安定な多糖類in situ修飾金ナノ粒子のジスルフィド架橋アルギン酸を用いた還元的合成

Gold nanoparticles (AuNPs) are promising for biomedical applications, but their synthesis often requires toxic reagents. "Green" methods utilizing biopolymers offer a sustainable alternative. This study presents a novel synthesis of stable gold nanoparticles using a disulfide-crosslinked derivative of alginic acid (AA-S-S-AA) as both a reducing agent and stabilizer. The S-S-cross-linked alginate was synthesized with a degree of substitution of ~4.2% and reacted with HAuCl₄ in water at room temperature for just 10 min to give stable and polysaccharide in situ modified gold nanoparticles (AA-AuNPs). The resulting AA-AuNPs were characterized by a surface plasmon resonance peak at 539 nm and exhibited good colloidal stability over 14 days. Electron microscopy revealed spherical nanoparticles with a bimodal size distribution (10 nm and 75-100 nm) and a visible polysaccharide shell (5-9 nm), confirming effective stabilization. X-ray photoelectron spectroscopy confirmed the presence of metallic gold (Au⁰) and Au¹⁺. NMR analysis indicated the oxidation of disulfide groups to sulfonic acid during synthesis. The nanoparticles demonstrated a high negative zeta-potential of -53.9 mV, attributable to the polyanionic alginate corona, ensuring strong electrostatic stabilization. This work establishes sulfur-modified alginic acid as an efficient platform for the rapid synthesis of stable, hybrid nanoparticles for potential use in catalysis and biomedicine.