Algal polysaccharide capsule-templated growth of magnetic nanoparticles

Polysaccharidic alginate biopolymers have been used as templates for the controlled growth of magnetic nanoparticles. Ni2+ and Co2+ can used to form alginate gels as spherical capsules. UV-visible absorption spectroscopy allowed the investigation of the environment of the metal ions within the biopolymer network. Reduction under. owing H-2/N-2 led to the formation of Co and Ni nanoparticles as well as CoNi nanoalloys. Even at 350 degrees C, the organic matrix was partially preserved. XRD, TEM and XPS analyses were used to characterize particle structure, size and morphology. SQUID measurements indicated that all particles were ferromagnetic at 2 K. This work suggests that alginate provides a well-defined, chemically and thermally stable environment for the formation of nanoparticles, leading to magnetic nanocomposites.