Optical Tagging Research Articles

Optically driven ultraviolet-C glowing from an in situ trapping-detrapping approach.

In recent years, the world has witnessed rapid progress in research on ultraviolet luminescent materials, ranging from high-level anticounterfeiting and solar-blind optical tagging to antibacterial applications. In particular, a background-signal free solar-blind surveillance of ultraviolet-C photons provides an opportunity in bright indoor and outdoor environments. However, ambient daylight or inevitable external photostimulation is always eliminated or underestimated in the research of persistent phosphors. Herein, an in situ trapping-detrapping experimental procedure is employed to reveal more information on the total trap energy and trap modulations after photostimulation. Our findings reveal the presence of optically active trapping defects with photostimulated detrapping and retrapping behavior. This work provides a fundamental advance in revealing the trap distribution and trap reshuffling during glowing-in-the-daylight events, offering what we believe to be new insights into manipulating traps.

Narrowband Ultraviolet-B Persistent Luminescence in an Indoor-Lighting Environment through Energy Transfer from Host Excitons to Gd3+ Emitters in ScPO4.

Narrowband ultraviolet-B (NB-UVB) luminescent materials are characterized by high photon energy, narrow spectral width, and visible-blind emission, thus holding great promise for photochemistry and photomedicine. However, most NB-UVB phosphors developed so far are photoluminescent, where continuous external excitation is needed. Herein, we realize NB-UVB persistent luminescence (PersL) in an indoor-lighting environment by exploiting the interaction between self-trapped/defect-trapped excitons and Gd3+ emitters in ScPO4. The phosphor shows a self-luminescing feature with a peak maximum at 313 nm with a time duration of >24 h after ceasing X-ray irradiation, which can be clearly imaged by an UVB camera in a bright environment. Spectroscopic and theoretical approaches reveal that thermo- and photo-stimulations of energies trapped at intrinsic lattice defects followed by energy transfer to Gd3+ emitters account for the emergence of the afterglow. The present results can initiate more exploration of NB-UVB PersL phosphors for emerging applications in secret optical tagging and phototherapy.

Photonic Bandgap Fiber Microlaser with Dual‐Band Emission for Integrated Optical Tagging and Sensing

AbstractLasers are emerging as novel photonic tags for single‐cell labeling, anticounterfeiting, and encryption technology due to their narrow linewidth, high spectral multiplexing capacity, and superior stimuli‐responsiveness. These laser‐encoded photonic tags mostly distinguish the heterogeneity but do not yet provide both tagging and sensing of biosamples, which is highly desirable for disease screening. Here, a photonic bandgap (PBG) fiber microlaser that works as a 2D tag and an immunosensor is developed. The tubular PBG structure allows strong light–matter interaction and supports dual‐band lasing in the same optical fiber, enabling massive biosample tagging and sensitive biodetection. By encoding the random resonant peaks in the short‐wave band and multiplexing in the spatial domain, a 2D laser tag is generated with a large encoding capacity (>28500). Immunosensing of microalbumin is realized by using the periodic resonant peaks in the long‐wave band, and a limit of detection of 0.06 ng µL−1is achieved. This work is inspiring for the development of high‐performance, multifunctional integrated devices for disease screening.

X-ray-Excited Long-Lasting Narrowband Ultraviolet-B Persistent Luminescence from Gd3+-Doped Sr2P2O7 Phosphor

Persistent phosphors emitting in the narrowband ultraviolet-B (NB-UVB) spectral region have aroused significant interest, owing to their special self-illuminating feature in realizing many advanced technological applications under excitation-free conditions, such as dermatological therapy and invisible optical tagging. Here, we focus our discussion on a new Gd3+-doped persistent phosphor, Sr2P2O7:Gd3+, which exhibits long-lasting NB-UVB persistent luminescence peaking at 312 nm for more than 24 h after charging by an X-ray beam. The NB-UVB light emission from the charged Sr2P2O7:Gd3+ phosphor can be clearly detected by a UVB camera in bright indoor environment. More importantly, the enhancement of NB-UVB afterglow intensity and decay time can be observed under continuous photostimulation of polychromic indoor ambient light. Furthermore, applying charged Sr2P2O7:Gd3+ phosphors as invisible optical taggants, clear and interference-free recognition of the encrypted message and location of different objects have been realized due to the lack of UVB light in bright indoor environment. The as-prepared Sr2P2O7:Gd3+ persistent phosphor is expected to offer new directional solutions for the development and application of ultraviolet luminescence technology.

Linking the genotypes and phenotypes of cancer cells in heterogenous populations via real-time optical tagging and image analysis.

