A rapid and dual-mode visualization of latent and bloody fingermarks using Cr- and Sb-codoped titanium dioxide nanoparticles

In forensic science, the demand for the discovery and extraction of latent fingermarks at crime scenes in a fast and convenient way is still urgent. Herein, a rutile Cr- and Sb-codoped TiO 2 nanoparticle was synthesized via homogeneous precipitation and was characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and X-ray fluorescence. Subsequently, the as-prepared nanoparticle was used to visualize latent fingermarks using a powder dusting method and to enhance the visualization of bloody fingermarks using a small particle reagent method on porous, semiporous, and nonporous substrates. Notably, the anti-ultraviolet property of this yellow nanoparticle was investigated. This intriguing property contributed to the detection of latent fingermarks on strong-fluorescence or multicolored surfaces in a negative-image manner. Moreover, two potential interaction mechanisms were proposed between hemoglobin and surfactants in bloody fingermark enhancement. This work showed that this rutile TiO 2 nanoparticle doped with Cr and Sb is a versatile eikonogen for the rapid visualization of latent and bloody fingermarks and has high sensitivity, selectivity, contrast as well as wide applicability compared with traditional developing methods.