Trace detection of ciprofloxacin antibiotic using surface-enhanced Raman scattering coupled with silver nanostars

In recent years, the abuse of antibiotics in livestock and aquaculture has become a global concern, so the detection of antibiotic residues in food is a topic of growing interest. At present the surface-enhanced Raman scattering (SERS) technique is promising as a useful tool in trace detection of chemical substances including antibiotics. In this report, we present the trace detection of ciprofloxacin – a widely used antibiotic by recording its SERS spectrum, using a SERS substrate made of silver nanostars (AgNSs) coated on an aluminum foil. In turn, AgNSs are colloidal star-shaped silver nanoparticles that have been very simply synthesized by a two-step chemical reduction of silver nitrate in an aqueous solution at room temperature with hydroxylamine followed by trisodium citrate. The synthesized AgNSs have a total size of 250–300 nm with many pointed arms of 60–80 nm length protruding from the central core. It was found that with a SERS substrate assembled from the above AgNSs coated on an aluminum foil, due to the synergistic effect between AgNSs and aluminum foil, the Raman enhancement factor of the SERS substrate was increased significantly. As a result, a SERS substrate with a Raman enhancement factor as high as 4 × 10 9 was created and ciprofloxacin was detected to very low concentrations, with a detection limit of 0.23 ppb.