Combination of electrospray deposition technology of TiO 2 nanoparticles and MALDI FTICR MSI for identification of fingerprint morphology and latent components.

In fingerprint recognition, besides the physical shape information afforded by fingerprint enhancement techniques (FET), in recent years, more and more efforts are focused on researching the chemical composition of a fingerprint residue. In this work, electrospray deposition method was elaborately used to softly and homogenously deposit the physical enhancers of FET, TiO2 nanoparticles (TiO2 NPs), onto fingerprints. The results showed that this type of deposition was nondestructive to the fingerprint morphology and provided the physical shape information containing all level features. Concurrently, the TiO2 NPs demonstrated as a better matrix of matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) for analysis and imaging of latent components in fingerprint, including endogenous substances like triacylglycerols (TAGs), diacylglycerols (DAGs) and cholesterol esters (CEs), and exogenous substances such as certain ingredients in hand lotion. The chemical compositions in fingerprint are closely related to individual metabolites and individual lifestyles, and identification of these compositions by Fourier transform ion cyclotron resonance (FTICR) MS is extremely beneficial for forensic analysis. The combinations of electrospray deposition technology of TiO2 NPs and MALDI FTICR MSI for identification of fingerprint morphology and latent components provide dual-modes fingerprint recognition for forensic science.