Reduced graphene oxide nanosheets decorated with core-shell of Fe3O4-Au nanoparticles for rapid SERS detection and hyperthermia treatment of bacteria

In this study, the core–shell of Fe3O4-Au nanoparticles (NPs) were prepared by seeding AuNPs onto Fe3O4 NPs modified with poly-ethylenimine (PEI). Later, Fe3O4-Au NPs were attached to cationic poly(dimethyldiallylammonium chloride) (PDDA)-modified graphene oxide (GO) nanosheets through in situ self-assembly behaviors, termed as Fe3O4-Au@RGO nanocomposites, for surface-enhanced Raman scattering (SERS) detection and hyperthermia treatment of bacteria. The resulting Fe3O4-Au@RGO nanocomposites were evaluated systematically by transmission electron microscope, zeta potential, X-ray diffraction, X-ray photoelectron spectroscopy, and vibrating sample magnetometer. It revealed that the core–shell structured Fe3O4-Au NPs were dispersed homogeneously on the surface of the GO nanosheets. Furthermore, the rapid SERS detection for small biomolecules and bacteria was conducted by Raman spectroscopy. The results showed that the greatest SERS intensity was fne tuned at the weight ratio of Fe3O4-Au/RGO nanosheets was 20/1, displaying the optimal interparticle gap of AuNPs to induce the huge hot-spots effect. The magnetic inductive heating capability of Fe3O4-Au@RGO nanocomposites was produced under high frequency magnetic field exposure and can kill high than 90% of the bacteria at 10 min. Hence, the newly developed Fe3O4-Au@RGO nanocomposites were demonstrated to be viable for SERS detection of biomolecules and microbes and potential applications for magnetically capturing and hyperthermia treatment of bacteria.