Nanoplasmonic Imaging of Latent Fingerprints and Identification of Cocaine

摘要

Fingerprints are impressions of the friction ridges of all or any part of a human finger. When a finger touches a surface, eccrine sweat, together with oily substances picked up by the finger, forms an impression of the finger's ridge pattern. Such an impression is known as a latent fingerprint (LFP) for its invisibility to the naked eye. The uniqueness and invaria-bleness of an individual's fingerprint have long been recognized as important physical personal identification, and is hence widely used in individual credentials, access control, and forensic investigation. On the other hand, researchers have realized that fingerprints carry more biological information about individuals than just their identity. The secretions, skin oils, and dead cells in LFPs contain residues of various chemicals and their metabolites present in the human body. These can be detected and used for forensic purposes. Therefore, the imaging of LFPs has found new applications in forensic fields, such as identifying drugs and drug metabolites, residues of explosives, and other secreted chemicals. For this purpose, there has been an intense interest to develop enhanced LFP imaging methods with various spectroscopic and microscopic techniques, for example, mass spectrometry,fluorescence spectroscopy, vibrational spectroscopy (infraredand Raman), electro-chemiluminescence,and scanning electrochemical microscopy.Herein, we report a conceptually new nanoplasmonic approach to provide high-resolution dark-field microscopy (DFM) images of LFPs, as well as the ability to identify cocaine in LFPs by using aptamer-bound Au nanoparticles (AuNPs) as imaging and recognition probes.