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Cell temperature monitoring is of great importance to uncover temperature-dependent intracellular events and regulate cellular functions. However, it remains a great challenge to precisely probe the localized temperature status in living cells. Herein, we report a strategy for in situ temperature mapping on an immune cell membrane for the first time, which was achieved by using the lanthanide-doped upconversion nanoparticles. The nanothermometer was designed to label the cell membrane by combining metabolic labeling and click chemistry and can leverage ratiometric upconversion luminescence signals to in situ sensitively monitor temperature variation (1.4% K–1). Moreover, a purpose-built upconversion hyperspectral microscope was utilized to synchronously map temperature changes on T cell membrane and visualize intracellular Ca2+influx. This strategy was able to identify a suitable temperature status for facilitating thermally stimulated calcium influx in T cells, thus enabling high-efficiency activation of immune cells. Such findings might advance understandings on thermally dependent biological processes and their regulation methodology.

X-ray imaging and computed tomography (CT) technology, as the important non-destructive measurements, can observe internal structures without destroying the detected sample, which are always used in biological diagnosis to detect tumors, pathologies, and bone damages. It is always a challenge to find materials with a low detection limit, a short exposure time, and high resolution to reduce X-ray damage and acquire high-contrast images. Here, we described a low-cost and high-efficient method to prepare centimeter-sized anthracene crystals, which exhibited intense X-ray radioluminescence with a detection limit of ∼0.108 μGy s–1, which is only one-fifth of the dose typically used for X-ray diagnostics. Additionally, the low absorption reduced the damage in radiation and ensured superior cycle performance. X-ray detectors based on anthracene crystals also exhibited an extremely high resolution of 40 lp mm–1. The CT scanning and reconstruction of a foam sample were then achieved, and the detailed internal structure could be clearly observed. These indicated that organic crystals are expecting to be leading candidate low-cost materials for low-dose and highly sensitive X-ray detection and CT scanning.

Ultrasmall gold nanoclusters (AuNCs) are emerging as promising luminescent nanoprobes for bioimaging due to their fantastic photoluminescence (PL) and renal-clearable ability. However, it remains a great challenge to design them for in vivo sensitive molecular imaging in desired tissues. Herein, we have developed a strategy to tailor the PL and biofate of near-infrared II (NIR-II)-emitting AuNCs via ligand anchoring for improved bioimaging. By optimizing the ligand types in AuNCs and using Er3+-doped lanthanide (Ln) nanoparticles as models, core–satellite Ln@AuNCs assemblies were rationally constructed, which enabled 2.5-fold PL enhancement of AuNCs at 1100 nm and prolonged blood circulation compared to AuNCs. Significantly, Ln@AuNCs with dual intense NIR-II PL (from AuNCs and Er3+) can effectively accumulate in the liver for ratiometric NIR-II imaging of H2S, facilitated by H2S-mediated selective PL quenching of AuNCs. We have then demonstrated the real-time imaging evaluation of liver delivery efficacy and dynamics of two H2S prodrugs. This shows a paradigm to visualize liver H2S delivery and its prodrug screening in vivo. Note that Ln@AuNCs are body-clearable via the hepatobiliary excretion pathway, thus reducing potential long-term toxicity. Such findings may propel the engineering of AuNC nanoprobes for advancing in vivo bioimaging analysis.

Current X-ray imaging technologies involving flat-panel detectors have difficulty in imaging three-dimensional objects because fabrication of large-area, flexible, silicon-based photodetectors on highly curved surfaces remains a challenge1–3. Here we demonstrate ultralong-lived X-ray trapping for flat-panel-free, high-resolution, three-dimensional imaging using a series of solution-processable, lanthanide-doped nanoscintillators. Corroborated by quantum mechanical simulations of defect formation and electronic structures, our experimental characterizations reveal that slow hopping of trapped electrons due to radiation-triggered anionic migration in host lattices can induce more than 30 days of persistent radioluminescence. We further demonstrate X-ray luminescence extension imaging with resolution greater than 20 line pairs per millimetre and optical memory longer than 15 days. These findings provide insight into mechanisms underlying X-ray energy conversion through enduring electron trapping and offer a paradigm to motivate future research in wearable X-ray detectors for patient-centred radiography and mammography, imaging-guided therapeutics, high-energy physics and deep learning in radiology.

The growing demands for X-ray imaging applications impose diverse and stringent requirements on advanced X-ray detectors. Among these, flexibility stands out as the most expected characteristic for next-generation X-ray detectors. Flexible X-ray detectors can spatially conform to nonflat surfaces, substantially improving the imaging resolution, reducing the X-ray exposure dosage, and enabling extended application opportunities that are hardly achievable by conventional rigid flat-panel detectors. Over the past years, indirect- and direct-conversion flexible X-ray detectors have made marvelous achievements. In particular, microscale and nanoscale engineering technologies play a pivotal role in defining the optical, electrical, and mechanical properties of flexible X-ray detectors. In this Perspective, we spotlight recent landmark advancements in flexible X-ray detectors from the aspects of micro/nano engineering strategies, which are broadly categorized into two prevailing modalities: materials-in-substrate and materials-on-substrate. We also discuss existing challenges hindering the development of flexible X-ray detectors, as well as prospective research opportunities to mitigate these issues.

Optical biosensors that enable highly sensitive detection of biomolecules are useful for applications in early disease diagnosis. However, the presence of UV–vis-induced background fluorescence in biological samples is still challenging. Thanks to the weak scattering and nearly no absorption of biological chromophores under X-ray excitation, we describe the development of an X-ray nanocrystal scintillator-based aptasensor that is able to achieve sensitive and homogeneous detection of target biomolecules. In this work, aptamer-labeled lanthanide-doped nanocrystal scintillators was designed to rapidly and sensitively detect lysozyme via fluorescence resonance energy transfer (FRET) in human serum samples. Benefiting from the use of low-dose X-ray as an excitation source and high-efficiency luminescence of heavy atoms-contained nanocrystals, the proposed X-ray nanocrystal scintillator-based aptasensor can readily detect lysozyme with a high sensitivity up to 0.94 nM, as well as an excellent specificity and sample recoveries. Thus, our technique suggests that the X-ray scintillating aptasensor can create a new generation of autofluorescence-free high-sensitivity strategy for biomarker sensing in biomedical applications.

Conventional photosensitizer-based photodynamic therapy is triggered by UV-light irradiation and depends on oxygen. However, it is hard to be applied to the deep and hypoxic tumor. To address this issue, we reported a new kind of g-C3N4nanosheet decorated with gold nanoparticles (AuNPs), which could generate a high amount of reactive oxygen species (ROS) under a 670 nm laser irradiation in an oxygen-free environment. This synthesized semiconductor–metal heterojunction served as a superior photodynamic agent, showing prominent cancer cell-killing and tumor growth-suppressing effects in the presence of a 670 nm light and g-C3N4–AuNP composites, and its excellent ROS generation property was also validated by further bactericidal experiment.

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.