- Email: [email protected]
A tetraphenylethene-based dye for latent fingerprint analysis
Accepted Manuscript Title: A Tetraphenylethene-based Dye for Latent Fingerprint Analysis Authors: Xiaodong Jin, Ran Xin, Shifan Wang, Wenzhu Yin, Tongxiang Xu, Yang Jiang, Xuran Ji, Luyang Chen, Jingning Liu PII: DOI: Reference:
S0925-4005(17)30079-5 http://dx.doi.org/doi:10.1016/j.snb.2017.01.080 SNB 21605
To appear in:
Sensors and Actuators B
Received date: Revised date: Accepted date:
13-10-2016 30-12-2016 10-1-2017
Please cite this article as: Xiaodong Jin, Ran Xin, Shifan Wang, Wenzhu Yin, Tongxiang Xu, Yang Jiang, Xuran Ji, Luyang Chen, Jingning Liu, A Tetraphenylethenebased Dye for Latent Fingerprint Analysis, Sensors and Actuators B: Chemical http://dx.doi.org/10.1016/j.snb.2017.01.080 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
A Tetraphenylethene-based Dye for Latent Fingerprint Analysis 1
Xiaodong Jin a, *, Ran Xinb, Shifan Wang c, Wenzhu Yin d, *, Tongxiang Xu a, Yang Jiang a, Xuran Ji a,
Luyang Chen a, and Jingning Liu a, b, *
a. Department of Criminal Science and Technology, Jiangsu Police Institute, Nanjing, Jiangsu, 210031, P. R. China. E-mail: [email protected] (Dr. Jin XD), Tel: +86-025-52881716; [email protected] (Prof. Liu JN) b. Center of Forensic Science and Technology, Bureau of Public Security for Jiangsu province, Nanjing, Jiangsu, 210024, P. R. China. c. School of Chemistry and Chemical Engineering, Xuzhou Institute of Technology, Xuzhou, 221111, P. R. China d. Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China. E-mail: [email protected] (Dr. Yin WZ)
*Corresponding authors： E-mail: [email protected] (Dr. Jin XD), Tel: +86-025-52881716; [email protected] (Dr. Yin WZ); [email protected] (Prof. Liu JN)
1
Highlight
A tetraphenylethene-based probe (FLA-1) was used to develop for recognition of the latent fingerprints on the surfaces of various substrates.
The approach do not need expensive or hazardous reagents, sophisticated instrument, and posttreatment procedures.
The resolution of the fingerprints visualized by the probe FLA-1 is enough to offer a positive match according to the information supplied from a police database.
Abstract A tetraphenylethene-based dye (FLA-1) was used to develop for enhancing the visualization of the latent fingerprints on the surfaces of various substrates. The resolution of the fingerprints visualized by the probe FLA-1 is enough to offer a positive match according to the information supplied from a police database. Experimental results confirm the accuracy of using the probe for LFPs detection.
Key words Fluorescence probe; Tetraphenylethene derivative; Aggregation Induced Emission; the latent fingerprints identification; Criminal science
Fluorescent probes are powerful tools which are important to analytical sensing, and the sensing sensitivity and accuracy of a probe is determined by the brightness and contrast of its fluorescence before and after analyte binding. [1-4] However, many conventional fluorophores are usually faced with a challenge that they will be quenched at high concentrations or in aggregate state. This leads us to what is called the concentration quenching or aggregation caused quenching (ACQ) phenomenon [5]. Evidently, it seems adverse to sense analytes including the latent fingerprints (LFPs), ions, and others. To our delight, the development of the fluorescent materials with high solid-state quantum yield in aggregated state or even in solid state which is known as the aggregation induced emission (AIE) effect of the dyes can solve the problem well. [6-10] So far, a variety of functional materials based on AIE fluorophores have been extensively reported, however, only a limited number of AIE dyes have been applied by visualizing the LFPs.[9-12] Fingerprints have been widely used in many fields, including forensic investigations and personal identification.[13] And, it was considered one of the most valuable physical evidence for identification at crime scenes.[14-17] Numerous efforts have been made in recent years to improve the existing techniques
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for better visualization of the LFPs.[11, 13-14, 18-25] Powder dusting is the most commonly and portably used visualization technique for the LFPs.[26] However, it inevitably associated with serious problems in developing latent fingermarks, such as dust pollution, low sensitivity on wet surfaces and inevitable destruction of the fingerprint details when brushing magnetic or fluorescent powders on LFPs. Additionally, the commercial chemical reagents applied worldwide such as ninhydrin (NH)[27], 1,8diazafluoren-9-one (DFO)[28], often takes several minutes or hours, and cyanoacrylate (CA) unavoidably requires fuming for its deposition on the latter.[29] Therefore, it is necessary to develop some simple, cost-effective and reliable methods for the recognition of the LFPs with satisfactory sensitivity. In reality, it still remains a significant challenge. Satisfyingly, in 2012, Su’s research group first proposed a novel use of the aggregation induced emission (AIE) effect of tetraphenylethene (TPE) for the visualization enhancement of LFPs on wet non-porous surfaces.[9] The strategy presents several obvious advantages. Firstly, the overall process is performed in solutions and does not involve powder or fume treatment. Secondly, it can effective avoid the ACQ phenomenon to some extent of the conventionally employed luminescent dyes are absent. Thirdly, the sensing mechanism of visualizing the LFPs is reliant upon the preferential adhesion of TPE-derivate aggregates to the ridges by hydrophobic - hydrophobic interaction. In view of our interest in AIE-based fluorophores, we use the AIE strategy to recognize the LFPs. Recently, we have successfully developed a facile near infrared (NIR, 650-900 nm) probe NIR-LP based on ESIPT/AIE process for the visualization of the LFPS.[11] In this work, as a part of our on-going research on the visualization of the LFPs, we herein describe the design and synthesis of a simple fluorescent probe FLA-1 based on the TPE derivative for the recognition of LFPs (as shown in Scheme 1). As shown in Scheme 1, the fluorescent probe FLA-1 consists of two moieties: (i) TPE as the fluorescent core which is an archetypal AIE luminogens. (ii) The hydrophobic chain moiety was introduced into the TPE core to improve the hydrophobic property of TPE. Thus, we hope it can improve the hydrophobic - hydrophobic interaction between the TPE-derivate aggregates and the ridges of the LFPs. What’s more, we hope that the resolution of the fingerprints which would be visualized by the probe FLA-1 can be able to offer a positive match with those fingerprints present in databases to satisfy the police or other security agencies demand.
