Metal Nanoclusters Unlock Latent Fingerprint Visualization

ABSTRACT

Visualizing latent fingerprints (LFPs) with high efficiency constitutes a critical technological challenge in forensic identification and anti‐counterfeiting applications. Conventional fluorescent powders suffer from inherent limitations, including low emission efficiency, restricted spectral range, and pronounced susceptibility to background interference. In this study, three bright nanoclusters Ag ₆ , Ag ₂ Cu ₄ and Cu ₆ stabilized by dual‐site (S, N) ligands, were constructed, enabling tunable nanocluster emission wavelengths spanning from green to red light through precise modulation of the metal core. These M ₆ nanoclusters feature photoluminescence quantum yields of 60%–96% and ultrasmall particle size (< 2 nm), which are leveraged for visualizing LFPs. Compared with commercial fingerprint powder, the M ₆ nanoclusters exhibit higher fingerprint resolution. Even level 3 features of LFPs, including sweat pores, are clearly visible under a microscope. Mechanism studies reveal the multimodal interactions between specialized dual‐site (S, N) ligands and fingerprint residue components (fatty acids, amino acids, etc.), enabling these M ₆ nanoclusters to capture multi‐level detail features of LFPs and demonstrate satisfactory performance across complex substrate scenarios. This work overcomes the inherent limitations of traditional fluorescent materials, showcasing the advantages and potential of metal nanoclusters in LFPs detection applications.