Skip to main content
NCBI home page
NIHPA Author Manuscripts logoLink to NIHPA Author Manuscripts
. Author manuscript; available in PMC: 2016 Nov 2.
Published in final edited form as: Nano Res. 2015 Mar 28;8(6):1800–1810. doi: 10.1007/s12274-014-0686-6

NIR-induced highly sensitive detection of latent finger-marks by NaYF4:Yb,Er upconversion nanoparticles in a dry powder state

Meng Wang 1,2,✉, Ming Li 1,2, Mingying Yang 3,✉, Xiaomei Zhang 1,2, Aoyang Yu 1,2, Ye Zhu 4, Penghe Qiu 4, Chuanbin Mao 4,✉
PMCID: PMC5091657  NIHMSID: NIHMS797020  PMID: 27818741

Abstract

The most commonly found fingermarks at crime scenes are latent and, thus, an efficient method for detecting latent fingermarks is very important. However, traditional developing techniques have drawbacks such as low detection sensitivity, high background interference, complicated operation, and high toxicity. To tackle this challenge, we employed fluorescent NaYF4:Yb,Er upconversion nanoparticles (UCNPs), which can fluoresce visible light when excited by 980 nm human-safe near-infrared light, to stain the latent fingermarks on various substrate surfaces. The UCNPs were successfully used as a novel fluorescent label for the detection of latent fingermarks with high sensitivity, low background, high efficiency, and low toxicity on various substrates including non-infiltrating materials (glass, marble, aluminum alloy sheets, stainless steel sheets, aluminum foils, and plastic cards), semi-infiltrating materials (floor leathers, ceramic tiles, wood floor, and painted wood), and infiltrating materials such as various types of papers. This work shows that UCNPs are a versatile fluorescent label for the facile detection of fingermarks on virtually any material, enabling their practical applications in forensic sciences.

Keywords: upconversion, nanoparticles, fingermark, development

1 Introduction

A fingermark is one of the most powerful traces that can be exploited as evidence for the identity of individuals since it represents the unique ridge skin pattern of an individual’s finger. The most commonly found fingermarks at crime scenes are typically latent. Namely, they are normally invisible or less visible to investigators and can only be visualized by certain developing techniques. To date, many fingermark developing techniques have been studied and used by fingerprint scientists, including powder (metallic, magnetic, or fluorescent powder) dusting [1], ninhydrin spraying [2], iodine fuming, cyanoacrylate fuming [3–5], and silver nitrate soaking. However, these traditional techniques are still associated with serious problems in developing latent fingermarks, such as low detection sensitivity, high background interference, complicated operation, and high toxicity. Therefore, there is a pressing need to create a simple method in developing latent fingermarks with high sensitivity, low background, high efficiency, and low toxicity, which is the long-term goal for forensic scientists.

Recently, new techniques such as electrochemiluminescence and nanotechnology have been applied toward the enhanced development of latent fingermarks [6–11]. In particular, the use of fluorescent nanoparticles (NPs), such as quantum dots (QDs), for the development of latent fingermarks has attracted significant research interest in forensic science [12–18]; this is because of their unique physical and chemical properties such as small particle size, large surface area, good photochemical stability, and high fluorescent intensity. The integration of QDs in latent fingermark development provides a variety of advantages including increased sensitivity, enhanced contrast, and improved selectivity [19–26]. When excited by ultraviolet (UV) radiation, QDs can emit strong visible fluorescence to enhance fingermark contrast. However, UV light is needed to excite QDs and other fluorescent NPs, resulting in many drawbacks including the following: high background interference owing to the significant autofluorescence from the substrates, photo damage to the skin and eyes of the operators, and the possibility of severe irradiation-induced damage of DNA in fingermark residue, resulting in the subsequent DNA analysis failing. Furthermore, increasing concerns on the inherent toxicity of QDs limit their long-term use [27–29]. Therefore, a novel type of fluorescent NPs with high sensitivity, low background, high efficiency, and low toxicity is needed for the development of latent fingermarks in the field of forensic chemistry.

Fluorescent upconversion (UC) NPs (UCNPs) can convert a longer wavelength radiation (e.g., near-infrared (NIR) light) into a shorter wavelength emission (e.g., visible light) via a two-photon or multi-photon mechanism [30, 31]. They can emit strong visible fluorescence, suggesting they can reach a high sensitivity and a high contrast in latent fingermark development through fluorescence imaging [32–36]. The excitation of UCNPs often requires NIR radiation (e.g., 980 nm); this low energy radiation cannot cause autofluorescence from the substrates, and thus background interference can be avoided in the detection of fingermarks [36]. Compared with UV radiation, lower-energy NIR radiation is non-toxic and often desired in biomedical imaging, because it is less harmful to the skin and eyes of the operators as well as the DNA in fingermark residue. In addition, UCNPs have other prominent advantages, such as a narrow emission peak, large Stokes shifts, good chemical/physical stability, and low toxicity [37–40]. Therefore, UCNPs are promising alternatives to traditional fluorescent NPs, such as QDs, for latent fingermark development. Recently, it was reported that commercially available NaYF4:Yb,Er UC fluorescent particles could be used for the development of latent fingermarks [41]. However, the commercial particles used were not well dispersed and uniform in shape, having a large size range from ~0.2 to 2 μm. Such large particles with nonuniform shapes could interfere with the affinity between the particles and the fingermark; even detailed features of the fingermarks, such as sweat pores, could be covered by the larger particles, leading to decreased detection sensitivity.

