Using Gelatin as Protecting Agent and Organic Template to Synthesize Noble Metal Nanoparticles and Metal Nanoparticles@Mesoporous Silica for SERS and CO Oxidation Applications

With excellent control of their synthetic compositions and condition, noble metal nanoparticles@mesoporous silicas of large surface area (= 300 m2g-1), large pore size ( > 5.0 nm), and high noble metal nanoparticle content (= 10 wt.%) have been conveniently prepared using natural polymer gelatin with many amide (-CO-NH2) groups as an organic template of mesoporous silica and a protecting agent for stabilizing Au nanoparticles. This synthetic method is extensive and can be used to prepare Au, Ag, and Ag-Au alloy nanoparticles@mesoporous silicas. Because the metal nanoparticles are accessible to the environment, noble-metal nanoparticles@mesoporous silicas can be used in SERS applications and act as superior catalysts in CO oxidation at high temperatures. In addition, bare Au nanoparticles anchored on a silica matrix can have direct contact with S. aureus cells to enhance the Raman spectrum intensity of S. aureus cells absorbed onto a Au nanoparticles@mesoporous silica.