Time-Gated Imaging of Latent Fingerprints with Level 3 Details Achieved by Persistent Luminescent Fluoride Nanoparticles

Daylight Visualization of Latent Fingerprints Exceeding Level 3 Details through Contradictory Electrostatic and Hydrogen-Bonding Interactions

Daylight visualization of latent fingerprints (LFPs) is highly desirable due to its convenience and safety for inspectors. However, achieving this visualization with details exceeding level 3 using nontoxic materials presents a significant challenge. Here, we address this challenge by utilizing cyclosiloxane-linked fluorescent porous polymers (FPPs) as the developers. These FPPs were synthesized from 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane and brominated monomers via Heck reactions. The resulting FPPs, available as powders in various colors, exhibit high porosity and strong fluorescence. By employing the classical powder dusting method with FPPs, LFPs with level 1-3 details become visible on various substrates, including copper, iron, aluminum, tinfoil, and wood, under daylight. This approach provides high resolution and contrast with strong resistance to background interference on colored substrates. The efficient visualization is attributed to contradictory electrostatic and hydrogen-bonding interactions between FPPs and fingerprint secretions, which ensure strong adhesion of the materials exclusively to the ridges of fingerprints rather than the furrows. Furthermore, the FPPs are noncytotoxic and do not impede DNA extraction and identification after LFP visualization. This study represents the first example of daylight visualization of LFPs with details surpassing level 3 using nontoxic developers, thereby mitigating the risks associated with material toxicity and light exposure for inspectors. These findings highlight the potential of FPPs as efficient developers for LFP visualization in crime scenes. This straightforward and broadly applicable protocol may pave the way for further advancements in daylight visualization methods for LFPs.

Flexible Alternating-Current Electroluminescent Devices for Reliable Identification of Fingerprints

Flexible bioelectronic devices, which can directly detect various external stimuli or biosignals and communicate the information to the users, have been broadly investigated due to the increasing demand for wearable devices. Among them, alternating-current electroluminescence (ACEL) devices are proposed as sensitive sensing systems for various targets, such as fingerprints. Herein, we propose a method for preparing high-performance ACEL devices by using an Ag electrode, polyethylene terephthalate (PET) substrate, FKM/EMI ionogel, and ZnS:Cu/BaTiO3/Ecoflex emissive layer. Their influence has also been studied for achieving high performances. The results demonstrate that the prepared ACEL devices can achieve high performances of emitting bright green and blue light when contacted with various ionic liquids. Significantly, they achieved good sensing performance for detecting Na+ with a limit of detection at 17.1 μM in the linear range of 100-800 mM. Moreover, the ACEL devices can be used for identity recognition, as they are capable of efficient collection and distinguishing of fingerprints. Even the characteristics of fingerprints collected from bending surfaces or contaminated fingers could be distinguished by the naked eyes. Compared with commercial fingerprint devices, our ACEL devices exhibit superior performance in fingerprint identification. High-resolution and three-dimensional image analysis further validates the reliability of our ACEL devices in fingerprint collection and identification. As such, we believe that the designed ACEL devices have very promising application prospects in many fields.

X-ray/γ-ray/Ultrasound-Activated Persistent Luminescence Phosphors for Deep Tissue Bioimaging and Therapy

Persistent luminescence phosphors (PLPs) can remain luminescent after excitation ceases and have been widely explored in bioimaging and therapy since 2007. In bioimaging, PLPs can efficiently avoid tissue autofluorescence and light scattering interference by collecting persistent luminescence signals after the end of excitation. Outstanding signal-to-background ratios, high sensitivity, and resolution have been achieved in bioimaging with PLPs. In therapy, PLPs can continuously produce therapeutic molecules such as reactive oxygen species after removing excitation sources, which realizes sustained therapeutic activity after a single dose of light stimulation. However, most PLPs are activated by ultraviolet or visible light, which makes it difficult to reactivate the PLPs in vivo, particularly in deep tissues. In recent years, excitation sources with deep tissue penetration have been explored to activate PLPs, including X-ray, γ-ray, and ultrasound. Researchers found that various inorganic and organic PLPs can be activated by X-ray, γ-ray, and ultrasound, making these PLPs valuable in the imaging and therapy of deep-seated tumors. These X-ray/γ-ray/ultrasound-activated PLPs have not been systematically introduced in previous reviews. In this review, we summarize the recently developed inorganic and organic PLPs that can be activated by X-ray, γ-ray, and ultrasound to produce persistent luminescence. The biomedical applications of these PLPs in deep-tissue bioimaging and therapy are also discussed. This review can provide instructions for the design of PLPs with deep-tissue-renewable persistent luminescence and further promote the applications of PLPs in phototheranostics, noninvasive biosensing devices, and energy harvesting.