[Insert Scheme 1]
The probe FLA-1 was easily synthesized in good yield by the reaction of 4-(1,2,2triphenylvinyl)phenol with 4-vinylbenzyl chloride in the presence of K2CO3, and characterized by 1H 3
NMR (Fig. S1)and single crystal X-ray analysis (Fig. 1). Details of crystallographic data, selected bond distances, angles and structure refinement are summarized in Table S1.
[Insert Fig. 1] [Insert Fig. 2]
It is well known that TPE is a typical AIE fluorophore and most of the reported TPE-based dyes are AIE-active and emit blue or green light in their aggregated states due to the restricted intramolecular rotation (RIR) mechanism.[1, 5] To explore whether FLA-1 is AIE-active or not, the emission spectra of the dye in CH3CN and CH3CN–water mixture solutions were recorded (Fig. 2). It is clearly seen that the pure CH3CN solution of the dye FLA-1 were almost non-emissive and the fluorescence spectra are nearly parallel to the abscissa. However, the fluorescence intensities abruptly increased when the water volume fraction (fw) was greater 50%. It is probably the value of fw beyond 50% could induce the formation of FLA-1 aggregates, subsequently impeding the intramolecular rotations of the aromatic rotors of FLA-1. Thus, it endows the aggregates with intense emission.
[Insert Fig. 3]
Due to the excellent optical and AIE properties of the probe FLA-1, we intended to explore the application of the probe FLA-1 for potential LFPs imaging. The sebum-rich fingerprint development procedure is fairly simple. Sebaceous latent fingerprints were obtained from volunteers by gently rubbing their fingers over the forehead or nose and then pressing them on different substrates (including aluminium foils, coins and glass slides) to leave fingermarks that contain sebaceous materials (sebum). The fingerprints were typically developed by FLA-1 as follows. The substrate was swayed for an appropriate period of time (20 min) in the CH3CN-water mixtures of FLA-1 with different amounts of water, then gently rinsed with water twice or thrice. This process causes the initially invisible latent fingerprint to become blue-colored and visible to the naked eye (Fig. 3). Because the probe FLA-1 is fluorescent, the well-resolved friction ridge patterns of the latent fingerprint can be observed using a fluorescence microscope (Fig. 3). As a consequence of the fact that a latent sebaceous fingerprint is abundant in fatty acids, favorable hydrophobic interactions between FLA-1 aggregates and lipid, thus immobilizing the FLA-1 on fingerprint ridge structures. In fact, the high quality of the fingerprint images
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obtained by using this technique enables visualization of second level bifurcation, termination, and lake structures which are critical for forensic identification of individuals. Our results show that a fresh latent fingerprint deposited on different substrate surfaces, such as coin (Fig. 3a), glass slide (Fig. 3b), and aluminium foil (Fig. 3c) could be clearly seen when excited with a 365 nm UV lamp, with ridges, furrows, and other details clearly visible.
[Insert Fig. 4]
Subsequently, we make further evaluate the capacity of the dye FLA-1 to visualize the LFPs in other substrate surface (e.g., stainless steel sheet, pop-top can, beverage bottle, black color plastic, train ticket, paper cigarette case and envelop). From the experimental results, we found that the LFPs in stainless steel sheet, pop-top can and beverage bottle could be visualized well, and it display poor resolution in black color plastic and train ticket. However, it seems invisible in cigarette case and envelop. It was probably that the hydrophobicity of the substrate surface will influence the imaging quality of the LFPs fluorescent images. The paper cigarette case and envelop are apparently the most hydrophilic substrate. These results indicate that probe FLA-1 readily interacts with sebum-rich LFPs, especially on smooth surfaces (e.g., coin (Fig. 3a), glass slide (Fig. 3b), aluminium foil (Fig. 3c), stainless steel sheet (Fig. 4a), pop-top can (Fig. 4b) and beverage bottle (Fig. 4c)).