Hence, for the first time we report the use of nano-sized NaY0.78F4:Yb0.20,Er0.02 dry powder as a novel UC fluorescent label for completely developing whole latent fingermarks. We successfully used UCNPs to clearly image latent fingermarks on various smooth substrates, including glass, ceramic tiles, floor leathers, marble of different surface textures, metallic materials (aluminum alloy sheets, stainless steel sheets, and aluminum foils), polymeric materials (plastic cards), wood materials (wood floor and painted wood), and various papers (train tickets, printing papers, magazine covers, and note papers). Owing to the use of UCNP powder to develop fingermarks, the friction ridge details of fingermarks on various smooth substrates could be clearly defined without background interference or color distraction under the excitation of human-safe NIR light, resulting in good contrast for enhanced fingermark development.

2 Experimental

2.1 Materials

The rare earth oxides used in this work, including yttrium oxide (Y2O3), ytterbium oxide (Yb2O3), and erbium oxide (Er2O3), were all of 99.99% purity. Sodium fluoride (NaF), stearic acid (C17H35COOH), oleic acid (C17H33COOH), sodium hydroxide (NaOH), and nitric acid (HNO3) were of analytical grade. Triple-distilled water was used throughout the experiments.

2.2 Characterization

The size and morphology of as-prepared UCNPs were observed with a transmission electron microscope (TEM) using an accelerating voltage 200 kV. X-ray diffraction (XRD) measurements were performed on an X’Pert Pro diffractometer (PANalytical Co., Holland) at a scanning rate of 8°/min in the 2θ range of 10 to 80°, with graphite monochromatized Cu-Kα radiation (λ = 0.15406 nm). UC fluorescent spectra of the dried NP powder were measured on an LS-55 fluorescence spectrophotometer (Perkin Elmer Co., USA) attached with an external 980 nm laser (Beijing Hi-Tech Optoelectronic Co., China) instead of an internal excitation source. The UCNP labeled fingermarks were irradiated by a 980 nm laser (Suzhou Xiaosong Technology Development Co., Ltd. China) equipped with a beam expander. The power of the 980 nm laser was 15 W and the power density was 1.67 W/cm2. The fingermark images were photographed in situ by using a Nikon D800 digital camera equipped with an AF-S Nikkor 24–70 mm f/2.8G ED lens.

2.3 Synthesis of NaYF4:Yb,Er upconversion nano-particles

We followed our reported oleic acid-based solvothermal method with a minor modification [42, 43]. In this synthesis, rare earth stearate was used as a precursor. A mixture of 0.8807 g of Y2O3, 0.3941 g of Yb2O3, and 0.0383 g of Er2O3 was dissolved in nitric acid by heating to form the rare earth nitrates; the nitrate powder was obtained after solvent evaporation. The as-prepared powder and 8.5344 g of stearic acid were dissolved in 150 ml ethanol in a three-neck flask with vigorous stirring at 50 °C. Subsequently, the temperature was elevated to 78 °C. Then another solution containing 1.1900 g of NaOH and 20 ml of ethanol was added dropwise into the flask. The resulting mixture was refluxed at 78 °C for another 40 min. Precipitates from the reaction mixture were filtrated under decompression and washed with ethanol thrice. The precursor powder was obtained after the precipitates were dried at 60 °C for 12 h. Subsequently, 100 ml of water, 150 ml of ethanol, and 50 ml of oleic acid were mixed together under stirring to form a homogeneous solution, to which 9.5772 g of precursor powder and 2.0995 g of NaF were added. The resulting mixture was stirred under sonication for 15 min, transferred into a 500 ml autoclave, sealed, and then solvothermally treated at 180 °C for 24 h. After the autoclave was naturally cooled to room temperature, the UCNPs were deposited at the bottom of the vessel, and a mixture of chloroform and ethanol (1:6, v/v) was used to collect the precipitates. The UCNPs were purified by centrifugation, washed with a mixture of water and ethanol (1:2, v/v) three times, and dried at 60 °C for 12 h. NaYF4:Yb,Er UCNPs were thus formed.

2.4 Detection of latent fingermarks using NaYF4:Yb,Er upconversion nanoparticles

All the fingermarks were collected from the same donor. Firstly, hands were washed thoroughly with soap. The fingers were then gently wiped across the forehead. Finally, the fingers were pressed on the surfaces of different substrates at room temperature to obtain latent fingermarks. To develop the resultant latent fingermarks, the dry NaYF4:Yb,Er UCNP powder was carefully applied to the surface of the substrates with a light brushing action. The excess powder was removed by dusting the substrate surfaces with a gentle, smooth motion until a fingermark image was developed. The fingermark images were photographed in situ with a Nikon D800 digital camera equipped with an AF-S Nikkor 24–70 mm f/2.8G ED lens and a 980 nm laser light for exciting the NaYF4:Yb,Er UCNPs.

