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 (Fe 3 O 4 ) with fantastic dispersibility and positive charge of the surface. Based on the electrostatic adsorption force, magnetic nano-Fe 3 O 4 @GSH-Au NCs core–shell microspheres composed of magnetic Fe 3 O 4 nanoparticles modified by PEI as the core and GSH-Au NCs as the shell were assembled. The prepared Fe 3 O 4 @GSH-Au NCs microspheres harbored a uniform size (88.6[Formula: see text]nm), high magnetization (29.2[Formula: see text]emu/g) and excellent fluorescence. Due to the coordination bond action between Au atom and sulfhydryl (–SH), amino (–NH 2 ), carboxyl (–COOH) in sweat, Fe 3 O 4 @GSH-Au NCs could combine with latent fingerprints. In addition, Fe 3 O 4 @GSH-Au NCs with good fluorescence and magnetism could detect fingerprints on various objects. Significantly, the powders were not easy to suspend in the air, which avoided the damage to the health of forensic experts and the fingerprints by only powder contacting. Above all, Fe 3 O 4 @GSH-Au NCs was successfully applied to the latent fingerprint visualization, which has great potential in forensic science.