[Insert Fig. 5] [Insert Fig. 6]
In real crime scenes, we are more likely to encounter a problem that whether the latent fingerprint at different objects were left behind by the same criminal suspect or not. Thus we further demonstrate the robustness of the probe FLA-1 for practical use. The procedure carried out in the examination of the different fingerprints was as follows: In order to continue our research on the visualization of the LFPs, we choose a fingerprint that has been successfully recognized by us using the other probe and published in our previous study[11] as a standard fingerprint (a red fluorescent enhancement fingerprint) which was labeled as Reference Fingerprint (abbreviated as R). Then, the R fingerprint was introduced in the
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database of the police and we would obtain a treated picture as a gray-scale image where the ridges appear as light lines, and the furrows are the dark areas between the ridges, showing the enhancement of the images which was labeled as R1. Additionally, the latent fingerprint was detected under UV light and displayed a blue fluorescent enhancement fingerprint which was labeled as Scene Fingerprint (abbreviated as S) in different Figures (Figs. 5-7). All these images (S fingerprints in different Figures) were dimensioned to be suitable for the correspondences. Moreover, the S fingerprint images should be also processed. Namely, the different fingerprints at different objects (e.g. glass, aluminium foil and coin) are used as template images should be processed. And, we labeled these treated image as S1 in all figures (Figs. 5-7). These fingerprints have been introduced in the fingerprint database to be compared in the database and to do the correspondences with R1 fingerprints. After treatments above, we obtain the minutia points of R1 and S1 fingerprints through the computer system, and we get the correspondence fingerprints images which were labeled as R2 and S2, respectively. Fig. 5(a) shows the dimensioned fingerprint treated by probe NIR-LP which has been published by our previous study as the standard fingerprint (R fingerprint). Fig. 5(d) shows the fluorescence enhancement fingerprint (S fingerprint) treated by FLA-1 and irradiated on the surface of a glass. The S2 fingerprint in Fig. 5(f) shows correspondences to the direct images of R2 fingerprint and it was found to have 17 correspondences that the images of R2 and S2 fingerprint have 17 red ○ by one-to-one correspondence.
[Insert Fig. 7]
Other examples of images in non-porous surfaces have been also done, including aluminium foils (Fig. 6) and coins (Fig. 7). As shown in Fig. 6, R2 and S2 fingerprint have different contrast ratios that a total of 42 matching-characteristics (42 red ○ can one-to-one correspondence) were found. The same procedure was carried out with fingerprints taken from a coin (Fig. 7), and applying this simple procedure, 37 correspondences were obtained. It should be noted that the amount of characteristics varies from one to another, and is usually between 8 and 16 matches.[30] These experimental results confirm the accuracy of using the probe for LFPs detection.
Conclusions In summary, we have successfully developed a tetraphenylethene-based dye (FLA-1), which was characterized by 1H NMR and X-ray and by fluorescence spectroscopies, for enhancing the visualization of latent fingerprints on the surfaces of various substrates. The approach is pretty simple and cost-
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effective, upon a single-step treatment and only involves some simple and portable devices. Moreover, the overall process is performed in solutions and does not involve powder or fume treatment. In addition, the resolution of the fingerprints visualized by the dye FLA-1 is enough to offer a positive match according to the information supplied from a police database. Experimental results illustrate the effectiveness of proposed methods. We envisage that the method could be used for various forensic applications. And, a further research work is ongoing that we are polymerizing probe FLA-1 with the relevant monomer to endow the dye some other property, such as sensing the TNT or TNP in LFPs.
Acknowledgements This work was sponsored by the Jiangsu Students’ Platform for Innovation and Entrepreneurship Training Program (No. 201610329022Y and 201610329005Z), the Research Program for Young Scholars of Jiangsu Police Institute (No. 2016SJYZQ02), the Science and Technology Research Program for the Bureau of Public Security of Jiangsu province (No. 2016KX026), and the Science and Technology of Public Security of Jiangsu Police Institute - the Key Construction Disciplines at the Provincial Level of Jiangsu Province during 13th Five-Year Plan (2016-2020).