3 Results and discussion

3.1 Characterization of NaYF4:Yb,Er upconversion nanoparticles

Synthesis methods for high-quality NaYF4:Yb,Er UCNPs have been well established and widely reported, including the thermal decomposition method [44–46], hydrothermal method, and solvothermal method [47–49]. Here, we used an oleic acid-based solvothermal method to chemically synthesize NaYF4:Yb,Er UCNPs. The as-prepared NaYF4:Yb,Er UCNPs were then characterized by TEM, XRD, and fluorescence spectroscopy. It is known that there are two polymorphs in NaREF4 (RE = rare earth) at ambient pressure: a cubic α-phase (metastable high-temperature phase) and a hexagonal β-phase (thermodynamically stable low-temperature phase). β-NaREF4 can be obtained from α-NaREF4 via a cubic-to-hexagonal phase transition process [50, 51]. The β-NaREF4 phase is desired as it shows a strong UC fluorescence in comparison to α-NaREF4. The TEM image (Fig. 1(a)) as well as XRD patterns (Fig. 1(b)) collectively confirm that the obtained NaYF4:Yb,Er UCNPs are of pure β-phase with a regular spherical shape. The histogram of the particle diameter (Fig. S1 in the Electronic Supplementary Material (ESM)) reveals that the NaYF4:Yb,Er UCNPs are 62–89 nm in diameter, with an average value of 74.2 nm. The resultant NaYF4:Yb,Er UCNPs emitted strong green fluorescence under 980 nm irradiation (Figs. 1(c) and 1(d)). Such strong NIR-induced green fluorescence from synthetic β-phase NaYF4:Yb,Er UCNPs inspired us to use them for developing latent fingermarks on non-infiltrating materials (including glass, marble, aluminum alloy sheets, stainless steel sheets, aluminum foils, and plastic cards), semi-infiltrating materials (including floor leathers, ceramic tiles, wood floor, and painted wood), and infiltrating materials such as various types of paper.

Figure 1.

Figure 1

Open in a new tab

Characterization of NaYF4:Yb,Er UCNPs synthesized at 180 °C for 24 h and their use in developing fingermarks along with other traditional developing materials. (a) TEM image, (b) powder XRD pattern, (c) photograph of the UCNP powder excited with a 980 nm laser, and (d) UC fluorescence spectrum under 980 nm excitation.

3.2 Mechanism of latent fingermark development by using NaYF4:Yb,Er upconversion nanoparticles

The powder development method is essentially a physical phenomenon, which relies on the adherence of powder particles to the moisture (such as sweat) and oily components (such as grease and oil) in the fingermark residue [1, 52]. Thus, it is expected that this attraction decreases with the evaporation of the fingermark residue. Scheme 1 illustrates the general principle of latent fingermark development by using NaYF4:Yb,Er UCNPs. NaYF4:Yb,Er UCNP powder was first deposited onto the fingermarks. The sweat and grease in the fingermark residue drove the quick physical adsorption of the UCNPs onto the ridges produced on the substrate when the fingermarks were printed. 980 nm NIR light was then used to irradiate the fingermarks, exciting the UCNPs to emit green light and consequently revealing the fingermark image.

Scheme 1.

Scheme 1

Open in a new tab

Illustration of the development of latent fingermarks using a UCNP powder dusting process. A fingermark was printed on a substrate such as glass, marble, alumina alloys, wood floor, or ceramic tiles. Then, NaYF4:Yb,Er UCNP powder was deposited onto the substrate to stain the fingermark. A human-safe NIR light was then used to irradiate the fingermark, leading to the excitation of UCNPs to emit green light and consequently revealing the fingermark with high sensitivity and contrast.

3.3 Latent fingermark development by using NaYF4:Yb,Er UCNPs

To determine the effectiveness of NaYF4:Yb,Er UCNPs as fluorescence labels for the development of latent fingermarks on marble, traditionally used staining materials including magnetic iron oxide power, TiO2 powder, and commercial fluorescent powder were used as a control (Figs. 2(a)–2(c)). It was found that the magnetic powder and TiO2 powder could not completely develop the latent fingermarks on marble (Figs. 2(a) and 2(b)). When the UV light was applied to the fingermarks stained by the traditional fluorescent powder, the friction ridges of the fingermarks could not be clearly resolved (Fig. 2(c)). However, when 980 nm NIR light was used to irradiate the fingermarks stained by UCNPs, the friction ridges of the fingermarks were clearly revealed with sharp edges (Fig. 2(d)), showing that our NaYF4:Yb,Er UCNPs could be used as an effective powder for the development of latent fingermarks due to their enhanced strong green luminescence.

