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 m ²g^-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.