The selection of cross-linking techniques is essential for the development of the alginate matrix. In this study, we investigated porous sodium alginate matrices (ALG1@in, ALG3@in, ALG5@in) synthesized by internal gelation and further functionalized with polyphosphate (PP) at concentrations of 5% and 15% (ALG3@inPP5, ALG3@inPP15). Extensive characterizations were conducted, employing scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS) for morphological and compositional analysis, Fourier transform infrared spectroscopy (FTIR-ATR) for structural elucidation, thermogravimetric analysis (TGA-DTG) for thermal stability, and porosimetry (ASAP) for surface area and pore size evaluation. Surface charge density (pH