Assembly of Magnetic Nano-Fe3O4@GSH-Au NCs Core–Shell Microspheres for the Visualization of Latent Fingerprints

Glutathione (GSH), the protective agent and reducing agent, has been widely used to prepare gold nanoclusters (GSH-Au NCs) with stable fluorescence properties and negative charge of the surface. Meanwhile, polyethyleneimine (PEI) was used as the modification agent to synthesize magnetic ferroferric oxide nanoparticles (Fe3O4) with fantastic dispersibility and positive charge of the surface. Based on the electrostatic adsorption force, magnetic nano-Fe3O4@GSH-Au NCs core–shell microspheres composed of magnetic Fe3O4 nanoparticles modified by PEI as the core and GSH-Au NCs as the shell were assembled. The prepared Fe3O4@GSH-Au NCs microspheres harbored a uniform size (88.6nm), high magnetization (29.2emu/g) and excellent fluorescence. Due to the coordination bond action between Au atom and sulfhydryl (–SH), amino (–NH2), carboxyl (–COOH) in sweat, Fe3O4@GSH-Au NCs could combine with latent fingerprints. In addition, Fe3O4@GSH-Au NCs with good fluorescence and magnetism could detect fingerprints on various o...