Silver nanoparticle-coated polydopamine-copper hybrid nanoflowers as ultrasensitive surface-enhanced Raman spectroscopy probes for detecting thiol-containing molecules

In this study, silver nanoparticle-coated polydopamine-copper phosphate hybrid nanoflowers (Ag-PDA-Cu3(PO4)2 NFs) were synthesized and demonstrated to serve as efficient surface-enhanced Raman spectroscopy (SERS) probes for detecting thiol-containing molecules such as benzenethiol and thiocholine. Ag-PDA-Cu3(PO4)2 NFs were fabricated by forming PDA-Cu3(PO4)2 NFs through the nucleation of Cu3(PO4)2 on the PDA surface via interaction between Cu2+ and the free amine groups of dopamine, followed by the anisotropic growth of Cu3(PO4)2 crystals into flower-like microparticles. The NFs were then incubated with silver nitrate for in situ reduction to form Ag nanoparticles (NPs) on the surface of the NFs. The resulting hybrid NFs were demonstrated to act as SERS probes, sensitively detecting thiol-containing molecules, based on the successful interaction between Ag NPs and the thiol group (S-H) of the target molecules. The SERS intensities of benzenethiol and thiocholine at various concentrations were analyzed and found to yield superior limits of detection of 800 and 60 pM, respectively. Therefore, Ag-PDA-Cu3(PO4)2 NFs could be excellent SERS probes for detecting various thiol-containing molecules, particularly to determine the status of patients exposed to thiol-containing pesticides.