In-situ Visualization of Level 3 LFPs Using a Lipophilic Red AIE Fluorescent Probe with a D-A Structure.

Fingerprints are among the most commonly encountered forms of forensic evidence. However, current databases require relatively complete fingerprints to extract sufficient level 2 features for individual identification, thereby limiting the recognition of partial latent fingerprints (LFPs) collected from crime scenes. Therefore, visualizing level 3 features of LFPs (such as width, spacing, and distribution of ridge and pore) is of critical importance. In response to this challenge, this study developed a near-infrared AIE fluorescent probe (D-TPA-A-TXO) with a D-A structure. In ethanol/water binary solvents, D-TPA-A-TXO enabled rapid and distinct in-situ visualization of level 3 LFPs features across various substrates. Owing to its lipophilic nature, D-TPA-A-TXO rapidly dissolved from the solution into the lipid components of LFPs and continuously aggregated. Through the aggregation-induced emission (AIE) effect, high-resolution images of level 3 LFPs features could be directly captured by a standard camera. This advancement provides crucial technical support for enhancing the matching capability of partial fingerprints in future criminal investigations.