Linking single-cell genomic or transcriptomic profiles to functional cellular characteristics, in particular time-varying phenotypic changes, could help unravel molecular mechanisms driving the growth of tumour-cell subpopulations. Here we show that a custom-built optical microscope with an ultrawide field of view, fast automated image analysis and a dye activatable by visible light enables the screening and selective photolabelling of cells of interest in large heterogeneous cell populations on the basis of specific functional cellular dynamics, such as fast migration, morphological variation, small-molecule uptake or cell division. Combining such functional single-cell selection with single-cell RNA sequencing allowed us to (1) functionally annotate the transcriptomic profiles of fast-migrating and spindle-shaped MCF10A cells, of fast-migrating MDA-MB-231 cells and of patient-derived head-and-neck squamous carcinoma cells, and (2) identify critical genes and pathways driving aggressive migration and mesenchymal-like morphology in these cells. Functional single-cell selection upstream of single-cell sequencing does not depend on molecular biomarkers, allows for the enrichment of sparse subpopulations of cells, and can facilitate the identification and understanding of the molecular mechanisms underlying functional phenotypes.

A considerable improvement of long-persistent luminescence in LiLuSiO4:Pr3+ phosphors by Sm3+ co-doping for optical tagging applications

A considerable enhancement of UVC afterglow intensity and decay time has been realized in LiLuSiO4:Pr3+ phosphors by Sm3+ co-doping.

Optical Cell Tagging for Spatially Resolved Single-Cell RNA Sequencing.

Single-cell RNA sequencing (scRNA-seq) has emerged as a powerful tool for profiling gene expression of distinct cell populations at the single-cell level. However, the information of the positions of cells within the multicellular samples is missing in scRNA-seq datasets. To overcome this limitation, we herein develop OpTAG (optical cell tagging) as a new chemical platform for attaching functional tags onto cell surfaces in a spatially resolved manner. With OpTAG, we establish OpTAG-seq, which enables spatially resolved scRNA-seq. We apply OpTAG-seq to investigate the spatially defined transcriptional program in migrating cancer cells and identified a list of genes that are potential regulators for cancer cell migration and invasion. OpTAG-seq provides a convenient method for mapping cellular heterogeneity with spatial information within multicellular biological systems.

Optical Cell Tagging for Spatially Resolved Single‐Cell RNA Sequencing

AbstractSingle‐cell RNA sequencing (scRNA‐seq) has emerged as a powerful tool for profiling gene expression of distinct cell populations at the single‐cell level. However, the information of the positions of cells within the multicellular samples is missing in scRNA‐seq datasets. To overcome this limitation, we herein develop OpTAG (optical cell tagging) as a new chemical platform for attaching functional tags onto cell surfaces in a spatially resolved manner. With OpTAG, we establish OpTAG‐seq, which enables spatially resolved scRNA‐seq. We apply OpTAG‐seq to investigate the spatially defined transcriptional program in migrating cancer cells and identified a list of genes that are potential regulators for cancer cell migration and invasion. OpTAG‐seq provides a convenient method for mapping cellular heterogeneity with spatial information within multicellular biological systems.

Fluorescent Convertible Capsule Coding Systems for Individual Cell Labeling and Tracking.

In modern biomedical science and developmental biology, there is significant interest in optical tagging to study individual cell behavior and migration in large cellular populations. However, there is currently no tagging system that can be used for labeling individual cells on demand in situ with subsequent discrimination in between and long-term tracking of individual cells. In this article, we demonstrate such a system based on photoconversion of the fluorescent dye rhodamine B co-confined with carbon nanodots in the volume of micron-sized polyelectrolyte capsules. We show that this new fluorescent convertible capsule coding system is robust and is actively uptaken by cell lines while demonstrating low toxicity. Using a variety of cellular lines, we demonstrate how this tagging system can be used for code-like marking and long-term tracking of multiple individual cells in large cellular populations.

Sunlight-activated long persistent luminescence in the ultraviolet-B spectral region from Bi3+-doped garnet phosphors for covert optical tagging

A series of Bi3+-doped garnet-based UVB persistent phosphors have been developed, which can be conveniently charged by either a standard 254 nm lamp or natural sunlight, producing persistent UVB light emission peaking at 313 nm.

Ultraviolet-C persistent luminescence from the Lu2SiO5:Pr3+ persistent phosphor for solar-blind optical tagging.

