title: Photochemical synthesis of biopolymer coated Aucore-Agshell type bimetallic nanoparticles.
abstract: Spherical Au nanoparticles have been prepared in the presence of a biopolymer, sodium alginate using UV-photoactivation technique. The particles are sodium alginate coated and are extremely stable. These Au nanoparticles have been used as seed for the synthesis of Aucore-Agshell type bimetallic nanoparticles. Sodium alginate is a carbohydrate-based biopolymer. In this synthesis it acts both as a reducing agent and a stabilizer for the evolved particles. Therefore, no extra capping agent is required from outside to make the generated particle stable. By varying the seed to silver ion ratios and using photoactivation technique Aucore-Agshell type bimetallic nanoparticles with various sizes and compositions have been synthesized. The method is very simple and reproducible and does not need any manipulative skill. Characterizations of these bimetallic nanoparticles have been done from their UV-visible spectroscopy, TEM/EDX, and AFM results. UV-visible extinction spectra reveal that the seed particles have an absorption maxima approximately 527 nm, attributed to the surface plasmon of the pure gold nanoparticles. From the TEM images the particle size of the gold seed particles was calculated to be 8.6 nm. The growth of bimetallic nanoparticles with time has been monitored. The finally evolved bimetallic Aucore-Agshell nanoparticles have a size in the range between approximately 10-14 nm. The particles are very stable and may have the potential for biological and catalytic applications.
authors.affiliation: Department of Civil Engineering, Indian Institute of Technology, Kharagpur 721302, India.
authors.forename: Anjali
authors.initials: A
authors.lastname: Pal
authors.forename: Kunio
authors.initials: K
authors.lastname: Esumi
mesh_terms: D000464:Alginates / Q000737:chemistry* / Q000528:radiation effects; D001704:Biopolymers / Q000737:chemistry* / Q000528:radiation effects; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003460:Crystallization / Q000379:methods*; D020723:Glucuronic Acid / Q000737:chemistry / Q000528:radiation effects; D006046:Gold / Q000737:chemistry* / Q000528:radiation effects; D006603:Hexuronic Acids / Q000737:chemistry / Q000528:radiation effects; D008027:Light; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008670:Metals / Q000737:chemistry / Q000528:radiation effects; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D010777:Photochemistry / Q000379:methods; D045663:Quantum Dots; D012834:Silver / Q000737:chemistry* / Q000528:radiation effects; D013499:Surface Properties
chemical_list: D000464:Alginates; D001704:Biopolymers; D020099:Coated Materials, Biocompatible; D006603:Hexuronic Acids; D046911:Macromolecular Substances; D008670:Metals; D012834:Silver; D006046:Gold; D020723:Glucuronic Acid