Persistent luminescence describes the phenomenon whereby luminescence remains after the stoppage of excitation. Recently, upconversion persistent luminescence (UCPL) phosphors that can be directly charged by near-infrared (NIR) light have gained considerable attention due to their promising applications ranging from photonics to biomedicine. However, current lanthanide-based UCPL phosphors show small absorption cross sections and low upconversion charging efficiency. The development of UCPL phosphors faces challenges due to the lack of flexible upconversion charging pathways and poor design flexibility. Herein, we discovered a lattice defect-mediated broadband photon upconversion process and the accompanying NIR-to-NIR UCPL in Cr-doped zinc gallate nanoparticles. The zinc gallate nanoparticles can be directly activated by broadband NIR light in the 700-1000 nm range to produce persistent luminescence at about 700 nm, which is also readily enhanced by rationally tailoring the lattice defects in the phosphors. This proposed UCPL phosphor achieved a signal-to-background ratio of over 200 in bioimaging by efficiently avoiding interference from autofluorescence and light scattering. Our work reported a lattice defect-mediated photon upconversion phenomenon, which significantly expands the horizons for the flexible design of UCPL phosphors toward broad applications ranging from bioimaging to photocatalysis.

Smart stimuli-responsive persistent luminescence materials, combining the various advantages and frontier applications prospects, have gained booming progress in recent years. The trap-controlled property and energy storage capability to respond to external multi-stimulations through diverse luminescence pathways make them attractive in emerging multi-responsive smart platforms. This review aims at the recent advances in trap-controlled luminescence materials for advanced multi-stimuli-responsive smart platforms. The design principles, luminescence mechanisms, and representative stimulations, i.e., thermo-, photo-, mechano-, and X-rays responsiveness, are comprehensively summarized. Various emerging multi-responsive hybrid systems containing trap-controlled luminescence materials are highlighted. Specifically, temperature dependent trapping and de-trapping performance is discussed, from extreme-low temperature to ultra-high temperature conditions. Emerging applications and future perspectives are briefly presented. It is hoped that this review would provide new insights and guidelines for the rational design and performance manipulation of multi-responsive materials for advanced smart platforms.

Near-infrared (NIR) phosphors have emerged as novel luminescent materials across various fields due to their unique advantages of high penetration and invisibility. However, there is currently a lack of intelligent NIR phosphors that can achieve multimode stimuli responsive for sensing applications. In this study, we employed a high-temperature solid-phase reaction to incorporate Pr3+ into Cr3+-doped gallate magnetite SrGa12O19 phosphor, yielding a multimode luminescent intelligent NIR phosphor. Also, due to the inherent cation vacancies and defects in the matrix, the material not only exhibits brighter photoluminescence but also exhibits distinct NIR mechanoluminescence at a lower load. Notably, Pr3+-doped SrGa12O19:Cr3+ also demonstrates extended persistent luminescence and thermoluminescence effects. Finally, we combined the phosphor with the blue LED chip to develop a new multifunctional NIR pc-LED. Leveraging NIR\'s unique penetrating ability, it can persist in biological tissues for prolonged periods, enabling optical inspection and offering a novel approach to password protection for anticounterfeiting measures. This intelligent NIR phosphor solution significantly expands the application potential of NIR light in food quality assessment and analysis.

Fluorescent nanosensors have revolutionized diagnostics and our ability to monitor cellular dynamics. Yet, distinguishing sensor signals from autofluorescence remains a challenge. Here, we merged optode-based sensing with near-infrared-emitting ZnGa2O4:Cr3+ persistent luminescence nanoparticles (PLNPs) to create nanocomposites for autofluorescence-free \"glow-in-the-dark\" sensing. Hydrophobic modification and incorporation of the persistent luminescence nanoparticles into an optode-based nanoparticle core yielded persistent luminescence nanosensors (PLNs) for five analytes (K+, Na+, Ca2+, pH, and O2) via two distinct mechanisms. We demonstrated the viability of the PLNs by quantifying K+ in fetal bovine serum, calibrating the pH PLNs in the same, and ratiometrically monitoring O2 metabolism in cultures of Saccharomyces cerevisiae, all the while overcoming their respective autofluorescence signatures. This highly modular platform allows for facile tuning of the sensing functionality, optical properties, and surface chemistry and promises high signal-to-noise ratios in complex optical environments.

The safety of luminescence sensors and probes used in food packaging should be seriously considered, while most luminescence sensors were artificially synthesized with unclear toxicity, and cannot be directly used as indicators that were in contact with food. To overcome this problem, a humidity indicator based on an edible plant tissue was developed without any chemical processing. We found that garlic bulbs could emit significant persistent luminescence after drying at room temperature. The luminescence lifetime decreases from hundreds of milliseconds to tens of milliseconds as humidity increases. The long-lived luminescence could easily be detected through smartphones without any sophisticated instruments. The edible garlic is expected to be used as a humidity indicator in food packaging without worrying about food safety. Furthermore, the interference of scattered light and short-lived fluorescence from foods and packages can be eliminated in time-resolved luminescence imaging, greatly increasing the signal-to-noise ratio.

