Systematic study of dye loaded small mesoporous silica nanoparticles for detecting latent fingerprints on various substrates

Uniform mesoporous silica nanoparticles (MSNs) with small particle size of ca. 50 nm were fabricated and used as a novel developing agent for latent fingerprints detection. Methylene blue (MB) molecules as a representative dye were loaded in the mesopore of MSNs in order to increase the contrast of the developed latent fingerprints. Both powder and suspension methods composed of MSNs and MSNs@MB were investigated on various substrates, and both of them were able to realize the latent fingerprints development. Moreover, powder method can successfully achieve the detection of the sweat pores (i.e., the typical feature of tertiary structure) of the latent fingerprint, and it has a better effect (i.e., contrast, selectivity and resolution) of latent fingerprints development than suspension methods. In addition, trimethylsilyl (TMS) groups were grafted on the surface of MSNs to increase the hydrophobic nature of particles, but MSNs-TMS@MB had the worse effect of latent fingerprint development than MSNs@MB.