Figure 2.

Figure 2

Open in a new tab

Latent fingermarks on the surface of marble stained by (a) magnetic iron oxide powder, (b) TiO2 powder, (c) commercially available yellow fluorescent powder (Lot #D012, made by Beijing Fenge Science Ltd.), and (d) NaYF4:Yb,Er UCNPs. The bottles in (a)–(d) show the appearance of those materials used to stain the fingermarks. The scale bar corresponds to 8.0 mm.

To determine the sensitivity of the UCNPs-based fingermark detection, a series of control experiments using traditional powders as well as micron-sized NaYF4:Yb,Er UC powders were performed. The synthesis method used to obtain the micron-sized NaYF4:Yb,Er UC powder is given in the ESM, and the scanning electron micrograph is shown in Fig. S2 in the ESM. As shown in Fig. 3, detailed features of the fingermarks, such as sweat pores, can be clearly observed with NaYF4:Yb,Er UCNPs (Figs. 3(a) and 3(b)), due to their small particle size, which is almost impossible to achieve with the micron-sized NaYF4:Yb,Er UC powders (Figs. 3(c) and 3(d)). In the case of the fingermarks developed by traditional powders, including bronze powder, magnetic iron oxide powder, and yellow fluorescent powder, detailed features, such as sweat pores could not be clearly observed (Fig. S3 in the ESM). These results clearly show that using UCNPs for fingermark detection can reveal more detailed features, leading to the high sensitivity of the developing method.

Figure 3.

Figure 3

Open in a new tab

Magnified images of latent fingermarks stained by NaYF4:Yb,Er UCNPs ((a), (b)) and micron-sized NaYF4:Yb,Er UC powders ((c), (d)), and then imaged on the surface of glass: ((a), (c)) Images in bright field without 980 nm NIR excitation and ((b), (d)) UC fluorescent images formed owing to the excitation of UCNPs by a 980 nm NIR radiation. The scale bar corresponds to 2.5 mm.

In order to demonstrate the practicality of the UCNPs-based fingermark detection method in forensic sciences, we conducted the fingermark development experiments after the fingermarks had been aged for different periods of time. As shown in Fig. 4, the detection sensitivity decreased gradually with prolonged aging of the fingermarks, due to the gradual evaporation of the fingermark. However, latent fingermarks aged for up to 1 year could still be developed with clear ridges, indicating that the sensitivity in the UCNP-based method was high enough for aged fingermark development.

Figure 4.

Figure 4

Open in a new tab

Latent fingermarks aged on the surface of glass for various periods of time, stained by NaYF4:Yb,Er UCNPs, and finally detected by 980 nm light irradiation: (a) 1 day, (b) 3 days, (c) 1 week, (d) 1 month, (e) 6 months, and (f) 1 year. The scale bar corresponds to 5.0 mm.

To determine the background interference of the UCNP-based fingermark detection, various types of marble with complex surface patterns were chosen as a substrate, where fingermarks were printed, stained by UCNP powder, and then detected by NIR-induced green light emission from the UCNPs (Fig. 5). As shown in Figs. 5(b’)–5(f’), the well-defined friction ridges on the various types of marble with different textures could be clearly defined without background interference or color disruption after NIR light irradiation on the fingermarks, resulting in excellent contrast for enhanced fingermark development. However, before NIR light irradiation, the fingermarks on the corresponding surfaces of the same marble were latent and almost invisible to the naked eye (Figs. 5(b)–5(f)). Similarly, excellent fingermark images were detected on other non-infiltrating materials, such as glass, after NIR irradiation (Fig. 5(a’)) in contrast to the hardly seen images before NIR irradiation (Fig. 5(a)). These results clearly show that the UCNPs, used for fingermark detection, can avoid the background interference, leading to the high sensitivity of the developing method.

Figure 5.

Figure 5

Open in a new tab

Latent fingermarks stained by NaYF4:Yb,Er UCNPs and imaged on the surface of glass ((a), (a’)) and various types of marble with different textures ((b)–(f), (b’)–(f’)): ((a)–(f)) are images in bright field without 980 nm NIR excitation and ((a’)–(f’)) are UC fluorescent images formed owing to the excitation of UCNPs by a 980 nm NIR radiation. The scale bar corresponds to 5.0 mm.

In addition to the detection of the fingermarks on the surface of glass and marble, a series of development experiments using NaYF4:Yb,Er UCNPs were also carried out on the surfaces of a variety of other objects, including aluminum alloy sheets, stainless steel sheets, aluminum foils, plastic cards, floor leather, ceramic tiles, wood floor, and pained wood. Well-defined friction ridges of the fingermarks could be clearly observed on all of the samples (Fig. 6) without background interference, demonstrating that our developing method is versatile and can be applied to detect fingermarks on virtually all smooth objects.

Figure 6.

