Visualizing Fingerprints on Porous Objects by an Optical Sensor Minimally Destructive to DNA Based on Aggregation‐Induced Emission

Development of latent fingerprints (LFPs) at the scene played the important role in forensic investigations by reconstructing crime trajectory and individualizing suspect. In this work, the optical sensor named TPE-LL with aggregation-induced emission property was constructed and used in LFPs visualization. The sensor exhibited a satisfactory linear relationship to tryptophan (Trp) in the range of 1-20 nM with the low detection limit of 0.15 nM. The samples were collected from 60 volunteers, with a total of 7200 impressed samples and 160 natural samples. Significantly, the high-resolution fingerprints images with high fidelity and contrast containing pore features were obtained from impressed samples left on porous object for 15 days. Meanwhile, the relative complete STR typing profiles of deposited DNA were obtained and the identification rate of DNA after the develop process was 76.5 %, suggesting that the method was low destructive to DNA. The results indicated that the sensor provided promising perspectives on solving the current technical problems in the field of forensic science and technology In the sections that follow, this paper provides a brief overview of the optical sensor TPE-LL constructed for visualizing latent fingerprints by detecting tryptophan (Trp) followed by more detailed discussions regarding its development and performance. The friction ridges of fingerprints can be clearly observed under 370 nm excitation wavelength with low-destructive DNA.image