Iron-mediated assembly of lactoferrin-alginate composites for iron encapsulation and structural stabilization

Ternary composite systems formed by lactoferrin (LF), sodium alginate (Alg), and Fe(II) were designed to investigate their potential as an iron delivery platform with enhanced protein stability. The ternary LF-Alg-Fe (LAF) composites demonstrated distinct structures depending on the LF to Alg ratio and the Fe(II) concentrations. At an LF to Alg ratio of 8:2 and final Fe concentrations between 20 and 30 mM, the system formed complexes stabilized by electrostatic interactions. Alg-rich formulations formed hydrogels stabilized by Alg-Fe(II) egg-box cross-linking. Rheological analysis and swelling behavior indicated a higher mechanical strength in LF-rich complexes and stronger network integrity in Alg-rich hydrogels. Thermal studies indicated that these ternary systems improved LF stability, evidenced by preserved secondary structure after heating using circular dichroism (CD), and an increased denaturation temperature. In addition, in LF-rich formulations the Fe(II) release in aqueous solution was ~50% while in Alg-rich formulations it was much lower (< 10%).