A water-soluble
probe, TPA-1OH, with aggregation-induced emission
activity is synthesized and used for expedient real-time fluorescence in situ visualization of latent fingerprints (LFPs). A TPA-1OH
aqueous solution exhibits nonfluorescence in pure water while strong
fluorescence upon molecular aggregation induced by addition of poor
solvent. Fluorescence images of LFPs on a variety of substrates, including
rough surfaces such as walls, bricks, and paper, are developed under
405 nm light, by soaking in or spraying with a TPA-1OH aqueous solution
(30 μM) without any necessity of organic cosolvents and post-treatment
steps. The probe is noncytotoxic at a concentration lower than 50
μM. The development process of LFPs is demonstrated by real-time
fluorescence in situ imaging. The exponential relationship
between the relative fluorescence intensity and time is deduced from
the fitting curve. The LFP images developed by TPA-1OH are evident
and intact enough to allow that the level 1–3 details are displayed
and analyzed. Noteworthily, the level 3 details of LFPs such as the
fingerprint ridge width and the characteristics of the sweat pores
are evidently visible under fluorescence microscopy. Even the nanoscopic
details exceeding level 3 are visualized under super-resolution microscopy
with sub-50 nm optical resolution.
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