A surface-enhanced Raman scattering method for detection of trace glutathione on the basis of immobilized silver nanoparticles and crystal violet probe

Unsatisfactory sensitivity and stability for molecules with low polarizability is still a problem limiting the practical applications of surface-enhanced Raman scattering (SERS) technique. By preparing immobilized silver nanoparticles (Fe₃O₄/Ag) through depositing silver on the surface of magnetite particles, a highly sensitive and selective SERS method for the detection of trace glutathione (GSH) was proposed on the basis of a system of Fe₃O₄/Ag nanoparticles and crystal violet (CV), in which the target GSH competed with the CV probe for the adsorption on the Fe₃O₄/Ag nanoparticles. Raman insensitive GSH replaced the highly Raman sensitive CV adsorbed on the surface of Fe₃O₄/Ag particles. This replacement led to a strong decrease of the CV SERS signal, which was used to determine the concentration of GSH. Under optimal conditions, a linear response was established between the intensity decrease of the CV SERS signal and the GSH concentration in the range of 50–700 nmol L⁻¹ with a detection limit of 40 nmol L⁻¹. The use of a Fe₃O₄/Ag substrate provided not only a great SERS enhancement but also a good stability, which guarantees the reproducibility of the proposed method. Its use for the determination of GSH in practical blood samples and cell extract yielded satisfactory results.