Dados do Trabalho

Título

APPLICATION OF FLUORESCENT CARBON NANOPARTICLES (CDOT) IN DEVELOPMENT LATENT FINGERPRINTS

Introdução

Fluorescent carbon nanoparticles – carbon quantum dots (Cdots) - are an emerging class of organic materials with fluorescent properties in the visible spectrum, these structures have low production cost, stable luminescence and biocompatibility (SHABASHINI e colab., 2021). In addition to optical properties, these nanostructures may have different surface characteristics and luminescent emission at long wavelengths depending on the synthesis precursors and the method used. These characteristics have attracted the attention of forensic research for the use of these nanomaterials in the identification of fingerprints, mostly on dark surface.

Objetivos

Evaluate the influence of the surface characteristics and fluorescent spectrum of Cdots in the development of latent fingerprints.

Parte experimental

Two types of nanoparticles were prepared by heating in microwaves, one with citric acid and urea (CdotG) and the other with citric acid and ethylenediamine (CdotB). The materials were characterized by FTIR, MET, UV-vis and Fluorescence. The nanoparticles in aqueous solution were sprayed to the fingerprints, after drying, the surfaces were illuminated with ultraviolet light and photographed to identify the marking regions.

Resultados e Discussões

The Cdots obtained are smaller than 5 nm and interplanar distance of 0.21 nm, typical of graphitic structures, in the FTIR spectra regions of C=O (1700cm-1), N-H (3400 cm-1) and O-H bonds are observed (3500 cm-1) which justifies the high solubility of the nanoparticles, the absorptions bellow of 1600 are typical of C=N and N=O bonds in aromatic structures. Absorption at 249 nm and between 300 and 400 nm are signaled by π-π* and n→π* transitions, respectively, the luminescence spectrum shows emissions dependent on the emission length in the green and blue regions. The surface of the nanoparticles showed high interaction with the wax and fat of the fingerprints after the solvent dried with well-defined marking of the fringes, mainly for CdotG.

Conclusões

The fluorescent carbon nanoparticles obtained in this work show high solubility in aqueous media and when applied by spraying on the surfaces, they showed high selectivity and differentiation of the fringes of the fingerprints, paving the way for the use of these materials.

Referências e agradecimentos

SHABASHINI, Arivalagan e PANJA, Sumit Kumar e NANDI, Ganesh Chandra. Applications of Carbon Dots (CDs) in Latent Fingerprints Imaging. Chemistry – An Asian Journal, v. 16, n. 9, p. 1057–1072, 3 Maio 2021.

Acknowledgment – Financial suppor from the FAPDF.

Palavras Chave

Nanoparticles, luminescent, latent fingerprints.

Arquivos

Área

Áreas forenses