Figure 6

Open in a new tab

Latent fingermarks stained by NaYF4:Yb,Er UCNPs and detected on the surface of various substrates after 980 nm light irradiation: (a) aluminum alloy sheets, (b) stainless steel sheets, (c) aluminum foils, (d)–(e) plastic cards, (f) floor leathers, (g) ceramic tiles, (h) wood floor, and (i) painted wood. The scale bar corresponds to 5.0 mm.

We then proceeded with the evaluation of the use of UCNPs in the detection of fingermarks printed on infiltrating materials such as various types of paper, including train tickets, printing papers, magazine covers, and note papers (Fig. 7). Surprisingly, the fingermarks on these materials could also be clearly detected, similar to the fingermark development results on the non- or semi-infiltrating material (Figs. 5 and 6).

Figure 7.

Figure 7

Open in a new tab

Latent fingermarks on the surface of various paper substrates, which were stained by NaYF4:Yb,Er UCNPs and then detected by NIR-induced fluorescence imaging: (a) train ticket, (b) printing paper, (c) magazine cover, and (d) note paper. The scale bar corresponds to 5.0 mm.

As shown by the aforementioned results, we have successfully employed NaYF4:Yb,Er UCNPs to detect fingermarks on a variety of different substrates. Our results show that dry NaYF4:Yb,Er UCNP powder can image whole fingermarks with high efficiency (because the whole procedure was fast and could be finished in approximately 30 s for trained investigators), high sensitivity (because background interference can be avoided owing to the use of NIR light as an excitation source, and sweat pores can be observed owing to the small particle size), and low toxicity (because NaYF4:Yb,Er UCNPs have proven to be biocompatible and NIR light is human-safe). Namely, the whole procedure is facile and rapid; an investigator only needs to apply pre-synthesized NaYF4:Yb,Er UCNP powder onto the fingermarks, immediately followed by imaging the fingermarks under a fluorescence microscope with a 980 nm NIR light source. Moreover, NaYF4:Yb,Er UCNPs can be stored for a long duration without losing their UC fluorescence capability, allowing investigators to use pre-synthesized UCNPs. Fingermarks also contain biomolecules such as DNA, which serves as an additional marker for identifying an individual. NIR light will not damage DNA, unlike the UV light used to excite traditional fluorescent NPs, such as QDs. Thus, the DNA collected from fingermarks after fingermark development could still be analyzed and used for verifying the identity of individuals. Therefore, the use of NIR light for triggering the visible light emission from UCNPs-stained fingermarks makes dry UCNP powders more attractive for forensic scientists.

4 Conclusions

In summary, NaY0.78F4:Yb0.20,Er0.02 UCNPs with strong UC fluorescence induced by 980 nm NIR light, synthesized via a solvothermal approach, were successfully used as a novel fluorescent label for the development of latent fingermarks on various substrates, including glass, ceramic tiles, floor leathers, marble of different surface textures, metallic materials (aluminum alloy sheets, stainless steel sheets, and aluminum foils), polymeric materials (plastic cards), wood materials (wood floor and painted wood), and various papers (train tickets, printing papers, magazine covers, and note papers). The development procedure is facile and exhibits outstanding performance with high sensitivity, low background, high efficiency, and low toxicity. The work opens up a new avenue in the use of UCNPs in developing whole latent fingermarks in forensic sciences.

Supplementary Material

SI

Acknowledgments

This work is supported by the National Natural Science Foundation of China (No. 21205139), the Application and Innovation Project of Chinese Ministry of Public Security (No. 2012YYCXXJXY127), and the Program for Liaoning Excellent Talents in University (No. LJQ2014130). MYY is thankful for the grant support from the National Natural Science Foundation of China (Nos. 20804037 and 21172194) and National High Technology Research and Development Program 863 (No. 2013AA102507). YZ, PHQ and CBM would like to thank the financial support from National Institutes of Health (No. EB015190), National Natural Science Foundation (No. CMMI-1234957 and DMR-0847758), Department of Defense Peer Reviewed Medical Research Program (No. W81XWH-12-1-0384), Oklahoma Center for the Advancement of Science and Technology (No. HR14-160) and Oklahoma Center for Adult Stem Cell Research (No. 434003).

Footnotes

Electronic Supplementary Material: This material is available in the online version of this article at http://dx.doi.org/10.1007/s12274-014-0686-6.

