Synthesis of MBA-Encoded Silver/Silica Core-Shell Nanoparticles as Novel SERS Tags for Biosensing Gibberellin A3 Based on Au@Fe3O4 as Substrate

A surface-enhanced Raman scattering (SERS) tag is proposed for high-sensitivity detection of gibberellin A3(GA3). Silver nanoparticles (AgNPs) were synthesized using citrate reduction. 4-Mercaptobenzoic acid (MBA) was used for the Raman-labeled molecules, which were coupled to the surface of the AgNPs using sulfydryls. MBA was coated with silica using the Stöber method to prevent leakage. GA3antibodies were attached via the active functional groups N-Hydroxysuccinimide (NHS) and N-Ethyl-N’-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) to construct a novel[email protected]2SERS tags. The captured SERS substrates were fabricated through Fe3O4nanoparticles and gold nanoparticles (AuNPs) using chemical methods. These nanoparticles were characterized using ultraviolet-visible spectroscopy (UV–Vis), dynamic light scattering, Raman spectroscopy, transmission electron microscope (TEM), and X-ray diffraction (XRD). This[email protected]2SERS tags has a strong SERS signal based on characterizations via Raman spectroscopy. Based on antigen-antibody reaction, the[email protected]3O4nanoparticles can capture the GA3and[email protected]2SERS tags. Due to the increasing number of captured nanoprobes, the SERS signal from MBA was greatly enhanced, which favored the sensitive detection of GA3. The linear equation for the SERS signal was y = −13635x + 202211 (R2= 0.9867), and the limit of detection (LOD) was 10−10M. The proposed SERS tags are also applicable for the detection of other food risk factors.Keywords:surface-enhanced Raman scattering;[email protected]2core-shell nanoparticles;[email protected]3O4nanoparticle;gibberellin