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A novel SERS substrate based on silver nanoparticles-capsulated single porous glass microsphere

A novel surface-enhanced Raman scattering (SERS) substrate based on silver nanoparticles-capsulated porous glass microsphere (PGM) has been investigated. Ag+ ions were introduced into PGM interior as precursors, during which compressed CO2 gas with 150 psi pressure was employed to increase Ag+ loading capacity. After that Ag+ ions were in situ reduced to form Ag nanoparticles. The synthesized sample was characterized by scanning electron microscopy and energy dispersive spectrometer. As a result Ag nanoparticles encapsulation has been identified. SERS performance was evaluated by Rhodamine 6G and benzoic acid solutions, and obvious Raman enhancement was obtained. The enhancement effect was revealed to be superior to similar substrates, Ag-coated porous and nonporous microsphere prepared via silver mirror reaction. Response of Ag-capsulated PGM and large Ag-coated NPGM to Hg2+ were demonstrated. With the advantages of Raman enhancement, small size, fabrication convenience and operation flexibility, Ag-capsulated PGM is believed to have considerable application prospect in chemical and biological micro-sensor area.