References

  • 1.Sodhi GS, Kaur J. Powder method for detecting latent fingerprints: A review. Forensic Sci Int. 2001;120:172–176. doi: 10.1016/s0379-0738(00)00465-5. [DOI] [PubMed] [Google Scholar]
  • 2.Oden S, Von Hofsten B. Detection of fingerprints by the ninhydrin reaction. Nature. 1954;173:449–450. doi: 10.1038/173449a0. [DOI] [PubMed] [Google Scholar]
  • 3.Tahtouh M, Kalman JR, Reedy BJ. Synthesis and characterization of four alkyl 2-Cyanoacrylate monomers and their precursors for use in latent fingerprint detection. J Polym Sci Pol Chem. 2011;49:257–277. [Google Scholar]
  • 4.Fung TC, Grimwood K, Shimmon R, Spindler X, Maynard P, Lennard C, Roux C. Investigation of hydrogen cyanide generation from the cyanoacrylate fuming process used for latent fingermark detection. Forensic Sci Int. 2011;212:143–149. doi: 10.1016/j.forsciint.2011.06.004. [DOI] [PubMed] [Google Scholar]
  • 5.Kendall FG, Rehn BWJ. Rapid method of super glue fuming application for the development of latent fingerprints. Forensic Sci. 1983;28:777–780. [Google Scholar]
  • 6.Xu LR, Li Y, Wu SZ, Liu XH, Su B. Imaging latent fingerprints by electrochemiluminescence. Angew Chem Int Ed. 2012;51:8068–8072. doi: 10.1002/anie.201203815. [DOI] [PubMed] [Google Scholar]
  • 7.Li Y, Xu LR, Su B. Aggregation induced emission for the recognition of latent fingerprints. Chem Commun. 2012;48:4109–4111. doi: 10.1039/c2cc30553d. [DOI] [PubMed] [Google Scholar]
  • 8.Li Y, Xu LR, He YY, Su B. Enhancing the visualization of latent fingerprints by electrochemiluminescence of rubrene. Electrochem Commun. 2013;33:92–95. [Google Scholar]
  • 9.Li K, Qin WW, Li F, Zhao XC, Jiang BW, Wang K, Deng SH, Fan CH, Li D. Nanoplasmonic imaging of latent fingerprints and identification of cocaine. Angew Chem Int Ed. 2013;52:11542–11545. doi: 10.1002/anie.201305980. [DOI] [PubMed] [Google Scholar]
  • 10.Xu LR, Zhou ZY, Zhang CZ, He YY, Su B. Electrochemiluminescence imaging of latent fingermarks through the immunodetection of secretions in human perspiration. Chem Commun. 2014;50:9097–9100. doi: 10.1039/c4cc03466j. [DOI] [PubMed] [Google Scholar]
  • 11.Tan J, Xu LR, Li T, Su B, Wu JM. Image-contrast technology based on the electrochemiluminescence of porous silicon and its application in fingerprint visualization. Angew Chem Int Ed. 2014;53:9822–9826. doi: 10.1002/anie.201404948. [DOI] [PubMed] [Google Scholar]
  • 12.Choi MJ, McDonagh AM, Maynard P, Roux C. Metal-containing nanoparticles and nano-structured particles in fingermark detection. Forensic Sci Int. 2008;179:87–97. doi: 10.1016/j.forsciint.2008.04.027. [DOI] [PubMed] [Google Scholar]
  • 13.Becue A, Scoundrianos A, Champod C, Margot P. Fingermark detection based on the in situ growth of luminescent nanoparticles—Towards a new generation of multimetal deposition. Forensic Sci Int. 2008;179:39–43. doi: 10.1016/j.forsciint.2008.04.008. [DOI] [PubMed] [Google Scholar]
  • 14.Hussain I, Hussain SZ, Habib-ur-Rehman, Ihsan A, Rehman A, Khalid ZM, Brust M, Cooper AI. In situ growth of gold nanoparticles on latent fingerprints-from forensic applications to inkjet printed nanoparticle patterns. Nanoscale. 2010;2:2575–2578. doi: 10.1039/c0nr00593b. [DOI] [PubMed] [Google Scholar]
  • 15.Becue A, Champod C, Margot P. Use of gold nanoparticles as molecular intermediates for the detection of fingermarks. Forensic Sci Int. 2007;168:169–176. doi: 10.1016/j.forsciint.2006.07.014. [DOI] [PubMed] [Google Scholar]
  • 16.Jones BJ, Reynolds AJ, Richardson M, Sears VG. Nano-scale composition of commercial white powders for development of latent fingerprints on adhesives. Sci Justice. 2010;50:150–155. doi: 10.1016/j.scijus.2009.08.001. [DOI] [PubMed] [Google Scholar]
  • 17.Sametband M, Shweky I, Banin U, Mandler D, Almog J. Application of nanoparticles for the enhancement of latent fingerprints. Chem Commun. 2007:1142–1144. doi: 10.1039/b618966k. [DOI] [PubMed] [Google Scholar]
