Real-time visualization of latent fingermarks with level 3 details based on a solid state emissive organic fluorophore using the powder dusting method

Abstract

Herein, we have designed and synthesized a water-soluble organic fluorescent probe (Py-Pr-OH, 3) and applied it for latent fingermarks (LFMs) detection via the powder dusting method. The probe is highly emissive (in the solid state) and amphiphilic in nature with preferred lipophilicity. The pyridyl cation attached to the polar end group enhances its water solubility. The single crystal structure and packing analysis reveals that the absence of π–π stacking interaction in the lattice contributes to the strong solid-state fluorescence of the Py-Pr-OH molecule. LFM images with level 1–3 details (including, ridge pattern, ridge width, ridge size and sweat pore size) on various substrates have been identified with high resolution and low background interference. The LFMs have been developed very quickly (<10 s), and clear pictures with multilevel details are obtained via simple mobile phone photography. The electrostatic interactions between the probe with sebaceous rich FMs enhance the LFM imaging with high contrast, sensitivity, accuracy, and low background interference. Most importantly, details of the fingermark ridge width and the sweat pores are analyzed under SEM.