Fluorescent metal organic frameworks for the visual enhancement of latent fingermarks

Abstract

Lanthanide-based (Eu and Tb) metal organic frameworks (MOFs) synthesized in this work are highly fluorescent crystalline structures that form through a self-assembly process in an aqueous environment. Various bio-organic molecules, including proteins and amino acids, can act as inducing agents for this process. The fact that these components are present in fingermark secretions, in combination with the excellent luminescent properties of the MOFs, create a visualisation method for (latent) fingermarks. The aqueous MOF precursor solutions are not ideal for the visualisation of latent fingermarks on non-porous surfaces, such as aluminium foil and glass. However, they offer a simple, non-toxic, long-lasting and effective approach for the visibility enhancement of fingermarks treated with cyanoacrylate fuming on aluminium foil and glass and latent fingermarks on the adhesive side of a transparent tape. The luminescent properties of MOF-treated fingermarks persevered for at least 12 months, providing great alternative for commonly used organic dyes such as Basic Yellow 40 and Gentian Violet. In this communication we evaluate the applicability of the proposed method for the forensic fingermark workflow.