  • 18.Theaker BJ, Hudson KE, Rowell FJ. Doped hydrophobic silica nano- and micro-particles as novel agents for developing latent fingerprints. Forensic Sci Int. 2008;174:26–34. doi: 10.1016/j.forsciint.2007.02.030. [DOI] [PubMed] [Google Scholar]
  • 19.Dilag J, Kobus H, Ellis AV. Cadmium sulfide quantum dot/chitosan nanocomposites for latent fingermark detection. Forensic Sci Int. 2009;187:97–102. doi: 10.1016/j.forsciint.2009.03.006. [DOI] [PubMed] [Google Scholar]
  • 20.Gao F, Lv CF, Han JX, Li XY, Wang Q, Zhang J, Chen C, Li Q, Sun XF, Zheng JC, et al. CdTe-montmorillonite nanocomposites: Control synthesis, UV radiation-dependent photoluminescence, and enhanced latent fingerprint detection. J Phys Chem C. 2011;115:21574–21583. [Google Scholar]
  • 21.Gao F, Han J, Lv C, Wang Q, Zhang J, Li Q, Bao L, Li X. Application of core–shell-structured CdTe@SiO2 quantum dots synthesized via a facile solution method for improving latent fingerprint detection. J Nanopart Res. 2012;14:1–11. [Google Scholar]
  • 22.Jin YJ, Luo YJ, Li GP, Li J, Wang YF, Yang RQ, Lu WT. Application of photoluminescent CdS/PAMAM nanocomposites in fingerprint detection. Forensic Sci Int. 2008;179:34–38. doi: 10.1016/j.forsciint.2008.04.010. [DOI] [PubMed] [Google Scholar]
  • 23.Wang YF, Yang RQ, Wang YJ, Shi ZX, Liu JJ. Application of CdSe nanoparticle suspension for developing latent fingermarks on the sticky side of adhesives. Forensic Sci Int. 2009;185:96–99. doi: 10.1016/j.forsciint.2008.12.021. [DOI] [PubMed] [Google Scholar]
  • 24.Liu JJ, Shi ZX, Yu YC, Yang RQ, Zuo SL. Water-soluble multicolored fluorescent CdTe quantum dots: Synthesis and application for fingerprint developing. J Colloid Interf Sci. 2010;342:278–282. doi: 10.1016/j.jcis.2009.10.061. [DOI] [PubMed] [Google Scholar]
  • 25.Gao F, Han JX, Zhang J, Li Q, Sun XF, Zheng JC, Bao LR, Li X, Liu ZL. The synthesis of newly modified CdTe quantum dots and their application for improvement of latent fingerprint detection. Nanotechnology. 2011;22:075705. doi: 10.1088/0957-4484/22/7/075705. [DOI] [PubMed] [Google Scholar]
  • 26.Becue A, Moret S, Champod C, Margot P. Use of quantum dots in aqueous solution to detect blood fingermarks on non-porous surfaces. Forensic Sci Int. 2009;191:36–41. doi: 10.1016/j.forsciint.2009.06.005. [DOI] [PubMed] [Google Scholar]
  • 27.Chang E, Thekkek N, Yu WW, Colvin VL, Drezek R. Evaluation of quantum dot cytotoxicity based on intracellular uptake. Small. 2006;2:1412–1417. doi: 10.1002/smll.200600218. [DOI] [PubMed] [Google Scholar]
  • 28.Byrne SJ, Williams Y, Davies A, Corr SA, Rakovich A, Gunko YK, Rakovich YP, Donegan JF, Volkov Y. “Jelly dots”: Synthesis and cytotoxicity studies of CdTe quantum dot-gelatin nanocomposites. Small. 2007;3:1152–1156. doi: 10.1002/smll.200700090. [DOI] [PubMed] [Google Scholar]
  • 29.Tsay JM, Michalet X. New light on quantum dot cytotoxicity. Chem Biol. 2005;12:1159–1161. doi: 10.1016/j.chembiol.2005.11.002. [DOI] [PubMed] [Google Scholar]
  • 30.Auzel F. Upconversion and anti-stokes processes with f and d ions in solids. Chem Rev. 2004;104:139–173. doi: 10.1021/cr020357g. [DOI] [PubMed] [Google Scholar]
  • 31.Schafer H, Haase M. Upconverting nanoparticles. Angew Chem Int Ed. 2011;50:5808–5829. doi: 10.1002/anie.201005159. [DOI] [PubMed] [Google Scholar]
  • 32.Wang LY, Zhang Y, Zhu YY. One-pot synthesis and strong near-infrared upconversion luminescence of poly(acrylic acid)-functionalized YF3:Yb3+/Er3+ nanocrystals. Nano Res. 2010;3:317–325. [Google Scholar]
  • 33.Xu W, Zhu YS, Chen X, Wang J, Tao L, Xu S, Liu T, Song HW. A novel strategy for improving upconversion luminescence of NaYF4:Yb,Er nanocrystals by coupling with hybrids of silver plasmon nanostructures and poly(methyl methacrylate) photonic crystals. Nano Res. 2013;6:795–807. [Google Scholar]
  • 34.Deng ML, Wang LY. Unexpected luminescence enhancement of upconverting nanocrystals by cation exchange with well retained small particle size. Nano Res. 2014;7:782–793. [Google Scholar]
  • 35.Chen G, Chen FS, Liu XH, Ma W, Luo HM, Li JH, Ma RZ, Qiu GZ. Hollow spherical rare-earth-doped yttrium oxysulfate: A novel structure for upconversion. Nano Res. 2014;7:1093–1102. [Google Scholar]
