Portable nebulization of water-soluble multicolor AIEgens: Featuring a UV-activatable probe for brightness-enhanced latent fingerprint visualization on diverse substrates.

Latent fingerprint (LFP) detection using aggregation-induced emission (AIE) dyes faces challenges such as dependence on organic solvents and insufficient brightness for faint residues. To address these limitations, a series of amphiphilic tetraphenylethene (TPE)-based compounds exhibiting AIE characteristics have been synthesized. These compounds, which demonstrate excellent water solubility, all incorporate hydrophilic pyridine ethanol-derived groups. Their molecular design was primarily achieved through two strategies: (1) modifying the benzene rings of the TPE framework with substituents possessing different electron-donating or electron-withdrawing properties (TPE derivatives: TPE-2Py-2OH, 2MeO-TPE-2Py-2OH, TPE-2aPy-2OH, 2MeO-TPE-2aPy-OH, and TPE-2TCNPy-2OH), and (2) directly attaching pyridine ethanol-derived groups onto the C=C double bond to confer photoactive properties (TPE analogues: 3PhPyOH and 2Ph2PyOH). Structural modifications enabled a fluorescence emission shift from blue to red, thereby facilitating the selection of suitable probes for substrates with diverse fluorescent backgrounds. Furthermore, a portable nebulizer system was developed, capable of uniformly depositing aqueous solutions of these probes onto various substrates. Notably, high-contrast LFP images containing Level 3 details can be visualized in real time within 10 s using the nebulizing method. Specifically, the aqueous solution of 3PhPyOH demonstrates substrate adaptability and captures Level 3 fingerprint details with increasing brightness upon prolonged UV irradiation, attributed to the restricted intramolecular motion during the photoactivation-induced transformation (from 3PhPyOH to the newly formed compound Uv-3PhPyOH). This strategy effectively overcomes solvent dependency, enhances imaging resolution, and offers a practical and rapid solution for forensic investigations, highlighting the promising application of photoactivatable AIEgens in LFP detection.