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ACS. Appl. Mater. Inter. 23 (2016) 14389-14395. [14] G. Qin, M. Zhang, Y. Zhang, Y. Zhu, S. Liu, W. Wu and X. Zhang, Visualization of latent fingerprints using Prussian blue thin films, Chin. Chem. Lett. 2 (2013) 173-176. [15] H.C. Lee, R.E. Gaensslen, Advances in fingerprint technology, 2nd ed., CRC, Boca Raton, 2001. [16] C. Champod, C. Lennard, P. Margot, M. Stoilovic, Fingerprints and other ridge skin impressions, CRC, Boca Raton, 2004. [17] M.R. Hawthorne, Fingerprint analysis and understanding, CRC, Boca Raton, 2009. [18] D. Fernandes, M.J. Krysmann and A. Kelarakis, Carbogenically coated silica nanoparticles and their forensic applications, Chem. Commun. 53 (2016) 8294-8296. [19] J. Gooch, H. Goh, B. Daniel, V. Abbate and N. Frascione, Monitoring criminal activity through invisible fluorescent “peptide coding” taggants, Anal. Chem. 8 (2016) 4456-4460. [20] P. Niu, B. Liu, Y. Li, Q. Wang, A. Dong, H. Hou, L. Zhang, Y. Gao and J. Zhang, CdTe@SiO2/Ag nanocomposites as antibacterial fluorescent markers for enhanced latent fingerprint detection, Dyes. Pigm. 119 (2015) 1-11. [21] K. Wang, Z. Yang and X. Li, High excimer-state emission of perylene bisimides and recognition of latent fingerprints, Chem. Eur. J. 15 (2015) 5680-5684. [22] P. Wu, C. Xu, X. Hou, J. Xu and H. Chen, Dual-emitting quantum dot nanohybrid for imaging of latent fingerprints: simultaneous identification of individuals and traffic light-type visualization of TNT, Chem. Sci. 8 (2015) 4445-4450. [23] B. Shin-Il Kim, Y. Jin, M.A. Uddin, T. Sakaguchi, H.Y. Woo and G. Kwak, Surfactant chemistry for fluorescence imaging of latent fingerprints using conjugated polyelectrolyte nanoparticles, Chem. Commun. 71 (2015) 13634-13637. [24] K. Liang, C. Carbonell, M.J. Styles, R. Ricco, J. Cui, J.J. Richardson, D. Maspoch, F. Caruso and P. Falcaro, Biomimetic replication of microscopic metal-organic framework patterns using printed protein patterns, Adv. Mater. 45 (2015) 7293-7298. [25] F. Wang, J. Chen, H. Zhou, W. Li, Q. Zhang and C. Yu, Facile detection of latent fingerprints on various substrates based on perylene probe excimer emission, Anal. Methods. 3 (2014) 654-657. [26] G.S. Sodhi and J. Kaur, Powder method for detecting latent fingerprints: a review, Forensic. Sci. Int. 3 (2001) 172-176. [27] S. Oden and B.V. Hofsten, Detection of fingerprints by the ninhydrin reaction, Nature. 4401 (1954) 449-450. [28] R. Grigg, T. Mongkolaussavaratana, C. Anthony Pounds and S. Sivagnanam, 1,8-Diazafluorenone and related compounds. a new reagent for the detection of (α-amino acids and latent fingerprints.,
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Tetrahedron. Lett. 49 (1990) 7215-7218. [29] T.C. Fung, K. Grimwood, R. Shimmon, X. Spindler, P. Maynard, C. Lennard and C. Roux, Investigation of hydrogen cyanide generation from the cyanoacrylate fuming process used for latent fingermark detection, Forensic. Sci. Int. 1–3 (2011) 143-149. [30] M. Algarra, K. Radotić, A. Kalauzi, D. Mutavdžić, A. Savić, J. Jiménez-Jiménez, E. RodríguezCastellón, J.C.G.E. Silva and J.J. Guerrero-González, Fingerprint detection and using intercalated CdSe nanoparticles on non-porous surfaces, Anal. Chim. Acta. 812 (2014) 228-235.
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Biographies Dr. Xiaodong Jin received his Ph. D. degree in applied chemistry at Nanjing Tech University of China in 2016. He currently works at Jiangsu Police Institute. His current research interests are ions or molecular recognition, and the recognition of the latent fingerprints.
Ran Xin received his bachelor degree at National Police University of China, and he currently works at Center of Forensic Science and Technology, Bureau of Public Security for Jiangsu province. His current research interests is the recognition of the latent fingerprints.
Dr. Shifan Wang received his Ph. D. degree in applied chemistry at Nanjing Tech University of China in 2016. He currently works at Xuzhou Institute of Technology. His research interest focuses on the synthesis of fluorescent materials.
Dr. Wenzhu Yin received her MS degree of Chemistry in 2014 under the guidance of Prof. Hongjun Zhu at Nanjing tech University. She joined Prof. Huaqing Cao’s group at Tsinghua University as a PhD student. Her research interests are in the areas of materials chemistry and biosensor.
Tongxiang Xu is currently an associate professor in Jiangsu Police Institute. His current research interests focus on the trace detection, and the recognition of the latent fingerprints.
Yang Jiang is currently a junior student of forensic chemistry specialty in Jiangsu Police Institute of China.
Xuran Ji is currently a junior student of forensic chemistry specialty in Jiangsu Police Institute of China.
Luyang Chen is currently a junior student of forensic chemistry specialty in Jiangsu Police Institute of China.
Prof. Jingning Liu is currently a professor at Jiangsu Police Institute of China. His current research interest focus on the recognition of the latent fingerprints and drugs.