Visible and infrared persistent phosphors have gained considerable attention in recent years and are being widely used as glow-in-the-dark materials in dark environments. In contrast, the progress in persistent phosphors emitting at the other end of the spectrum, i.e., the shorter-wavelength ultraviolet-C (UVC; 200-280 nm), is rather slow. Here we report the design and synthesis of a well-performing Pr3+-doped UVC emissive persistent phosphor, Lu2SiO5:Pr3+, which exhibits intense UVC persistent luminescence peaking at 270 nm and a long persistence time of more than 12 h after excitation with a 254 nm UV lamp. Besides, the UVC persistent luminescence of a UV pre-irradiated sample can be repeatedly revived after repeated short-illumination with low-energy white light via a process called photostimulated persistent luminescence. Owing to the distinct spectral features of UVC light and the self-sustained luminescence properties, the UVC persistent luminescence of the Lu2SiO5:Pr3+ persistent phosphor can be clearly monitored and imaged using a corona camera in bright environments including direct sunlight and indoor light. The Lu2SiO5:Pr3+ persistent phosphor is expected to find promising applications in the covert optical tagging field.

The DMCdrive: practical 3D-printable micro-drive system for reliable chronic multi-tetrode recording and optogenetic application in freely behaving rodents

Electrophysiological recording and optogenetic control of neuronal activity in behaving animals have been integral to the elucidation of how neurons and circuits modulate network activity in the encoding and causation of behavior. However, most current electrophysiological methods require substantial economical investments and prior expertise. Further, the inclusion of optogenetics with electrophysiological recordings in freely moving animals adds complexity to the experimental design. Expansion of the technological repertoire across laboratories, research institutes, and countries, demands open access to high-quality devices that can be built with little prior expertise from easily accessible parts of low cost. We here present an affordable, truly easy-to-assemble micro-drive for electrophysiology in combination with optogenetics in freely moving rodents. The DMCdrive is particularly suited for reliable recordings of neurons and network activities over the course of weeks, and simplify optical tagging and manipulation of neurons in the recorded brain region. The highly functional and practical drive design has been optimized for accurate tetrode movement in brain tissue, and remarkably reduced build time. We provide a complete overview of the drive design, its assembly and use, and proof-of-principle demonstration of recordings paired with cell-type-specific optogenetic manipulations in the prefrontal cortex (PFC) of freely moving transgenic mice and rats.

White-light flashlight activated up-conversion luminescence for ultraviolet-B tagging.

Optical tagging technology with emission in the ultraviolet region upon visible-light excitation is promising for objects identified in visually bright environments, while the relevant research is absent. Here we put forward a covert tagging concept, which is based on up-converting phosphors (e.g., Lu3Al5O12:Pr3+) with emission peaking in the ultraviolet-B region (UV-B, 290-320 nm). A white-light flashlight serves as excitation source to make the up-converter emit, and an ultraviolet camera is applied to see such an emission wavelength range. This Letter expands the excitation source for an up-conversion process to a convenient flashlight for the first time, to the best of our knowledge. Moreover, such a flashlight-pumped UV-B tagging technology is generally applicable for many other phosphors, which can be utilized to mark and differentiate objects in commercial, civilian, or military applications.

Persistent Emission of Narrowband Ultraviolet-B Light upon Blue-Light Illumination

Ultraviolet luminescence holds potential for diverse applications. Further development of ultraviolet-luminescence technology, however, is hindered by the common but very inconvenient photoluminescence form. Here we create a form of ultraviolet emission-persistent luminescence in the narrowband ultraviolet-B (NB UVB) region (309--313 nm) upon illumination by a blue light-emitting diode. On this basis, we study the dynamic competition between an up-conversion charging excitation and a photostimulated detrapping upon illumination by the light-emitting diode. Such a competition mechanism, as well as the associated manipulation technique, appears to be generally applicable for many existing phosphors. As a proof of concept, we present an imaging demonstration, showing the potential of the NB-UVB persistent luminescence in the optical tagging field. This work can potentially revolutionize the ways for utilizing persistent luminescence, leading NB-UVB applications to another level.

Sensory coding mechanisms revealed by optical tagging of physiologically defined neuronal types.

Neural circuit analysis relies on having molecular markers for specific cell types. However, for a cell type identified only by its circuit function, the process of identifying markers remains laborious. We developed physiological optical tagging sequencing (PhOTseq), a technique for tagging and expression profiling of cells on the basis of their functional properties. PhOTseq was capable of selecting rare cell types and enriching them by nearly 100-fold. We applied PhOTseq to the challenge of mapping receptor-ligand pairings among pheromone-sensing neurons in mice. Together with in vivo ectopic expression of vomeronasal chemoreceptors, PhOTseq identified the complete combinatorial receptor code for a specific set of ligands.

