New luminescent nanoparticles based on carbon dots/SiO2 for the detection of latent fingermarks

Abstract

This article explores the application of a newly developed non-toxic mesoporous hybrid of carbon dot silica microspheres (CDs/SiO₂) in the detection of latent fingermarks. The CDs/SiO₂ was synthesized from silane-functionalised carbon dots (Si-CDs) and tetraethyl orthosilicate (TEOS) as precursors. The nanoparticles had a spherical morphology with an average diameter of 141 nm, which was advantageous as they emitted tunable fluorescence in accordance with various excitation wavelengths. It was concluded that CDs/SiO₂ nanoparticles exhibited salient selectivity and sensitivity with regard to the detection of fingermarks in realistic substrates such as glass, aluminum foil, plastic bags, drug packing and leather. Moreover, developed fingermarks with good clarity of ridges and excellent contrast can be viewed upon excitation with a 415 nm light source and a yellow filter. In particular, the new nanoparticles are effective and sensitive for both fresh and aged fingermarks, even for those up to two months old. Compared with conventional luminescent powders, these nanoparticles are less likely to float, to aggregate or to stain the background when treating fingermarks. With their ease of operation, non-toxicity, eco-friendly properties, excellent optical performance and good results, CDs/SiO₂ nanoparticles have been proven to hold great promise for the future for the detection of fingermarks.