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Captions Fig. 1 X-ray crystal structure of probe FLA-1 Fig. 2 (a) Emission spectra of FLA-1 in CH3CN and CH3CN-water mixture with different fw. FLA-1 concentration: 0.25 mM, λex = 330 nm. (b) Plot of emission peak intensity against fw. Note: Spectral data were recorded 20 min after the addition of water to the CH3CN solvent. The fluorescent photographs of FLA-1 in CH3CN–water mixture solutions excited by a hand-held UV lamp with an excitation wavelength of 365 nm are shown (fw = 0–9, from left to right with an interval of 1). Fig. 3 Fluorescence images of sebaceous fingerprints on a a) coin, b) aluminium foil and c) glass slide developed by AIE of FLA-1 aggregates. The water fractions were 70, 60 and 70% for the three substrates. Fluorescence images of LFPs showing level 2 details including ridge termination (1, 4), bifurcation (2, 5) and lake (3, 6). All fluorescent images were excited with a 365 nm UV lamp. Fig. 4 Fluorescence images of sebaceous fingerprints on a) stainless steel sheet, b) pop-top can, c) beverage bottle, d) black color plastic, e) train ticket, f) paper cigarette case and g) envelop developed by AIE of FLA-1 aggregates. All fluorescent images were excited with a 365 nm UV lamp. Fig. 5 a) the Reference Fingerprint (abbreviated as R); b) the R fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as R1; c) the R1 fingerprint for analysis of correspondences; d) the fingerprint labeled as Scene Fingerprint (abbreviated as S) visualized by the probe FLA-1, irradiated by UV light taken from a glass; e) the S fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as S1; f) the S1 fingerprint for analysis of correspondences. (Note: the yellow and red ○ represent the minutia points of the fingerprint; the red ○ also represent the correspondences number of R1 and S1 fingerprint) Fig. 6 a) the Reference Fingerprint (abbreviated as R); b) the R fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as R1; c) the R1 fingerprint for analysis of correspondences; d) the fingerprint labeled as Scene Fingerprint (abbreviated as S) visualized by the probe FLA-1, irradiated by UV light taken from a aluminium foil; e) the S fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as S1; f) the S1 fingerprint for analysis of correspondences. (Note: the yellow and red ○ represent the minutia points of the fingerprint; the red ○ also represent the correspondences number of R1 and S1 fingerprint)
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Fig. 7 the Reference Fingerprint (abbreviated as R); b) the R fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as R1; c) the R1 fingerprint for analysis of correspondences; d) the fingerprint labeled as Scene Fingerprint (abbreviated as S) visualized by the probe FLA-1, irradiated by UV light taken from an coin; e) the S fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as S1; f) the S1 fingerprint for analysis of correspondences. (Note: the yellow and red ○ represent the minutia points of the fingerprint; the red ○ also represent the correspondences number of R1 and S1 fingerprint) Scheme 1. The routes of synthesis of compound FLA-1.
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S0925-4005(17)30079-5 http://dx.doi.org/doi:10.1016/j.snb.2017.01.080 SNB 21605
To appear in:
Sensors and Actuators B
Received date: Revised date: Accepted date:
13-10-2016 30-12-2016 10-1-2017
Please cite this article as: Xiaodong Jin, Ran Xin, Shifan Wang, Wenzhu Yin, Tongxiang Xu, Yang Jiang, Xuran Ji, Luyang Chen, Jingning Liu, A Tetraphenylethenebased Dye for Latent Fingerprint Analysis, Sensors and Actuators B: Chemical http://dx.doi.org/10.1016/j.snb.2017.01.080 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
A Tetraphenylethene-based Dye for Latent Fingerprint Analysis 1
Xiaodong Jin a, *, Ran Xinb, Shifan Wang c, Wenzhu Yin d, *, Tongxiang Xu a, Yang Jiang a, Xuran Ji a,
Luyang Chen a, and Jingning Liu a, b, *
a. Department of Criminal Science and Technology, Jiangsu Police Institute, Nanjing, Jiangsu, 210031, P. R. China. E-mail: [email protected] (Dr. Jin XD), Tel: +86-025-52881716; [email protected] (Prof. Liu JN) b. Center of Forensic Science and Technology, Bureau of Public Security for Jiangsu province, Nanjing, Jiangsu, 210024, P. R. China. c. School of Chemistry and Chemical Engineering, Xuzhou Institute of Technology, Xuzhou, 221111, P. R. China d. Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China. E-mail: [email protected] (Dr. Yin WZ)
*Corresponding authors： E-mail: [email protected] (Dr. Jin XD), Tel: +86-025-52881716; [email protected] (Dr. Yin WZ); [email protected] (Prof. Liu JN)
1
Highlight
A tetraphenylethene-based probe (FLA-1) was used to develop for recognition of the latent fingerprints on the surfaces of various substrates.
The approach do not need expensive or hazardous reagents, sophisticated instrument, and posttreatment procedures.
The resolution of the fingerprints visualized by the probe FLA-1 is enough to offer a positive match according to the information supplied from a police database.
Abstract A tetraphenylethene-based dye (FLA-1) was used to develop for enhancing the visualization of the latent fingerprints on the surfaces of various substrates. The resolution of the fingerprints visualized by the probe FLA-1 is enough to offer a positive match according to the information supplied from a police database. Experimental results confirm the accuracy of using the probe for LFPs detection.
