Immunological Multimetal Deposition for Rapid Visualization of Sweat Fingerprints

Recent Progress in Visualization and Analysis of Fingerprint Level 3 Features

Fingerprints provide sufficient and reliable discriminative characteristics which have been considered one of the most robust evidence for individualization. The limitation of current minutiae-based fingerprint technology seems to be solved with the development of level 3 features since they can offer additional information for problematic fingerprint recognition and even donor profiling. So far, tremendous efforts have been devoted to detecting and analysing the third-level details. This review summarizes the advances in level 3 details with an emphasis on their reliability assessment, visualization methods based on physical interaction, residue-response, mass spectrometry and electrochemical techniques, as well as the potentiality for individualization, donor profiling and even other application scenarios. In the end, we also give a personal perspective on the future direction and the remaining challenges in the third-level-detail-related field. We believe that the new exciting progress is expected in the development of level 3 detail detection and analysis with continued interest and attention to this field.

Visualization of latent fingermarks on fabric using multi-metal deposition (MMD)-A preliminary study

Multi-metal deposition (MMD) is a versatile fingermarks detection technique adapted from the colloidal gold biolabeling. However, the tedious procedures of MMD makes it receive little attention compared with other methods. The aim of this study is to evaluate the efficacy of MMD technique on several common fabrics, which is considered notoriously challenging for latent fingermark detection. Four different MMD formulations were examined to process fingermarks deposited on nylon taffeta, polyester taffeta, polyester pongee and cotton sateen to determine the most suitable one and the influence of aging and water immersion were also determined through subsequent experiments. It was found that MMD I outperformed other three formulations and obtained excellent results on nylon taffeta, polyester taffeta and satin ribbon, with polyester taffeta and satin ribbon providing more than 30% of identifiable marks even for fingermarks aged over 28 days. Cotton sateen and oxford cloth failed to produce ridge details but evidence of "touch" were successfully visualized, which may contribute to further DNA extraction. Water immersion did have some observable influence on the quality of detected marks as part of the MMD reactant within fingermarks lost during immersion, but the result from nylon taffeta and satin ribbon is still satisfying with the percentage of marks scored 3 and 4 reached 30%. The result of this study confirmed the capability of MMD I in treated with fingermarks on several kinds of fabrics, and shows potential to promote this non-instrumentation dependent technique.

Recent advances in the chemical imaging of human fingermarks (a review)

This review highlights the considerable advances in the chemical imaging of human fingermarks that provide more chemical information, including numerous endogenous and exogenous constituents. Despite remarkable development in DNA analysis and recognition, human fingermark analysis remains one of the priority approaches available for obtaining reliable forensic evidence. Additional information about the donor can be obtained from the chemical composition of latent fingermarks in addition to the ridge pattern, such as the age, gender, medical history, and possible drug habits. The analytical approaches reviewed here include spectroscopy, mass spectrometry, immuno-labelling and electrochemical methods. Each method has different capabilities with respect to sensitivity, reproducibility, selectivity, reliability and ultimately applicability, either for use in routine forensic practice or in academic research work. The advantages of spectroscopic techniques, including infrared, Raman and micro-X-ray fluorescence spectroscopy, are the capabilities of a rapid and non-destructive imaging of fingermarks by providing spectral information on chemical composition. In addition, mass spectrometry imaging can provide spatially specific information on fingermark chemical composition. Recently, the use of immuno-labelling in latent fingermark detection has attracted significant attention because it can overcome the sensitivity and selectivity problems experienced with other existing methods. The electrochemical method has also been employed to image latent fingermarks by measuring the electric current changes with the spatial chemical composition from the ridges and valleys at high resolution to provide a third level of detail, which is especially useful for multicoloured background surfaces or for surfaces contaminated with blood or other bodily fluids.

Reversible Response of Luminescent Terbium(III)-Nanocellulose Hydrogels to Anions for Latent Fingerprint Detection and Encryption

Fingerprint fluorescence imaging has become one of the most prominent technologies in the field of forensic medicine, but it seldom considers the security protection of detection information, which is of great importance in modern society. Herein we demonstrate that luminescent Tb^III -carboxymethyl cellulose (CMC) complex binding aptamer hydrogels that are reversibly responsive to ClO^- /SCN^- can be used for the selective detection, protection, and storage of fingerprint information. The imaging information of the fingerprint can be quenched and recovered by ClO^- /SCN^- regulation, respectively, resulting in reversible on/off conversion of the luminescence signals for the encryption and decryption of multiple levels of information. The present study opens new avenues for multilevel imaging, data recording, and security protection of fingerprint information with tunable fluorescent hydrogels.