Highly Fluorescent Bio-Synthesized Carbon Quantum Dots for Latent Fingerprint Detection

Area of Science:

• Forensic Science
• Materials Science
• Nanotechnology

Background:

• Conventional latent fingerprint detection methods often involve hazardous chemicals and high costs.
• There is a critical need for sustainable, affordable, and high-quality alternatives in forensic science.
• Spent coffee grounds present an underutilized, eco-friendly source for material synthesis.

Purpose of the Study:

• To biosynthesize nitrogen-doped carbon quantum dots (CQDs) from spent coffee grounds.
• To evaluate the efficacy of these CQDs for high-resolution latent fingerprint detection.
• To establish a sustainable and cost-effective approach for forensic fingerprint imaging.

Main Methods:

• One-step hydrothermal synthesis was employed to create nitrogen-doped CQDs.
• Characterization included UV-Visible, photoluminescence spectroscopy, FTIR, XRD, and TEM.
• The CQDs were applied to various non-porous surfaces for fingerprint visualization.

Main Results:

• Nitrogen-doped CQDs exhibited intense cyan fluorescence (quantum yield 19.73%) and high stability.
• Characterization confirmed CQD morphology, optical properties, and an average particle size of 8.71 nm.
• Detailed fingerprint visualization, including ridge patterns and minutiae, was achieved on marble, glass, aluminium, and metal surfaces.

Conclusions:

• Biosynthesized nitrogen-doped CQDs offer a promising, eco-friendly solution for high-resolution latent fingerprint detection.
• The CQDs demonstrated excellent adherence, sustained fluorescence, and photostability for up to 60 days.
• This approach provides a sustainable, cost-effective, and high-performance alternative for forensic applications.