Surface Enhanced Raman Spectroscopic Investigation On The Identifications Of Fingerprints

Fingerprint is one of the most common and important trace evidence in forensic science because of its uniqueness and the chemical information in the fingerprint involving endogenous and exogenous substances.It is of great value in recovering pattern and extraction of chemical information in the fingerprint.Therefore development of a high-efficiency analysis approach for imaging and extraction of chemical residues is highly desired.Surface enhanced Raman spectroscopy(SERS)has been developed as a promising approach for identification of fingerprint due to its ultrahigh sensitivity.In our research,a new approach was developed to transfer and recover the pattern of living/latent fingerprints based on SERS technique and adhesive Au nanofilm(ANF).Such method was a promising tool in visualization of fingerprints and monitoring of trace chemical residues in forensic science.The main contents are as follows:1.The adhesive ANF was prepared to extract fingerprints and residues,and was capable for SERS imaging.ANF was acquired by the transfer of Au monolayer film to the adhesive side of a tape.Such substrate exhibits several advantages including high SERS activity,excellent uniformity,as well as flexibility and stickiness.It allowed realization of extraction and SERS detection of ink,pesticide residue on the surface of fruits and vegetables and chemical residues in fingerprints.2.SERS mapping was performed to visualize the pattern with characteristic spectra of endogenous substance within the fingerprint.The pattern of living fingerprints together with the third level details was recovered based on the SERS mapping of band at 1640 cm-1 which was assigned to the vibration of amide I band from the endogenous substance of protein.In addition,chemical residues in the living fingerprint,such as dyes,drugs,pesticides and other chemicals were extracted for SERS detection.Such technique of high sensitivity could be applied to monitor the distribution of chemical residues.3.An approach of visualization and extraction of chemical information in latent fingerprint was developed using Rhodamine 6G(R6G)as a developing agent.SERS mapping was performed after transferring the latent fingerprint with ANF.In order to improve the efficiency of latent fingerprint identification,R6 G was introduced to enhance the visualization of latent fingerprints based on SERS mapping.In addition,SERS mapping was carried out for analyzing and visualization of latent fingerprints with high content of chemical residues.