This work describes the integration of solid-phase microextraction (SPME) and surface-enhanced Raman spectroscopy (SERS) by codeposition of a hybrid consisting of reduced graphene oxide and silver on silver-copper alloy fibers. The morphology and structure of the coating were characterized by a variety of microscopic and spectroscopic techniques that confirmed the hybrid structure of the material. A galvanic-displacement-induced process is assumed to be involved during the codeposition of the hybrid coating on the alloy. In this process, Ag(I) is reduced to Ag(0) by Cu(0), and the presence of conjugated domains in GO facilitates the long-range transfer of electrons from Cu to Ag+. Simultaneously, GO accepts electrons and is converted into RGO. The hybrid coating exhibits a high SERS enhancement factor and good spatial uniformity. The needle-like coated alloy fibers are shown to be a viable tool for non-destructive sampling and SERS-based determination of trace levels of the antibiotics sulfadiazine and sulfamethoxazole in a spiked tissue mimic. The SERS peaks at 1149 cm-1 for sulfadiazine and 1144 cm-1 for sulfamethoxazole are selected as the reference peaks in the quantitative analysis. The linear range is from 0.01 to 100 μg·cm-3. The detection limits are 1.9 ng·cm-3 for sulfadiazine and 4.4 ng·cm-3 for sulfamethoxazole. Graphical abstract Schematic presentation of I: Galvanic-displacement-induced reduction of graphene oxide (brown films) and Ag+ (purple dots) on silver-copper alloy; II: Codeposition of reduced-graphene-oxide (grey films)/Ag (blue stars) on alloy fiber; III: Non-destructive SPME of antibiotics from spiked tissue mimic; IV: SERS detection using Raman spectroscope.
Keywords: Integrated analysis; Microextraction; Molecular dynamic simulation; Raman spectroscopy; Solid-phase microextraction; Spiked tissue mimic; Sulfadiazine; Sulfamethoxazole; Sulfonamide antibiotic; Surface-enhanced Raman spectroscopy.