Different samples of sodium alginate grafted by polyacrylonitrile copolymer were synthesized via the grafting process through a free radical polymerization mechanism. Graft structures were characterized and confirmed using Fourier Transform Infrared (FT-IR) spectroscopy and X-Ray diffraction (XRD). Thermogravimetric analysis (TGA) showed that the graft copolymers acquired higher thermal stability compared to native alginate. Moreover, its solubility in several solvents was examined as compared to that of native alginate. The main outcome of this paper was that a grafted copolymer with hydrophobic enrichment (Wt% = 150 %) of polyacrylonitrile as a core was sufficient to form stabilize colloidal system within nanoparticles have Z-average diameter equal 55 nm and sodium alginate as a shell. The SA-g-PAN graft copolymer showed a higher degree of swellability in the basic medium than in acidic medium. The consequence of that was the SA-g-PAN graft copolymer exhibited pH-responsive properties. Moreover, the formed nanoparticles were loaded by a hydrophobic model and proofed by a transmission electron microscope (TEM).