Advances in conjugated polymers for visualization of latent fingerprints: a critical perspective

This article provides an elaborate discussion of reports involving the development of latent fingerprints (LFPs) over the past decades with specific emphasis on the contribution of conjugated polymers (CPs) in the field of forensic science. CPs have been explored in the field of interdisciplinary sciences due to their widespread applications in the fields of imaging, chemical and biological sensors, electronic device, cancer therapeutics, etc. Even in the field of forensic sciences, these CP materials are in a continuous race with the existing technology and newer materials for the detection of fingerprint marks on various surfaces thus assisting in the unravelling of the precise identification of an individual suspect in modern criminology. Due to their excellent photophysical and chemical properties such as low toxicity, ease of functionalization, strong fluorescence emission, high quantum yield, and good optical stability, these CPs can lead to high resolution, and increased sensitivity and selectivity in the imaging of LFPs compared to those developed by traditional tedious methods. In this perspective, the challenges faced for LFP development and the role of various CPs including conjugated polyelectrolytes, polymer dots, and polymer nanoparticles are elaborately explained, thus, providing a systematic overview on techniques based on CPs as contrasting agents in the development of LFPs on various porous and nonporous substrates. There are various challenges pertaining to the development of LFPs on a multitude of surfaces which can be addressed by exploring materials with a suitable hydrophobic-hydrophilic balance and a receptor site for specific interactions with fingerprint components. The incorporation of this design principle has successfully led to the development of efficient platforms for rapid, onsite, intricate and unique LFP patterns on every kind of surface.