Fluorescent Cationic Conjugated Polymer-Based Adaptive Developing Strategy for Both Sebaceous and Blood Fingerprints

Area of Science:

• Forensic Science
• Materials Science
• Chemistry

Background:

• Latent sebaceous and blood fingerprints are crucial in forensic investigations.
• Current methods often require pre-distinguishing fingerprint types, complicating analysis.
• Developing a universal detection method is essential for efficient forensic analysis.

Purpose of the Study:

• To develop a novel, adaptive strategy for detecting both latent sebaceous and blood fingerprints simultaneously.
• To synthesize a cationic conjugated polymer for fingerprint visualization.
• To evaluate the effectiveness of the developed strategy on various nonporous substrates.

Main Methods:

• Synthesis of a cationic conjugated polymer: poly[p-(phenylene ethylene)-alt-(thienylene ethynylene)] backbone (PPETE-NMe3+).
• Preparation of a developing solution using the synthesized polymer dissolved in N,N-dimethylformamide (DMF).
• Application of a simple dropping and incubating process for fingerprint development without pre- or post-treatments.

Main Results:

• The adaptive developing strategy successfully detected both latent sebaceous and blood fingerprints on nonporous substrates.
• Fluorescent photography confirmed the effectiveness of the method.
• Gray value analysis indicated enhanced legibility of the developed fingerprint images.
• Preliminary mechanistic studies suggested synergistic contributions from hydrophobic and electrostatic interactions.

Conclusions:

• The developed adaptive strategy offers an efficient and universal approach for visualizing latent fingerprints.
• The molecular design of the polymer and solvent choice are key to the system's adaptiveness.
• This method holds potential for broader applications in forensic science.