Red-Near Infrared Luminescence Detection of Latent Fingermarks with Heavy-Metal-Free Quantum Dots

Current and proposed nanoparticle-based techniques for development of latent fingermarks suffer a number of drawbacks such as complicated, multi-step and time-consuming procedures, batch-to-batch variability, expensive reagents, large background noise and toxicity. Here, we introduce a promising green development technique based on heavy-metal-free quantum dots (QD) for the detection of latent fingermarks on non-porous surfaces. Red-near infrared luminescent Cu-In-S/ZnS core-shell QDs solution was produced in large scales using a water-based, simple and fast method using N-acetyl-cysteine as a biocompatible surfactant to coat the particles. The coated QDs were applied to the successful development of latent fingermarks deposited on a variety of surfaces, including highly patterned polymer banknotes and the sticky side of adhesive tape.