Construction of optimized Au@Ag core-shell nanorods for ultralow SERS detection of antibiotic levofloxacin molecules

The abuse of antibiotics in animal husbandry has been regarded as a daunting public health risk, facilitating the emergence and spread of resistant pathogens to humans. Herein, bimetallic Au@Ag core-shell nanorods (NRs) with precise, controllable Ag shell-thickness (2.1~14.1 nm) were fabricated and developed for ultralow detection of levofloxacin molecules using surface enhanced Raman scattering spectroscopy (SERS). We found that the Au@Ag NRs with 7.3 nm Ag shell-thickness provided maximized SERS activity in comparison with other as-prepared nanosubstrates in this paper. The detection limit of levofloxacin molecules was achieved at a nanomole (nM) level of 0.37 ng/L (10^-9 M), providing ultrasensitive assessment of antibiotics in natural ecosystems.