Key words Fluorescence probe; Tetraphenylethene derivative; Aggregation Induced Emission; the latent fingerprints identification; Criminal science
Fluorescent probes are powerful tools which are important to analytical sensing, and the sensing sensitivity and accuracy of a probe is determined by the brightness and contrast of its fluorescence before and after analyte binding. [1-4] However, many conventional fluorophores are usually faced with a challenge that they will be quenched at high concentrations or in aggregate state. This leads us to what is called the concentration quenching or aggregation caused quenching (ACQ) phenomenon [5]. Evidently, it seems adverse to sense analytes including the latent fingerprints (LFPs), ions, and others. To our delight, the development of the fluorescent materials with high solid-state quantum yield in aggregated state or even in solid state which is known as the aggregation induced emission (AIE) effect of the dyes can solve the problem well. [6-10] So far, a variety of functional materials based on AIE fluorophores have been extensively reported, however, only a limited number of AIE dyes have been applied by visualizing the LFPs.[9-12] Fingerprints have been widely used in many fields, including forensic investigations and personal identification.[13] And, it was considered one of the most valuable physical evidence for identification at crime scenes.[14-17] Numerous efforts have been made in recent years to improve the existing techniques
2
for better visualization of the LFPs.[11, 13-14, 18-25] Powder dusting is the most commonly and portably used visualization technique for the LFPs.[26] However, it inevitably associated with serious problems in developing latent fingermarks, such as dust pollution, low sensitivity on wet surfaces and inevitable destruction of the fingerprint details when brushing magnetic or fluorescent powders on LFPs. Additionally, the commercial chemical reagents applied worldwide such as ninhydrin (NH)[27], 1,8diazafluoren-9-one (DFO)[28], often takes several minutes or hours, and cyanoacrylate (CA) unavoidably requires fuming for its deposition on the latter.[29] Therefore, it is necessary to develop some simple, cost-effective and reliable methods for the recognition of the LFPs with satisfactory sensitivity. In reality, it still remains a significant challenge. Satisfyingly, in 2012, Su’s research group first proposed a novel use of the aggregation induced emission (AIE) effect of tetraphenylethene (TPE) for the visualization enhancement of LFPs on wet non-porous surfaces.[9] The strategy presents several obvious advantages. Firstly, the overall process is performed in solutions and does not involve powder or fume treatment. Secondly, it can effective avoid the ACQ phenomenon to some extent of the conventionally employed luminescent dyes are absent. Thirdly, the sensing mechanism of visualizing the LFPs is reliant upon the preferential adhesion of TPE-derivate aggregates to the ridges by hydrophobic - hydrophobic interaction. In view of our interest in AIE-based fluorophores, we use the AIE strategy to recognize the LFPs. Recently, we have successfully developed a facile near infrared (NIR, 650-900 nm) probe NIR-LP based on ESIPT/AIE process for the visualization of the LFPS.[11] In this work, as a part of our on-going research on the visualization of the LFPs, we herein describe the design and synthesis of a simple fluorescent probe FLA-1 based on the TPE derivative for the recognition of LFPs (as shown in Scheme 1). As shown in Scheme 1, the fluorescent probe FLA-1 consists of two moieties: (i) TPE as the fluorescent core which is an archetypal AIE luminogens. (ii) The hydrophobic chain moiety was introduced into the TPE core to improve the hydrophobic property of TPE. Thus, we hope it can improve the hydrophobic - hydrophobic interaction between the TPE-derivate aggregates and the ridges of the LFPs. What’s more, we hope that the resolution of the fingerprints which would be visualized by the probe FLA-1 can be able to offer a positive match with those fingerprints present in databases to satisfy the police or other security agencies demand.
[Insert Scheme 1]
The probe FLA-1 was easily synthesized in good yield by the reaction of 4-(1,2,2triphenylvinyl)phenol with 4-vinylbenzyl chloride in the presence of K2CO3, and characterized by 1H 3
NMR (Fig. S1)and single crystal X-ray analysis (Fig. 1). Details of crystallographic data, selected bond distances, angles and structure refinement are summarized in Table S1.
[Insert Fig. 1] [Insert Fig. 2]
It is well known that TPE is a typical AIE fluorophore and most of the reported TPE-based dyes are AIE-active and emit blue or green light in their aggregated states due to the restricted intramolecular rotation (RIR) mechanism.[1, 5] To explore whether FLA-1 is AIE-active or not, the emission spectra of the dye in CH3CN and CH3CN–water mixture solutions were recorded (Fig. 2). It is clearly seen that the pure CH3CN solution of the dye FLA-1 were almost non-emissive and the fluorescence spectra are nearly parallel to the abscissa. However, the fluorescence intensities abruptly increased when the water volume fraction (fw) was greater 50%. It is probably the value of fw beyond 50% could induce the formation of FLA-1 aggregates, subsequently impeding the intramolecular rotations of the aromatic rotors of FLA-1. Thus, it endows the aggregates with intense emission.