Bioimaging and prospects of night pearls-based persistence phosphors in cancer diagnostics

Inorganic persistent phosphors feature great potential for cancer diagnosis due to the long luminescence lifetime, low background scattering, and minimal autofluorescence. With the prominent advantages of near-infrared light, such as deep penetration, high resolution, low autofluorescence, and tissue absorption, persistent phosphors can be used for deep bioimaging. We focus on highlighting inorganic persistent phosphors, emphasizing the synthesis methods and applications in cancer diagnostics. Typical synthetic methods such as the high-temperature solid state, thermal decomposition, hydrothermal/solvothermal, and template methods are proposed to obtain small-size phosphors for biological organisms. The luminescence mechanisms of inorganic persistent phosphors with different excitation are discussed and effective matrixes including galliumate, germanium, aluminate, and fluoride are explored. Finally, the current directions where inorganic persistent phosphors can continue to be optimized and how to further overcome the challenges in cancer diagnosis are summarized.

Enhanced Storage Capacity via Anion Substitution for Advanced Delayed X-ray Detection

X-ray radiation information storage, characterized by its ability to detect radiation with delayed readings, shows great promise in enabling reliable and readily accessible X-ray imaging and dosimetry in situations where conventional detectors may not be feasible. However, the lack of specific strategies to enhance the memory capability dramatically hampers its further development. Here, we present an effective anion substitution strategy to enhance the storage capability of NaLuF4:Tb3+ nanocrystals attributed to the increased concentration of trapping centers under X-ray irradiation. The stored radiation information can be read out as optical brightness via thermal, 980 nm laser, or mechanical stimulation, avoiding real-time measurement under ionizing radiation. Moreover, the radiation information can be maintained for more than 13 days, and the imaging resolution reaches 14.3 lp mm-1. These results demonstrate that anion substitution methods can effectively achieve high storage capability and broaden the application scope of X-ray information storage.

Bimodal persistent luminescence for autofluorescence-free ratiometric biosensing

In optical biosensing, analyte-independent factors such as autofluorescence interference and excitation source fluctuation decrease the sensitivity and accuracy. Herein, we reported a bimodal persistent luminescence strategy to design dual-emissive persistent luminescence nanoparticles (PLNPs) with built-in self-calibration to preclude interference from analyte-independent factors in biosensing. As a proof of concept, ZnGa2O4:Cr PLNPs with emissions at both 490 nm and 695 nm were designed. The I490/I695 ratio of ZnGa2O4:Cr was readily adjusted by simply changing the doping concentration of Cr3+. The ZnGa2O4:Cr PLNPs were employed for the ratiometric detection of urinary mesna. A good linear relationship between the I490/I695 ratio of ZnGa2O4:Cr-based nanoprobe and the concentration of mesna was obtained in the range of 0-40 μM. The limit of detection was about 0.40 μM. Results showed that autofluorescence interference from urine was totally eliminated by collecting the persistent luminescence signal of ZnGa2O4:Cr after excitation ceased. Moreover, the built-in self-calibration feature of the ratiometric ZnGa2O4:Cr PLNPs efficiently suppressed the interference from fluctuations in instrumental parameters during urinary mesna detection. The recovery rates of mesna in the spiked urine samples are in the range of 99.1~109.0%, showing the reliability of the ratiometric ZnGa2O4:Cr PLNPs in urinary mesna detection. ZnGa2O4:Cr can further be expanded to the detection of other analytes in complex matrices. This study may open new opportunities for the design of dual-emissive PLNPs with tunable ratios of emission intensity, and it can further promote the applications of optical biosensing in disease diagnosis, food safety, and environmental monitoring.

Nonstoichiometric Nanocubes with a Controllable Morphology and Persistent Luminescence for Autofluorescence-Free Biosensing

Persistent luminescence nanoparticles (PLNPs) have shown special advantages in areas such as bioimaging, cancer therapy, stress sensing, and photo-biocatalysis. However, the lack of methods for controllable synthesis of PLNPs with uniform morphologies and strong persistent luminescence has seriously hindered the applications of PLNPs. Herein, we reported that modifying the electronic structures of zinc gallogermanate (ZGGO) PLNPs by nonstoichiometric reactions can produce highly uniform nanocubes with controllable size and persistent luminescence. By nonstoichiometric increase of the Ge/Ga ratio in ZGGO, the ZGGO PLNPs were transformed from a mixture of nanocubes and small nanospheres into highly symmetrical and uniform large nanocubes, accompanied by the enhancement of persistent luminescence intensity by about 3.7 times. Moreover, we found that ZGGO PLNPs were responsive to reactive oxygen species (ROS), that is, the persistent luminescence of ZGGO can be quenched by ROS. Autofluorescence-free serum ROS detection was achieved with the developed PLNPs. Further, a biosensing assay for glucose oxidase (GOx) was designed based on the responsiveness of ZGGO PLNPs to H2O2. This study may pave a new way for better control of PLNPs' size, morphology, and persistent luminescence, and it can further promote the applications of PLNPs in areas ranging from theranostics to solar energy utilization.

