Development of cost-effective fluorescent carbon nanoparticles as security ink for anticounterfeiting and fingerprint visualization.

Anticounterfeiting and latent fingerprinting have become ever-growing global demands, impacting national economies, defence and various technological fields. This has led to an increasing need for photoluminescent materials that are nontoxic, highly luminous, photostable, more sensitive and low-cost. However, there is a lack of research reports that offer a detailed exploration of photoluminescent materials for both anticounterfeiting and latent fingerprinting. Thus, we explored waste pistachio shell biomass-derived tunable fluorescent carbon nanoparticles as an invisible/security ink for latent fingerprint visualization and anticounterfeiting labels. Three levels of security characteristics for fingerprint analysis were investigated to enable a more comprehensive exploration of the synthesised fluorescent carbon nanoparticles. The invisible distinctive impression of the ridges, grooves, and furrows of the fingers was visible on the thin layer chromatographic plate after fluorescent carbon nanoparticle-based ink was applied to the finger under UV-light excitation. The anticounterfeiting study was performed after labelling the prepared ink on Whatman filter paper, TLC plates, PVA films and Indian currency to investigate its diversified applications. This study provides a new prospect for low-cost and non-toxic photoluminescent carbon nanoparticles as invisible ink for security, encryption, and labels.