Rapid Visualization of Latent Fingerprints with Color‐Tunable Solid Fluorescent Carbon Dots

Abstract

Latent fingerprints (LFPs) imaging is the most important approach to identify individuals, and there is a persisting need for the development of simple, rapid, accurate, and universal LFPs recognition methods. The nitrogen‐ and sulfur‐doped solid fluorescent carbon dots (N,S‐SFCD) are synthesized with a simple microwave‐assisted method by using l‐glutathione and citric acid as precursors. The obtained N,S‐SFCD has a uniform size from 2 to 7 nm with quantum yield over 48%. The presence of heteroatoms and functional groups on the surface endows the N,S‐SFCD with good dispersibility and strong fluorescence emission, and overcomes the typical aggregation‐induced fluorescence quenching, thus allowing the N,S‐SFCD to be used in both solution and their powder forms. Furthermore, the color‐tunable fluorescence, electrostatic interaction with fingerprints, and good stability enable N, S‐SFCD to act as an excellent chemosensor for fluorescence imaging. LFPs are detected with high resolution through powder method, and their second‐ and third‐level substructures are clearly identified. The method is validated for LFPs visualization on various substrates, and aged (7, 15, and 30 d) LFPs can also be successfully stained with N,S‐SFCD. The results demonstrate that the N,S‐SFCD as a developer has great potential in LFPs imaging for forensic investigations.

Nanoparticles used for fingermark detection—A comprehensive review

“…Two research groups reported the use of a powder containing only C‐dots (G. Ren et al, ; C. Wang, Zhou, et al, ). Sebaceous‐rich fingermarks were successfully detected on silicon wafers (G. Ren, Meng, et al, ).…”

“…Instead of immersing the substrate into a solution, two different groups tried to spray the C‐dots (J. Chen et al, ; C. Wang, Zhou, et al, ). Chen et al used red‐emitting C‐dots in a 0.1 M hydrochloric acid solution (J. Chen, Wei, et al, ).…”

“…Luminescent fingermarks were obtained on glass, aluminum, leather, and plastic, but no information was provided regarding the type and age of the detected impressions. Wang et al, mentioned in the previous section, also tried to apply their C‐dot powder in liquid form through the use of an ultrasonic nebulizer (C. Wang, Zhou, et al, ). Spray application gave results similar to those obtained by powder dusting.…”

Novel organic–inorganic hybrid powder SrGa12O19:Mn2+–ethyl cellulose for efficient latent fingerprint recognitionviatime-gated fluorescence

“…5,8,9 The photoluminescence detection of LFPs is considered to be a more effective approach due to its higher selectivity and contrast than traditional methods such as iodine fuming and vacuum metal deposition. 10,11 Many photoluminescent probe candidates have been reported for LFP imaging, such as conjugated polymer nanoparticles, 12,13 nanophosphors, 14 organic aggregation-induced emission uorophores, 4,15 noble metal nanoclusters, [16][17][18] semiconductor quantum dots, 8,19 and rare earth upconversion uorescent nanomaterials. 20,21 However, these materials suffer from some shortcomings; for example, using noble metals increases the cost of the photoluminescent probes.…”

“…14,34 The resolution and contrast of imaging can be enhanced by using organic matter such as coumarin A with functional groups that generate electrostatic interactions to adhere the LFPs on the surface of the uorescent powder. 4,5,8,22 Herein, we successfully designed and synthesized a LFP probe by using a simple organic-inorganic hybrid strategy to combine the inorganic aerglow phosphor SrGa 12 O 19 :Mn 2+ (SGO:Mn) and ethyl cellulose (EC). SGO is a superior aerglow host lattice, as reported in our previous works, and the proper crystal eld environment for Mn 2+ ions' narrow band emitting can be provided by the SGO host.…”