Perspective and Prospects on persistent luminescent nanoparticles for biological imaging and tumor therapy

Persistent luminescent nanoparticles (PLNPs) are photoluminescent materials that can still emit luminescence after the cessation of the excitation light source. In recent years, due to their unique optical properties, the PLNPs have attracted extensive attention in the biomedical field. Since the PLNPs effectively eliminate autofluorescence interference from biological tissues, many researchers have contributed a lot of work in the fields of biological imaging and tumor therapy. This article mainly introduces the synthesis methods of the PLNPs and their progress in the application of biological imaging and tumor therapy, as well as the challenges and development prospects.

Advancing X-ray Luminescence for Imaging, Biosensing, and Theragnostics

X-ray luminescence is an optical phenomenon in which chemical compounds known as scintillators can emit short-wavelength light upon the excitation of X-ray photons. Since X-rays exhibit well-recognized advantages of deep penetration toward tissues and a minimal autofluorescence background in biological samples, X-ray luminescence has been increasingly becoming a promising optical tool for tackling the challenges in the fields of imaging, biosensing, and theragnostics. In recent years, the emergence of nanocrystal scintillators have further expanded the application scenarios of X-ray luminescence, such as high-resolution X-ray imaging, autofluorescence-free detection of biomarkers, and noninvasive phototherapy in deep tissues. Meanwhile, X-ray luminescence holds great promise in breaking the depth dependency of deep-seated lesion treatment and achieving synergistic radiotherapy with phototherapy.In this Account, we provide an overview of recent advances in developing advanced X-ray luminescence for applications in imaging, biosensing, theragnostics, and optogenetics neuromodulation. We first introduce solution-processed lead halide all-inorganic perovskite nanocrystal scintillators that are able to convert X-ray photons to multicolor X-ray luminescence. We have developed a perovskite nanoscintillator-based X-ray detector for high-resolution X-ray imaging of the internal structure of electronic circuits and biological samples. We further advanced the development of flexible X-ray luminescence imaging using solution-processable lanthanide-doped nanoscintillators featuring long-lived X-ray luminescence to image three-dimensional irregularly shaped objects. We also outline the general principles of high-contrast in vivo X-ray luminescence imaging which combines nanoscintillators with functional biomolecules such as aptamers, peptides, and antibodies. High-quality X-ray luminescence nanoprobes were engineered to achieve the high-sensitivity detection of various biomarkers, which enabled the avoidance of interference from the biological matrix autofluorescence and photon scattering. By marrying X-ray luminescence probes with stimuli-responsive materials, multifunctional theragnostic nanosystems were constructed for on-demand synergistic gas radiotherapy with excellent therapeutic effects. By taking advantage of the capability of X-rays to penetrate the skull, we also demonstrated the development of controllable, wireless optogenetic neuromodulation using X-ray luminescence probes while obviating damage from traditional optical fibers. Furthermore, we discussed in detail some challenges and future development of X-ray luminescence in terms of scintillator synthesis and surface modification, mechanism studies, and their other potential applications to provide useful guidance for further advancing the development of X-ray luminescence.

Controllable Synthesis, Formation Process, and Luminescence Performances of Diverse Yttrium Compounds with Hollow Structures

Hollow spherical Y₂O₃ and YBO₃ have been prepared by a facile template-directed strategy using phenol-formaldehyde (PF) resin spheres as templates. The PF@Y(OH)CO₃ precursor can be fabricated by a simple precipitation route. The Y₂O₃ hollow spheres are obtained via a direct annealing process, and the hollow spherical YBO₃ are fabricated via a hydrothermal route followed by an annealing process at the expense of the same PF@Y(OH)CO₃ precursor. The whole synthesis procedure is performed in aqueous solution without any surfactant or catalyst. Moreover, YVO₄ quasi-octahedral microcrystals with spherical holes are obtained. The formation mechanisms of the yttrium compounds with different morphologies have been discussed. By incorporating proper rare earth activator ions into the Y₂O₃, YBO₃, and YVO₄ hosts, the as-synthesized luminescent materials can exhibit eminent performances with both down-conversion and up-conversion luminescence. Furthermore, the as-fabricated light-emitting diode (LED) devices can emit dazzling characteristic emission light, which reveals that the phosphors have application potential in lighting and displays. This simple synthesis strategy may provide a new idea for the fabrication of inorganic compounds with perfect hollow structures and excellent properties.