Photodynamic therapy (PDT) is a promising modality for cancer treatment. However, limited tissue penetration of external radiation and complicated tumor microenvironments (TMEs) restrict the antitumor efficiency of PDT. Herein, we report an energy-storing DNA-based hydrogel, which enables tumor-selective PDT without external radiation and regulates TMEs to achieve boosted PDT-mediated tumor immunotherapy. The system is constructed with two ultralong single-stranded DNA chains, which programmed partial complementary sequences and repeated G-quadruplex forming AS1411 aptamer for photosensitizer loading via hydrophobic interactions and π-π stacking. Then, energy-storing persistent luminescent nanoparticles are incorporated to sensitize PDT selectively at tumor site without external irradiation, generating tumor antigen to agitate antitumor immune response. The system catalytically generates O2 to alleviate hypoxia and releases inhibitors to reverse the IDO-related immunosuppression, synergistically remodeling the TMEs. In the mouse model of breast cancer, this hydrogel shows a remarkable tumor suppression rate of 78.3 %. Our study represents a new paradigm of photodynamic immunotherapy against cancer by combining laser-free fashion and TMEs remodeling.

Discovering multifunctional luminescent materials to meet the demands of modern spectroscopy is of great significance. However, it is a standing challenge to enable multiple luminescence properties in a single material system via single metal ion doping. Here, we report the inherently Bi3+/Bi2+ codoped Ca3Ga2Ge3O12 persistent phosphor where Bi3+ is in situ reduced to Bi2+. This phosphor can act as an efficient multimodal luminescence material, which simultaneously exhibits long-lasting (>12 h) ultraviolet-B (UVB) and near-infrared (NIR) dual-band persistent luminescence after irradiation by 254 nm ultraviolet (UV) light. UVB and NIR afterglow are ascribed to the distinct Bi3+ and Bi2+ emitters, respectively, proven by comprehensive spectroscopic investigations including X-ray absorption near-edge structure spectra and X-ray photoelectron spectroscopy. Besides, this phosphor also exhibits exceptional photochromic features, accompanied by a rapid body color transformation from white to brown in response to 254 nm UV light within 60 s and excellent recovery capacity upon thermal or blue/white light stimulation. The combination of UVB persistent luminescence of Bi3+ and NIR afterglow of Bi2+ coupled with reversible white-to-brown photochromism phenomenon offers one type of promising multifunctional luminescence material, showing potential to be used for optical storage and anti-counterfeiting applications.

Lanthanide-doped scintillators have the ability to convert the absorbed X-ray irradiation into ultraviolet (UV), visible (Vis), or near-infrared (NIR) light. Lanthanide-doped scintillators with excellent persistent luminescence (PersL) are emerging as a new class of PersL materials recently. They have attracted great attention due to their unique \"self-luminescence\" characteristic and potential applications. In this review, we comb through and focus on current developments of lanthanide-doped persistent luminescent scintillators (PersLSs), including their PersL mechanism, synthetic methods, tuning of PersL properties (e. g. emission wavelength, intensity, and duration time), as well as their promising applications (e. g. information storage, encryption, anti-counterfeiting, bio-imaging, and photodynamic therapy). We hope this review will provide valuable guidance for the future development of PersLSs.

Anticounterfeiting plays an essential role in authenticating genuine documents and combating forged products. To further advance the anticounterfeiting technology, there is a strong demand to design new functional materials with unique properties that will be appropriate for making multimode complex security labels. Recently, dynamic security labels have emerged as a new type of advanced anticounterfeiting method as they can hold a much higher security level than the traditional static ones. In this work, we report that calcium zinc germanate (CZGO) clinopyroxenes doped with lead ions have several interesting optical properties, such as dynamic fluorescence, long persistent luminescence, and photochromism. We find that the concentration of lead dopants can significantly impact the reaction kinetics as well as the crystallinity and luminescence properties of CZGO phosphors. By fully utilizing these unique properties, we have successfully fabricated several security labels with multilevel information encoding and dynamic optical performance. The combination of multimode and dynamic luminescence makes these labels extremely challenging to illegally duplicate. With further optimization, this lead-doped CZGO clinopyroxene can be well-integrated into modern anticounterfeiting techniques that will generate highly secure anticounterfeiting labels to combat fake products.

Atherosclerosis (AS) is a crucial contributor to various cardiovascular diseases (CVDs), which seriously threaten human life and health. Early and accurate recognition of AS plaques is essential for the prevention and treatment of CVD. Herein, we introduce an AS-targeting nanoprobe based on near-infrared (NIR) persistent luminescence nanoparticles (PLNPs), developing a highly sensitive NIR persistent luminescence (PersL) AS plaque imaging technique and successfully realizing early AS plaque detection. The nanoprobe exhibits good monodispersity and regular spherical morphology and also owns exceptional NIR PersL performance upon repetitive irradiation by biological window light. The surface-conjugated antibody (anti-osteopontin) endowed nanoprobe excellent targeting ability to foam cells within plaques. After intravenously injected nanoprobe into AS model mice, the highly sensitive PersL imaging technique can accurately detect AS plaques prior to ultrasonography (US) and magnetic resonance imaging (MRI). Specifically, the NIR PersL imaging reveals AS plaques at the earliest within 2 weeks, with higher signal-to-background ratio (SBR) up to 5.72. Based on this technique, the nanoprobe has great potential for applications in the prevention and treatment of CVD, the study of AS pathogenesis, and the screening of anti-AS drugs.