High-affinity Fe3O4/Au probe with synergetic effect of surface plasmon resonance and charge transfer enabling improved SERS sensing of dopamine in biofluids

Development of analytical methods allowing sensitive determination of neurotransmitters in different biofluids is vital. However, there is the limitations related to the impurity interference and stringent requirements concerning the sample purity. Herein, this paper report a strategy for the fast and sensitive analysis of dopamine (DA) in different biofluids with smart Surface-enhanced Raman spectroscopy (SERS) probe composed of magnetite Fe3O4 and Au nanoparticles (Fe3O4/Au NPs). Besides the simple and quick separation of DA from the specimen, Fe3O4 not only enables the specific chemical interaction towards DA molecules, but also acts as the SERS substrates capable of electromagnetically enhancing the Raman signal of DA. Therefore, the Fe3O4/Au NPs composite with coexistent electric-field effect and charger transfer (CT) enhancement is beneficial to capture the target molecules in biological environments and then enhance the DA sensitivity. To interpret strong binding interaction between Fe3O4/Au and DA, the X-ray photoelectron spectroscopy (XPS) has been carried out to illuminate the chemical adsorption or possible CT complex. Moreover, the rapid purification strategy for further separating DA from serum is developed, thus the high sensitivity with nM level is achieved. In addition, the feasibility utility of Fe3O4/Au combined with the developed purification method have also been verified using the different tissues homogenate spiked with DA molecules. Such a nanocomposite can offer the possibility of efficiently separating DA from the complex specimen and then provide the sensitive detection of DA involving in various tissues. Accordingly, the smart SERS probe Fe3O4/Au nanocomposite with the advantages of simple pre-treatment and synergetic enhanced mechanisms promises a great prospect toward a rapid and sensitive detection of DA in complicated specimen.