Functionalization of pyrrole derivatives as a way to improve their solubility in aqueous medium for applying in latent fingerprints development

Interpol review of fingermarks and other body impressions (2019 – 2022)

“…Preliminary/Pilot studies – Redox approaches were proposed to detect fingermarks on cartridge cases or other metallic surfaces: aryldiazonium tetrachloroaurate as redox agent to detect fingermarks on copper [ 405 ] or nickel coins [ 406 ], deposition of cuprous sulphide on unfired brass cartridges [ 407 ]. The electrodeposition of polymers was also proposed to detect fingermarks on various metal surfaces, sebum-rich secretions acting as mask preventing the polymerization process: polycaprolactone nanofibers on aluminium, stainless steel, and cartridges [ 408 ], poly(3,4-ethylenedioxythiophene) on unfired brass cartridges [ 409 ], polyluminol on indium tin oxide coated glasses [ 410 ], poly(neutral red) on platinum and brass [ 411 , 412 ], polypyrrole combined with poly(2,2′:5′,2″-terthiophene) on stainless steel [ 413 ], and polypyrrole derivatives on stainless steel [ 414 ]. Other electrodeposition processes were proposed: cobalt oxide films on stainless steel [ 415 ], copper on aluminium [ 416 ], nickel/phosphor composites on copper [ 417 ].…”

From nanomaterials to macromolecules: Innovative technologies for latent fingerprint development

“…SEM images of a sebaceous latent fingerprint developed by (a) silver imaging ink at lower (100 μm) and (b) higher (10 μm) magnification showing the interaction of the silver ink with the surface (negative image); and (c) P1 electrodeposited onto the fingerprint residue showing second level details (ridge end—red circle, bifurcation—green circle) and d) at higher magnification (20 μm) the edge between lighter and rougher region (positive image). Adapted from Y. Yang et al (2016) and Lyra et al (2021) with permission of The Royal Chemical Society and Elsevier…”

“…As shown in Figure 17a, the spatial pattern of the fingerprint was clearly observed, and the furrows of the latent fingerprints were coated with a compact layer of silver. Lyra et al (2021) have demonstrated that polypyrrole derivatives containing carboxylic acid or sulfonate functionalities may interact with the organic compounds (fatty acids, free amines and amino acids) present in the fingermark residues instead the bare metal surface. SEM images of the polymer P1 functionalized with carboxylic acid are shown in Figure 17b at different magnifications.…”

“…They demonstrate that the portfolio of materials suitable for electrochromic enhancement of latent fingerprints can be extended to include pyrrole‐based modified materials aiming to provide a wider color palette to optimize the developed fingerprint visual contrast against the substrate. Recently, Lyra et al (2021) have synthesized Py derivatives modified with carboxylic acid, ester or sulfonate functional groups aiming at improvement of the solubility of the monomers in aqueous medium and also have prepared a copolymer of a Py derivative, namely sodium S ‐(3‐[pyrrol‐1‐yl]propyl)sulfothioate salt, with EDOT to study the interaction of the as‐electrodeposited polymer/copolymer with the metallic surface (stainless steel) or even with the fingermark residues. Image acquisition (using scanning electron microscopy) and analysis (using specialized software and the UK Home Office grading scale) showed the results to be suitable for forensic identification purposes.…”

“…The technique of choice will depend on desired spatial resolution and observation environment. Ex situ techniques of value include scanning electron microscopy (SEM) (Yang et al, 2016; Lyra et al, 2021; Costa, Assis, et al, 2020), atomic force microscopy (AFM) (Brown & Hillman, 2012; Goddard et al, 2010; Prasad et al, 2019) and transmission electron microscopy (TEM) (Prasad et al, 2021; Pan et al, 2022; Ding et al, 2021). Scanning electrochemical microscopy (SECM) can be used in situ as a tool for visualization of the morphological details of a fingerprint enhanced by MMD technique, where the silver layer on the gold nanoparticles is reoxidized upon the passage of the scanning probe and the image is obtained electrochemically in the feedback mode, originating from the oxidation of IrCl 6 3− added to the electrolyte solution as mediator (Shi et al, 2020; Zhang et al, 2007; Zhang & Girault, 2009).…”