[Insert Fig. 3]
Due to the excellent optical and AIE properties of the probe FLA-1, we intended to explore the application of the probe FLA-1 for potential LFPs imaging. The sebum-rich fingerprint development procedure is fairly simple. Sebaceous latent fingerprints were obtained from volunteers by gently rubbing their fingers over the forehead or nose and then pressing them on different substrates (including aluminium foils, coins and glass slides) to leave fingermarks that contain sebaceous materials (sebum). The fingerprints were typically developed by FLA-1 as follows. The substrate was swayed for an appropriate period of time (20 min) in the CH3CN-water mixtures of FLA-1 with different amounts of water, then gently rinsed with water twice or thrice. This process causes the initially invisible latent fingerprint to become blue-colored and visible to the naked eye (Fig. 3). Because the probe FLA-1 is fluorescent, the well-resolved friction ridge patterns of the latent fingerprint can be observed using a fluorescence microscope (Fig. 3). As a consequence of the fact that a latent sebaceous fingerprint is abundant in fatty acids, favorable hydrophobic interactions between FLA-1 aggregates and lipid, thus immobilizing the FLA-1 on fingerprint ridge structures. In fact, the high quality of the fingerprint images
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obtained by using this technique enables visualization of second level bifurcation, termination, and lake structures which are critical for forensic identification of individuals. Our results show that a fresh latent fingerprint deposited on different substrate surfaces, such as coin (Fig. 3a), glass slide (Fig. 3b), and aluminium foil (Fig. 3c) could be clearly seen when excited with a 365 nm UV lamp, with ridges, furrows, and other details clearly visible.
[Insert Fig. 4]
Subsequently, we make further evaluate the capacity of the dye FLA-1 to visualize the LFPs in other substrate surface (e.g., stainless steel sheet, pop-top can, beverage bottle, black color plastic, train ticket, paper cigarette case and envelop). From the experimental results, we found that the LFPs in stainless steel sheet, pop-top can and beverage bottle could be visualized well, and it display poor resolution in black color plastic and train ticket. However, it seems invisible in cigarette case and envelop. It was probably that the hydrophobicity of the substrate surface will influence the imaging quality of the LFPs fluorescent images. The paper cigarette case and envelop are apparently the most hydrophilic substrate. These results indicate that probe FLA-1 readily interacts with sebum-rich LFPs, especially on smooth surfaces (e.g., coin (Fig. 3a), glass slide (Fig. 3b), aluminium foil (Fig. 3c), stainless steel sheet (Fig. 4a), pop-top can (Fig. 4b) and beverage bottle (Fig. 4c)).
[Insert Fig. 5] [Insert Fig. 6]
In real crime scenes, we are more likely to encounter a problem that whether the latent fingerprint at different objects were left behind by the same criminal suspect or not. Thus we further demonstrate the robustness of the probe FLA-1 for practical use. The procedure carried out in the examination of the different fingerprints was as follows: In order to continue our research on the visualization of the LFPs, we choose a fingerprint that has been successfully recognized by us using the other probe and published in our previous study[11] as a standard fingerprint (a red fluorescent enhancement fingerprint) which was labeled as Reference Fingerprint (abbreviated as R). Then, the R fingerprint was introduced in the
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database of the police and we would obtain a treated picture as a gray-scale image where the ridges appear as light lines, and the furrows are the dark areas between the ridges, showing the enhancement of the images which was labeled as R1. Additionally, the latent fingerprint was detected under UV light and displayed a blue fluorescent enhancement fingerprint which was labeled as Scene Fingerprint (abbreviated as S) in different Figures (Figs. 5-7). All these images (S fingerprints in different Figures) were dimensioned to be suitable for the correspondences. Moreover, the S fingerprint images should be also processed. Namely, the different fingerprints at different objects (e.g. glass, aluminium foil and coin) are used as template images should be processed. And, we labeled these treated image as S1 in all figures (Figs. 5-7). These fingerprints have been introduced in the fingerprint database to be compared in the database and to do the correspondences with R1 fingerprints. After treatments above, we obtain the minutia points of R1 and S1 fingerprints through the computer system, and we get the correspondence fingerprints images which were labeled as R2 and S2, respectively. Fig. 5(a) shows the dimensioned fingerprint treated by probe NIR-LP which has been published by our previous study as the standard fingerprint (R fingerprint). Fig. 5(d) shows the fluorescence enhancement fingerprint (S fingerprint) treated by FLA-1 and irradiated on the surface of a glass. The S2 fingerprint in Fig. 5(f) shows correspondences to the direct images of R2 fingerprint and it was found to have 17 correspondences that the images of R2 and S2 fingerprint have 17 red ○ by one-to-one correspondence.
[Insert Fig. 7]
Other examples of images in non-porous surfaces have been also done, including aluminium foils (Fig. 6) and coins (Fig. 7). As shown in Fig. 6, R2 and S2 fingerprint have different contrast ratios that a total of 42 matching-characteristics (42 red ○ can one-to-one correspondence) were found. The same procedure was carried out with fingerprints taken from a coin (Fig. 7), and applying this simple procedure, 37 correspondences were obtained. It should be noted that the amount of characteristics varies from one to another, and is usually between 8 and 16 matches.[30] These experimental results confirm the accuracy of using the probe for LFPs detection.
Conclusions In summary, we have successfully developed a tetraphenylethene-based dye (FLA-1), which was characterized by 1H NMR and X-ray and by fluorescence spectroscopies, for enhancing the visualization of latent fingerprints on the surfaces of various substrates. The approach is pretty simple and cost-
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effective, upon a single-step treatment and only involves some simple and portable devices. Moreover, the overall process is performed in solutions and does not involve powder or fume treatment. In addition, the resolution of the fingerprints visualized by the dye FLA-1 is enough to offer a positive match according to the information supplied from a police database. Experimental results illustrate the effectiveness of proposed methods. We envisage that the method could be used for various forensic applications. And, a further research work is ongoing that we are polymerizing probe FLA-1 with the relevant monomer to endow the dye some other property, such as sensing the TNT or TNP in LFPs.
