Bacteria-targeting BSA-stabilized SiC nanoparticles as a fluorescent nanoprobe for forensic identification of saliva.

Forensic saliva identification represents an increasingly useful auxiliary means of crime investigations, particularly in sex crimes. Salivary bacteria detection techniques have been shown to be viable methods for identifying the presence of saliva. A one-pot method is described for the fabrication of bovine serum albumin-stabilized SiC nanoparticles (SiC@BSA NPs). The SiC@BSA NPs were conjugated to antibacterial peptide GH12 to allow for fluorometric detection and imaging of bacteria in saliva. More specifically, the nanoprobe, with fluorescence excitation/emission maxima at 320/410 nm, was used to detect the oral bacteria S. salivarius levels. The detection limit is 25 cfu·mL, and the assay can be performed within 40 min. The nanoprobe was also used to detect bacteria in forensic body fluids including blood, urine, and semen. In all cases, positive results were obtained with (mixed) samples containing saliva, while other saliva samples without saliva showed negative results. Fluorescent images of S. salivarius cells were obtained by implementing a high-content image analysis system. These results suggest that this new nanoprobe can be applied to screen for forensic saliva stains. Graphical abstractSchematic representation of the preparation of SiC@BSA-GH12 nanoprobe for fluorometric detection and imaging of S. salivarius in saliva.