Recent Trends Concerning Upconversion Nanoparticles and Near-IR Emissive Lanthanide Materials in the Context of Forensic Applications

Abstract

Upconversion nanoparticles (UCNPs) are materials that, upon absorbing multiple photons of low energy (e.g. infrared radiation), subsequently emit a single photon of higher energy, typically within the visible spectrum. The physics of these materials have been the subject of detailed investigations driven by the potential application of these materials as medical imaging devices. One largely overlooked application of UCNPs is forensic science, wherein the ability to produce visible light from infrared light sources would result in a new generation of fingerprint powders that circumvent background interference which can be encountered with visible and ultraviolet light sources. Using lower energy, infrared radiation would simultaneously improve the safety of forensic practitioners who often employ light sources in less than ideal locations. This review article covers the development of UCNPs, the use of infrared radiation to visualise fingerprints by the forensic sciences, and the potential benefits of applying UCNP materials over current approaches.

Interpol review of fingermarks and other body impressions 2016–2019

“…It should be noted that participants required about 10 min to adapt their eyes to the dark, based on the device. Available review : thorough review of ALS in the form of a landscape study covering optical phenomena, filters, trace observation and specificities of commercially-available ALS [ 504 ], recent trends linked to the observation of fingermarks in luminescence or in the NIR domain [ 505 , 506 ]. Acronyms used : ALS (alternate light sources), CA (cyanoacrylate), IND/Zn ((1,2-indanedione containing zinc chloride), NIR (near-infrared), R6G (Rhodamine 6G), RUVIS (reflective ultraviolet imaging system), UV (ultraviolet) …”

“…Available review : thorough review of ALS in the form of a landscape study covering optical phenomena, filters, trace observation and specificities of commercially-available ALS [ 504 ], recent trends linked to the observation of fingermarks in luminescence or in the NIR domain [ 505 , 506 ].…”

Rare Earths—The Answer to Everything

“…Furthermore, sensitization in a discrete Er complex provided highly efficient NIR to visible light upconversion [188]. Among many applications, UC NPs have been used in anti-counterfeiting and forensics [189,190].…”

Improving flow dynamics and storage longevity of a low‐cost phosphorescent fingerprint powder

“…This, and other materials like it [2][3][4], emit exceptionally long-lived colored phosphorescence [5], particularly in shades of blue, aqua, and green [6]. Doped strontium aluminate powders have also been described as nontoxic and nonflammable according to OSHA [7], making this class of material an excellent precursor for forensic and security applications [5,8], however if processed into a nanomaterial, particularly with a dry, dispersible form, the health risks associated with inhalation and exposure will be increased [9]. As a fingerprint powder, the benefits of lanthanidedoped strontium aluminates include manufacture from a relatively low-cost and easily accessible material, and the ability to charge the long-lived phosphorescence using white light, which poses fewer hazards than more energetic wavelengths such as ultraviolet radiation.…”