Cell-type identification in neural circuits

Neuroscience In many cases, a single molecular marker is insufficient to define a specific cell type and may label a few, or a few hundred, physiologically distinguishable cell types. Lee et al. developed a high-throughput technique, called physiological optical tagging sequencing (PhOTseq), for identifying the expression profile of cells that exhibit a particular physiological profile (see the Perspective by Renninger). They used PhOTseq to identify genes encoding vomeronasal receptors in mice, which detect pheromones and subserve social communication. Science , this issue p. [1384][1]; see also p. [1311][2] [1]: /lookup/doi/10.1126/science.aax8055 [2]: /lookup/doi/10.1126/science.aaz8969

Excitation of Guided Waves on a Lossless Dielectric Slab by an E-Polarized Complex Source Point Beam

A lossless slab excited by an E-polarized two-dimensional (2-D) complex source point (CSP) beam is studied analytically. Such a source, unlike a Gaussian beam, satisfies exactly the Helmholtz equation and radiation condition, without paraxial approximation or formulation incompleteness. The guided-waves fields as well as the scattered fields in the regions above and below the slab are determined; in turn, the corresponding powers are directly calculated. Numerical results on the variations of these quantities with respect to the slab electrical thickness, the beam angle of incidence, the source aperture size and location are presented. Substantial power transfer from the finite directive source into each of the slab’s guided waves is recorded especially in the case of near-grazing beam illumination. Such a finding may inspire further theoretical and experimental efforts towards numerous research directions like non-invasive sensing, wireless optical tagging and energy teleportation.

Comb-like scattering realized by cylindrical plasmonic multilayers

We study the comb-like scattering response of cylindrical multilayered plasmonic nanostructures. Through oxide semiconductors with different doping levels, the comb-like scattering made up of multiple Fano resonances can be achieved with enough scattering excursion. Each sharp Fano resonance is associated with a degenerate state between a bipolar cloaking and a bipolar resonant scattering. When the semiconductor shell is thin enough, the scattering response is independent of the core and background materials, and even the size of the nanostructure under quasi-static conditions. The physical mechanism of the proposed comb-like device is explained by using full-wave electromagnetic simulation. Moreover, the scattering cross section of the device with a considerable thickness can exhibit reliable comb-like scattering under different thicknesses and material parameters, which is suitable for optical tagging applications.

Response Patterns of GABAergic Neurons in the Anterior Piriform Cortex of Awake Mice.

Local inhibition by γ-amino butyric acid (GABA)-containing neurons is of vital importance for the operation of sensory cortices. However, the physiological response patterns of cortical GABAergic neurons are poorly understood, especially in the awake condition. Here, we utilized the recently developed optical tagging technique to specifically record GABAergic neurons in the anterior piriform cortex (aPC) in awake mice. The identified aPC GABAergic neurons were stimulated with robotic delivery of 32 distinct odorants, which covered a broad range of functional groups. We found that aPC GABAergic neurons could be divided into 4 types based on their response patterns. Type I, type II, and type III neurons displayed broad excitatory responses to test odorants with different dynamics. Type I neurons were constantly activated during odorant stimulation, whereas type II neurons were only transiently activated at the onset of odorant delivery. In addition, type III neurons displayed transient excitatory responses both at the onset and termination of odorant presentation. Interestingly, type IV neurons were broadly inhibited by most of the odorants. Taken together, aPC GABAergic neurons adopt different strategies to affect the cortical circuitry. Our results will allow for better understanding of the role of cortical GABAergic interneurons in sensory information processing.

Plasmon-enhanced random lasing in bio-compatible networks of cellulose nanofibers

We report on plasmon-enhanced random lasing in bio-compatible light emitting Hydroxypropyl Cellulose (HPC) nanofiber networks doped with gold nanoparticles. HPC nanofibers with a diameter of 260 ± 30 nm were synthesized by a one step, cost-effective and facile electrospinning technique from a solution-containing Rhodamine 6G and Au nanoparticles. Nanoparticles of controlled diameters from 10 nm to 80 nm were dispersed inside the nanofibers and optically characterized using photoluminescence, dark-field spectroscopy, and coherent backscattering measurements. Plasmon-enhanced random lasing was demonstrated with a lower threshold than that in dye-doped identical HPC networks without Au nanoparticles. These findings provide an effective approach for plasmon-enhanced random lasers based on a bio-compatible host matrix that is particularly attractive for biophotonic applications such as fluorescence sensing, optical tagging, and detection.