Fabrication of Ag/SiO2 nanocomposite via the Stӧber and chemical reduction approach for detecting sub-ppm tetracycline concentration

In this work, we report the synthesis of an Ag/SiO₂ nanocomposite (NC) via the Stӧber method coupled with chemical reduction for the sensitive detection of tetracycline (TC) antibiotic at sub-ppm levels. The Ag/SiO₂ NC consists of monodisperse SiO₂ nanospheres (NSs) (∼200 nm) decorated with Ag nanoparticles (NPs) of approximately 9.8 nm. Structural analysis confirms that the Ag NPs exhibit a highly pure face-centered cubic (FCC) phase with well-defined crystallinity. The Ag/SiO₂ NC demonstrates strong surface plasmon resonance (SPR) effects, with a characteristic peak at 400 nm, attributed to the interaction between the Ag NPs and the surface of SiO₂, thereby enhancing surface-enhanced Raman scattering (SERS) response. Leveraging these properties, we fabricated a SERS-based sensor using the Ag/SiO₂ NC for TC detection at room temperature (RT), achieving high sensitivity, selectivity, and rapid response within a concentration range of 0.01–1.0 ppm. These findings underscore the potential of Ag/SiO₂ NCs as advanced materials for chemical sensing applications, benefiting from enhanced SPR effects, superior light trapping, and increased Raman signal amplification, thereby significantly improving the detection limit.