Overcoming ACQ: DPA-modified TICT-type AIEgens for high-resolution and multilevel latent fingerprint visualization

Abstract

Latent fingerprints (LFPs), as critical carriers of personal identification information, present a long-standing challenge for high-resolution imaging in forensic science. Aggregation-induced emission luminogens (AIEgens), known for their superior luminescence in aggregated or high-viscosity environments, have emerged as ideal candidates for high-contrast fingerprint visualization. In this study, we designed a series of novel AIEgens by introducing diphenylamine (DPA) donor groups at the 3- and 11-positions of a quinazolinone core, effectively constructing twisted intramolecular charge transfer (TICT) systems. This design strategy successfully transformed traditional aggregation-caused quenching (ACQ) behavior into pronounced AIE characteristics. The resulting molecules exhibit intense blue fluorescence, ultralong phosphorescence lifetimes, and a distinct “turn-on” fluorescence response in the presence of lipids secreted by eccrine glands. These features enable high-resolution visualization of level 1–3 fingerprint details on various smooth substrates, offering a promising approach for sensitive and nondestructive fingerprint identification.