MALDI TOF Imaging of Latent Fingerprints a Novel Biosignature Tool

摘要

This project is aimed to develop novel methodology for latent fingerprints visualization with simultaneous chemical analysis based on MALDI- MSI. The overall objectives of our research program are: (i)Studying of a sweat chemical composition of a group of individuals by HPLC-electrospray Q-TOF and MALDI TOF-TOF mass spectrometry techniques. To assess possibility of fingerprints visualization with simultaneous chemical analysis, a model experiment was performed. Fingers have been lightly coated with ointment containing tocopherol and imprinted on stainless-steal MALDI plate. Application of tocopherol allows efficient laser ionization without use of matrixes or additional treatment of the fingerprint. The result of scan clearly shows that MALDI-MSI is a promising analytical tool with good enough resolution and sensitivity, even for fast-mode of scan and no advanced image processes approaches. No clear fingerprint pattern was achieved for fingerprints without additives. Main reason is lack of efficient method for ionization, spectrometry and data-processing of sweat components. To improve mass spectrometry methods, better understanding of sweat components mass spectrometry is required. Major objective of second phase was characterization of relevant sweat components and MALDI-MS methods optimization. Series of matrixes and deposition techniques was evaluated for fingerprint signal enhancing. The best methodology included use of CHCA matrix and a combination of spray and drop-casting deposition techniques. This procedure allowed MALDI-MS analysis of fingerprint deposited directly on stainless steel plate. In conclusion, we demonstrated the possibility of latent fingerprint visualization with suitable matrix by MALDI- MSI.