Forensic Nanotechnology: Engineering Polyaniline Nanocomposites for Latent Fingerprints Development

Developed fingerprints imaging was achieved by dusting using doped polyaniline (PANI) nanocomposites. Substituted anilines of 2,6-dimethyl, 2,6-diisopropyl, 3-nitro, and 2-carboxyl were used in the synthesis of the nanocomposites by oxidative polymerization using gold acid and ammonium persulfate (APS). The nanocomposites were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF), X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). Au-PANI developed latent fingerprints showed better results than APS-PANI developed fingerprints on paper, glass, and stainless steel; better adhesion and good contrast ridge details. Developed fingerprints were imaged using optical microscopy and further studied using EDS and XRF. Latent fingerprints developed with Au-PANI were studied using XRF based on the map of gold and chloride elements. This approach is beneficial for faint or partial fingerprints. Fingerprint ridges were obvious in the chloride and gold images acquired from any position of the developed fingerprints. Novelty and significance of this work comprise the ability to visualize the three levels of fingerprint details of primary, secondary, and tertiary, enhanced contrast, less labor intensive, applicable to porous and non-porous surfaces, and cost effective.