A sensitive surface-enhanced Raman spectroscopy detection for gentamicin and tobramycin using -Al2O3-modified silver nanoparticles coated with bovine serum albumin as substrate

Two aminoglycoside antibiotics (AGs), gentamicin (GEN) and tobramycin (TOB), have good antibacterial activity against most pseudomonas aeruginosa and staphylococcus. The molecular structure of these drugs lack chromogenic groups, which brings challenges to their detection. In this project, the detecting methods for GEN and TOB utilizing surface-enhanced Raman spectroscopy (SERS) based on gamma-Al2O3-modified silver nanoparticles (AgNPs) coated with bovine serum albumin (BSA) were established. The enhancement factors (EFs) of GEN and TOB were 2.44 x 105 and 2.67 x 106, respectively. The transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and spectrophotometric techniques were used to characterize the substrate and the combination of the substance with drugs. The pH, the addition amounts for the substrate and coagulant, as well as the mixing time were optimized. On the basis of single factor experiments, a more scientific response surface model was established. The concentrations of GEN and TOB showed good linear relationships with their Raman signals in the ranges of 6.67 x 10- 8 - 2.00 x 10-6 and 6.67 x 10-9 - 3.00 x 10-7 mol L-1 respectively. The limits of detection (LODs) were 11.88 and 1.26 nmol L-1 for GEN and TOB, respectively. The methods were used successfully for the samples determination of the two AGs in commercial drugs and meat products.