Multi-target-responsive AIE material for in situ visualization of level 3 features in latent fingerprints

The development of level 3 features of latent fingerprints (LFPs), such as the shape of ridges and the size of sweat pores, plays a pivotal role in enhancing the matching of damaged fingerprints. However, most current LFP developers exclusively target lipids and typically require mixed-solvent systems, neglecting critical components like amino acids. This limitation, coupled with the inherent degradation of LFP components over time, hinders the reliable visualization of Level 3 features across diverse fingerprint states. Consequently, the development of hydrophilic, multi-target-responsive AIE materials represents a critical advancement in forensic individual identification.

We report the design of a cationic amphipathic AIE material with -COOMe groups (AIE-COOMe) that can visualize multiple target secretions to produce PL images of level 3 features using an aqueous solution under visible light. In single-component fluorescence assays, AIE-COOMe demonstrated selective targeting toward amino acids (glycine, D-phenylalanine, l-tryptophan), proteins (lysozyme, keratin), and lipids (cholesterol, oleic acid-triglyceride mixtures), enabling accurate visualization of LFPs despite dynamic variations in their secretion composition. DFT calculations revealed that the -COOMe groups enhance hydrogen-bonding interactions, facilitating selective anchoring to amino acid-containing compounds. Furthermore, hydrophobic interactions and electrostatic forces were identified as key mechanisms driving lipid targeting and subsequent aggregation-induced emission.

This study employed multiple intermolecular forces (including hydrogen bonding, electrostatic interactions, and hydrophobic interactions) to enable rapid anchoring of AIE materials to diverse LFPs secretions. This approach effectively addressed the limitation of poor recognition and imaging associated with reliance on a single type of secretion, thereby establishing a foundation for the precise identification of fragmentary LFPs.