  • 36.Wang J, Wei T, Li XY, Zhang BH, Wang JX, Huang C, Yuan Q. Near-infrared-light-mediated imaging of latent fingerprints based on molecular recognition. Angew Chem Int Ed. 2014;53:1616–1620. doi: 10.1002/anie.201308843. [DOI] [PubMed] [Google Scholar]
  • 37.Wang M, Abbineni G, Clevenger A, Mao CB, Xu SK. Upconversion nanoparticles: synthesis, surface modification and biological applications. Nanomedicine: NBM. 2011;7:710–729. doi: 10.1016/j.nano.2011.02.013. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 38.Wang F, Banerjee D, Liu YS, Chen XY, Liu XG. Upconversion nanoparticles in biological labeling, imaging, and therapy. Analyst. 2010;135:1839–1854. doi: 10.1039/c0an00144a. [DOI] [PubMed] [Google Scholar]
  • 39.Chatterjee DK, Gnanasammandhan MK, Zhang Y. Small upconverting fluorescent nanoparticles for biomedical applications. Small. 2010;6:2781–2795. doi: 10.1002/smll.201000418. [DOI] [PubMed] [Google Scholar]
  • 40.Wang M, Hou W, Mi CC, Wang WX, Xu ZR, Teng HH, Mao CB, Xu SK. Immunoassay of goat antihuman immunoglobulin G antibody based on luminescence resonance energy transfer between near-infrared responsive NaYF4:Yb,Er upconversion fluorescent nanoparticles and gold nanoparticles. Anal Chem. 2009;81:8783–8789. doi: 10.1021/ac901808q. [DOI] [PubMed] [Google Scholar]
  • 41.Ma RL, Bullock E, Maynard P, Reedy B, Shimmon R, Lennard C, Roux C, McDonagh A. Fingermark detection on non-porous and semi-porous surfaces using NaYF4:Er,Yb up-converter particles. Forensic Sci Int. 2011;207:145–149. doi: 10.1016/j.forsciint.2010.09.020. [DOI] [PubMed] [Google Scholar]
  • 42.Wang M, Mi CC, Wang WX, Liu CH, Wu YF, Xu ZR, Mao CB, Xu SK. Immunolabeling and NIR-excited fluorescent imaging of HeLa cells by using NaYF4:Yb,Er upconversion nanoparticles. ACS Nano. 2009;3:1580–1586. doi: 10.1021/nn900491j. [DOI] [PubMed] [Google Scholar]
  • 43.Wang M, Mi CC, Zhang YX, Liu JL, Li F, Mao CB, Xu SK. NIR-responsive silica-coated NaYbF4:Er/Tm/Ho upconversion fluorescent nanoparticles with tunable emission colors and their applications in immunolabeling and fluorescent imaging of cancer cells. J Phys Chem C. 2009;113:19021–19027. doi: 10.1021/jp906394z. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 44.Mai HX, Zhang YW, Sun LD, Yan CH. Highly efficient multicolor up-conversion emissions and their mechanisms of monodisperse NaYF4:Yb,Er core and core/shell–structured nanocrystals. J Phys Chem C. 2007;111:13721–13729. [Google Scholar]
  • 45.Mai HX, Zhang YW, Sun LD, Yan CH. Size- and phase-controlled synthesis of monodisperse NaYF4:Yb,Er nanocrystals from a unique delayed nucleation pathway monitored with upconversion spectroscopy. J Phys Chem C. 2007;111:13730–13739. [Google Scholar]
  • 46.Yi GS, Chow GM. Synthesis of hexagonal-phase NaYF4:Yb,Er and NaYF4:Yb,Tm nanocrystals with efficient up-conversion fluorescence. Adv Funct Mater. 2006;16:2324–2329. [Google Scholar]
  • 47.Wang X, Zhuang J, Peng Q, Li YD. A general strategy for nanocrystal synthesis. Nature. 2005;437:121–124. doi: 10.1038/nature03968. [DOI] [PubMed] [Google Scholar]
  • 48.Liang X, Wang X, Zhuang J, Peng Q, Li YD. Synthesis of NaYF4 nanocrystals with predictable phase and shape. Adv Funct Mater. 2007;17:2757–2765. [Google Scholar]
  • 49.Wang LY, Li YD. Controlled synthesis and luminescence of lanthanide doped NaYF4 nanocrystals. Chem Mater. 2007;19:727–734. [Google Scholar]
  • 50.Thoma RE, Insley H, Hebert GM. Sodium fluoride-lanthanide trifluoride systems. Inorg Chem. 1966;5:1222–1229. [Google Scholar]
  • 51.Mai HX, Zhang YW, Si R, Yan ZG, Sun LD, You LP, Yan CH. High-quality sodium rare-earth fluoride nanocrystals: Controlled synthesis and optical properties. J Am Chem Soc. 2006;128:6426–6436. doi: 10.1021/ja060212h. [DOI] [PubMed] [Google Scholar]
  • 52.Thomas GL. Physics of fingerprints and their detection. J Phys E: Sci Instrum. 1978;11:722–731. [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

SI
NIHMS797020-supplement-SI.pdf (1.3MB, pdf)

RESOURCES