Acknowledgements This work was sponsored by the Jiangsu Students’ Platform for Innovation and Entrepreneurship Training Program (No. 201610329022Y and 201610329005Z), the Research Program for Young Scholars of Jiangsu Police Institute (No. 2016SJYZQ02), the Science and Technology Research Program for the Bureau of Public Security of Jiangsu province (No. 2016KX026), and the Science and Technology of Public Security of Jiangsu Police Institute - the Key Construction Disciplines at the Provincial Level of Jiangsu Province during 13th Five-Year Plan (2016-2020).
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Biographies Dr. Xiaodong Jin received his Ph. D. degree in applied chemistry at Nanjing Tech University of China in 2016. He currently works at Jiangsu Police Institute. His current research interests are ions or molecular recognition, and the recognition of the latent fingerprints.
Ran Xin received his bachelor degree at National Police University of China, and he currently works at Center of Forensic Science and Technology, Bureau of Public Security for Jiangsu province. His current research interests is the recognition of the latent fingerprints.
Dr. Shifan Wang received his Ph. D. degree in applied chemistry at Nanjing Tech University of China in 2016. He currently works at Xuzhou Institute of Technology. His research interest focuses on the synthesis of fluorescent materials.
Dr. Wenzhu Yin received her MS degree of Chemistry in 2014 under the guidance of Prof. Hongjun Zhu at Nanjing tech University. She joined Prof. Huaqing Cao’s group at Tsinghua University as a PhD student. Her research interests are in the areas of materials chemistry and biosensor.
Tongxiang Xu is currently an associate professor in Jiangsu Police Institute. His current research interests focus on the trace detection, and the recognition of the latent fingerprints.
Yang Jiang is currently a junior student of forensic chemistry specialty in Jiangsu Police Institute of China.
Xuran Ji is currently a junior student of forensic chemistry specialty in Jiangsu Police Institute of China.
Luyang Chen is currently a junior student of forensic chemistry specialty in Jiangsu Police Institute of China.
Prof. Jingning Liu is currently a professor at Jiangsu Police Institute of China. His current research interest focus on the recognition of the latent fingerprints and drugs.
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Captions Fig. 1 X-ray crystal structure of probe FLA-1 Fig. 2 (a) Emission spectra of FLA-1 in CH3CN and CH3CN-water mixture with different fw. FLA-1 concentration: 0.25 mM, λex = 330 nm. (b) Plot of emission peak intensity against fw. Note: Spectral data were recorded 20 min after the addition of water to the CH3CN solvent. The fluorescent photographs of FLA-1 in CH3CN–water mixture solutions excited by a hand-held UV lamp with an excitation wavelength of 365 nm are shown (fw = 0–9, from left to right with an interval of 1). Fig. 3 Fluorescence images of sebaceous fingerprints on a a) coin, b) aluminium foil and c) glass slide developed by AIE of FLA-1 aggregates. The water fractions were 70, 60 and 70% for the three substrates. Fluorescence images of LFPs showing level 2 details including ridge termination (1, 4), bifurcation (2, 5) and lake (3, 6). All fluorescent images were excited with a 365 nm UV lamp. Fig. 4 Fluorescence images of sebaceous fingerprints on a) stainless steel sheet, b) pop-top can, c) beverage bottle, d) black color plastic, e) train ticket, f) paper cigarette case and g) envelop developed by AIE of FLA-1 aggregates. All fluorescent images were excited with a 365 nm UV lamp. Fig. 5 a) the Reference Fingerprint (abbreviated as R); b) the R fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as R1; c) the R1 fingerprint for analysis of correspondences; d) the fingerprint labeled as Scene Fingerprint (abbreviated as S) visualized by the probe FLA-1, irradiated by UV light taken from a glass; e) the S fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as S1; f) the S1 fingerprint for analysis of correspondences. (Note: the yellow and red ○ represent the minutia points of the fingerprint; the red ○ also represent the correspondences number of R1 and S1 fingerprint) Fig. 6 a) the Reference Fingerprint (abbreviated as R); b) the R fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as R1; c) the R1 fingerprint for analysis of correspondences; d) the fingerprint labeled as Scene Fingerprint (abbreviated as S) visualized by the probe FLA-1, irradiated by UV light taken from a aluminium foil; e) the S fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as S1; f) the S1 fingerprint for analysis of correspondences. (Note: the yellow and red ○ represent the minutia points of the fingerprint; the red ○ also represent the correspondences number of R1 and S1 fingerprint)
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Fig. 7 the Reference Fingerprint (abbreviated as R); b) the R fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as R1; c) the R1 fingerprint for analysis of correspondences; d) the fingerprint labeled as Scene Fingerprint (abbreviated as S) visualized by the probe FLA-1, irradiated by UV light taken from an coin; e) the S fingerprint was introduced in the database of the police for contrast enhancement and the image was labeled as S1; f) the S1 fingerprint for analysis of correspondences. (Note: the yellow and red ○ represent the minutia points of the fingerprint; the red ○ also represent the correspondences number of R1 and S1 fingerprint) Scheme 1. The routes of synthesis of compound FLA-1.
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