Harnessing hetero-atom doped CQDs from Pyrostegia venusta for latent fingerprint and anti-counterfeit applications

Abstract

The development of innovative techniques for latent fingerprint (LFP) analysis and anti-counterfeiting applications is crucial for addressing various societal challenges. Quantum dot (QD)-based fluorescent staining offers a promising approach due to its high sensitivity. However, the toxicity of traditional heavy metal-containing QDs necessitates the exploration of eco-friendly alternatives. This study presents a facile and environmentally sustainable method for synthesizing heteroatom (nitrogen, phosphorus, and potassium)-doped carbon quantum dots (N-P-K@CQDs) derived from the flower extract of Pyrostegia venusta. Characterization revealed spherical CQDs with an average size of approximately 4.7 nm, a quantum yield of 25 %, and excellent water solubility, photostability, and greenish-fluorescent properties. N-P-K@CQDs were incorporated into a cornstarch nanocomposite phosphor, which exhibited greenish fluorescence under UV excitation. The nanocomposite was utilized as a fluorescent marker for LFP analysis using a customized smartphone-based dactyloscope. Pythonbased image processing algorithms were employed to enhance and analyze the fluorescence images of the developed LFPs. Additionally; a proof-of-concept anti-counterfeiting tag was demonstrated using CQDs-based ink, enabling the detection of concealed security marks. The findings highlight the potential of eco-friendly NP-K@CQDs as a versatile platform for both LFP analysis and anti-counterfeiting applications.