvement by ionic cross-linking with Ca²⁺ ions. The obtained particles were characterized in terms of structure, thermal stability, and morphology, and their swelling capability was determined. Release studies were carried out on the freeze-dried particles to investigate the effect of neutral pH 7 and acidic pH 5. At last, the optimization of the loaded system was completed by developing a mathematical model able to predict the swelling behavior of the carrier particle and the subsequent Lf kinetic release over time.