A pyrene formulation for fluorometric visualization of latent fingermarks

Controlling the Fluorescence Behavior of Hydrophobic Pigments by Supramolecular Self-Assembling on Organic Layered Silicate Minerals

This research focused on the supramolecular self-assembly of organic fluorescent molecules on organically modified layered silicate minerals to design and prepare layered nanocomposites with excellent fluorescence properties. Aromatic hydrocarbons are hydrophobic and poorly loaded on the hydrophilic surface of layered silicate minerals, but they are easily captured by an organically modified mineral surface. Montmorillonite (MMT) and saponite (SAP), typical 2:1 type layered silicate minerals with different octahedral cations, were modified with the cationic surfactant octadecyl trimethylammonium chloride (OTAC) and loaded with pyrene (an aromatic hydrocarbon dye) with different molar ratios to the cationic surfactant by supramolecular self-assembling to construct fluorescent nanocomposites. The effect of pyrene concentration and the octahedral cation of the 2:1 type layered silicate minerals on photoluminescence properties was investigated. The fluorescence spectra of the nanocomposites prepared under low pyrene concentrations showed two bands at around 400 and 470 nm, corresponding to the monomer and excimer emissions; the band intensity of the excimer shoots up with the increase of pyrene concentration, reflecting different contributions from monomer and dimer species and the formation of radical aggregates. The excellent heat resistance of the layered silicate structure can effectively protect pyrene molecules from external environmental influences.

A Facile Microwave-Assisted Green Synthetic Approach of Solid-State Fluorescent Carbon-Dot Nanopowders Derived from Biowaste for Potential Latent-Fingerprint Enhancement

Latent fingerprint detection and visualization remains a challenge especially where problems of poor contrast, auto-fluorescent surfaces and patterned backgrounds are encountered. As a result there is an increasing interest in the development of simple, cost effective, rapid and yet accurate methods for latent fingerprint detection and recovery. Herein, this paper reports the synthesis of bright blue photoluminescent carbon dots (C-dots) via an eco-friendly and simple one-step microwave-assisted carbonization of potato peels’ biomass. The C-dots were prepared in only 3 min and ground into powder and used without any further treatment. The as-prepared C-dots were characterized using atomic force microscope, Fourier transform infra-red spectroscopy and X-ray diffraction with an average size of 1.0[Formula: see text]nm. The optical properties of the as-prepared C-dots were studied by UV-Vis spectroscopy and spectrofluorometer which established an excitation and emission wavelengths of 390[Formula: see text]nm and 480[Formula: see text]nm, respectively. Owing to their strong solid state fluorescence, the as-prepared C-dots’ powder was successfully used in latent fingerprint detection and imaging on porous and nonporous surfaces. Latent fingerprints were recovered with high resolution and excellent quality providing sufficient details for individual identification. These findings demonstrate that C-dots derived from biomass have a great potential in latent fingerprint analysis for forensic applications.

Pyrene Tags for the Detection of Carbohydrates by Label-Assisted Laser Desorption/Ionisation Mass Spectrometry*

Matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS) is widely used for the analysis of biomolecules. Label-assisted laser desorption/ionisation mass spectrometry (LALDI-MS) is a matrix-free variant of MALDI-MS, in which only analytes covalently attached to a laser desorption/ionisation (LDI) enhancer are detected. LALDI-MS has shown promise in overcoming the limitations of MALDI-MS in terms of sample preparation and MS analysis. In this work, we have developed a series of pyrene-based LDI reagents (LALDI tags) that can be used for labelling and LALDI-MS analysis of reducing carbohydrates from complex (biological) samples without the need for additional chemical derivatisation or purification. We have systematically explored the suitability of four pyrene-based LDI enhancers and three aldehyde-reactive handles, optimised sample preparation, and demonstrated the use of LALDI tags for the detection of lactose. We have also exemplified the potential of LALDI tags for labelling carbohydrates in biological samples by direct detection of lactose in cow's milk. These results demonstrate that LALDI-MS is a promising technique for the analysis of reducing carbohydrates in biological samples, and pave the way for the development of LALDI-MS for glycomics and diagnostics.

Interpol review of fingermarks and other body impressions 2016-2019

This review paper covers the forensic-relevant literature in fingerprint and bodily impression sciences from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20 Review%20 Papers%202019. pdf.

Volatilised pyrene: A phase 1 study demonstrating a new method of visualising fingermarks with comparisons to iodine fuming

Pyrene is a fluorescent polycyclic aromatic hydrocarbon that can be volatilised under mild conditions. When fumed, pyrene is rapidly absorbed into the sebaceous residues of fingermarks, enabling their fluorescent visualisation upon excitation with ultraviolet radiation. This new means of fluorescent fingermark detection is more sensitive than the non-fluorescent iodine fuming approach for nonporous surfaces. This is demonstrated here in a phase 1 study using split-print comparisons on metal and glass surfaces. Pyrene-treated fingermarks also retain the volatile fluorophore for comparably long time periods relative to iodine fuming (in the order of hours). The phase 1 study comprised four donors, and 80 natural fingermarks that were grouped into two time periods; aged 24h and 1 week. Iodine fuming was chosen as a reference to showcase the effectiveness of pyrene given it is the most closely-related chemical fuming method in routine use. This study demonstrates that pyrene fuming increases the quantity and quality of fingermark visualisations relative to iodine fuming, and is free of many of the latter method's drawbacks. Preliminary results shown here also show the effectiveness of pyrene fuming on highly patterned surfaces, and its compatibility with the use of gelatine lifters. Pyrene fuming is thus easy to effect, low-cost, and shows great promise as a new means of visualising fingermarks on non-porous surfaces.