Activatable Lanthanide Nanoprobes with Dye-Sensitized Second Near-Infrared Luminescence for in Vivo Inflammation Imaging

Triple-Standard Hypochlorite Quantitative Array Enabled by Precise Stokes Shift Modulation in D-π-A Chemodosimeters

The rational design of the D-π-A chemodosimeter with a significant Stokes shift is of great importance for enhancing the visualization of optical sensing signals. Here, three D-π-A fluorescent chemodosimeters with 2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene) malononitrile (TCF) as the electron-withdrawing group are synthesized by precisely modulating the electron-releasing strength. By decreasing the ability of electron release, the electrophilicity of the recognition site is increased by 1.449 kcal/mol, the Stokes shift of the chemodosimeter is improved to 201 nm, and the sensing mode changes from fluorescence quenching to ratiometric fluorescence and finally to fluorescence on. Furthermore, the three D-π-A fluorescent chemodosimeters display superior sensing performance toward ClO-, including low limits of detection (LOD, 37.0, 5.1, and 1.0 nM), rapid response (<5 s), and great selectivity in the presence of 16 kinds of interferents. Moreover, the practicality of the chemodosimeters is further validated by a portable triple-standard quantitative array detection platform, which can quantitatively detect ClO- solutions. The proposed design and modulation strategy for chemodosimeters can provide a new pathway for the sensitive and visualized identification of oxidants and other hazardous chemicals.

High-Photon-Harvesting Nanophotofertilizers for Plant Growth Multiregulation

Nanophotoresponsive technology has emerged as a promising way to enhance plant photosynthesis, but it faces limitations in light absorption and electron transfer efficiency. This study presents a photoresponsive nanosystem, LDNPs@Fe,Cu-CDs, combining lanthanide-doped nanoparticles (LDNPs) and Fe/Cu dual single-atom-doped carbon dots (CDs). Fabricated via hydrothermal synthesis, the nanosystem can regulate plant growth through light absorption, photothermal effects, photoelectron generation, and photocatalysis. Using a simple surface spraying method, the LDNPs@Fe,Cu-CDs can be absorbed by leaves and transported into N. benthamiana. LDNPs@Fe,Cu-CDs can harvest both near-infrared and ultraviolet light for photosynthesis and promote electron transfer in the photosynthetic chain by 33.2%. The nanosystem increased chlorophyll levels by 28.4% and enhanced photosynthesis by 67.5%. Additionally, it can alleviate the limitations of reactive oxygen species and cold environments, improving plant growth. The wet and dry weight of N. benthamiana were increased by 57.7% and 50.5%, respectively. LDNPs@Fe,Cu-CDs show great potential as a "nanophotofertilizer" for agricultural applications.

Luminescent Lanthanides in Biorelated Applications: From Molecules to Nanoparticles and Diagnostic Probes to Therapeutics

Lanthanides are particularly effective in their clinical applications in magnetic resonance imaging and diagnostic assays. They have open-shell 4f electrons that give rise to characteristic narrow, line-like emission which is unique from other fluorescent probes in biological systems. Lanthanide luminescence signal offers selection of detection pathways based on the choice of the ion from the visible to the near-infrared with long luminescence lifetimes that lend themselves to time-resolved measurements for optical multiplexing detection schemes and novel bioimaging applications. The delivery of lanthanide agents in cells allows localized bioresponsive activity for novel therapies. Detection in the near-infrared region of the spectrum coupled with technological advances in microscopies opens new avenues for deep-tissue imaging and surgical interventions. This review focuses on the different ways in which lanthanide luminescence can be exploited in nucleic acid and enzyme detection, anion recognition, cellular imaging, tissue imaging, and photoinduced therapeutic applications. We have focused on the hierarchy of designs that include luminescent lanthanides as probes in biology considering coordination complexes, multimetallic lanthanide systems to metal-organic frameworks and nanoparticles highlighting the different strategies in downshifting, and upconversion revealing some of the opportunities and challenges that offer potential for further development in the field.

Nanomaterials for light-mediated therapeutics in deep tissue

Light-mediated therapeutics, including photodynamic therapy, photothermal therapy and light-triggered drug delivery, have been widely studied due to their high specificity and effective therapy. However, conventional light-mediated therapies usually depend on the activation of light-sensitive molecules with UV or visible light, which have poor penetration in biological tissues. Over the past decade, efforts have been made to engineer nanosystems that can generate luminescence through excitation with near-infrared (NIR) light, ultrasound or X-ray. Certain nanosystems can even carry out light-mediated therapy through chemiluminescence, eliminating the need for external activation. Compared to UV or visible light, these 4 excitation modes penetrate more deeply into biological tissues, triggering light-mediated therapy in deeper tissues. In this review, we systematically report the design and mechanisms of different luminescent nanosystems excited by the 4 excitation sources, methods to enhance the generated luminescence, and recent applications of such nanosystems in deep tissue light-mediated therapeutics.

Nanocrystals for Deep-Tissue In Vivo Luminescence Imaging in the Near-Infrared Region

In vivo imaging technologies have emerged as a powerful tool for both fundamental research and clinical practice. In particular, luminescence imaging in the tissue-transparent near-infrared (NIR, 700-1700 nm) region offers tremendous potential for visualizing biological architectures and pathophysiological events in living subjects with deep tissue penetration and high imaging contrast owing to the reduced light-tissue interactions of absorption, scattering, and autofluorescence. The distinctive quantum effects of nanocrystals have been harnessed to achieve exceptional photophysical properties, establishing them as a promising category of luminescent probes. In this comprehensive review, the interactions between light and biological tissues, as well as the advantages of NIR light for in vivo luminescence imaging, are initially elaborated. Subsequently, we focus on achieving deep tissue penetration and improved imaging contrast by optimizing the performance of nanocrystal fluorophores. The ingenious design strategies of NIR nanocrystal probes are discussed, along with their respective biomedical applications in versatile in vivo luminescence imaging modalities. Finally, thought-provoking reflections on the challenges and prospects for future clinical translation of nanocrystal-based in vivo luminescence imaging in the NIR region are wisely provided.

LaVO4: Eu3+ nano-islands onto silica for achieving fluorescence enhancement and their detection of Fe3+ ions and anti-counterfeiting applications

Rare earth (RE) composite fluorescent materials are favored by researchers in the field of anti-counterfeiting and ion sensing due to their fascinating optical properties. Ultra-small RE fluorescent nanoparticles are anchored on inorganic carriers by a simple preparation method to improve luminous intensity and hydrophilicity, which has not been explored yet. Herein, LaVO4: Eu3+ nano-islands anchored on silica with high fluorescence intensity and easy formation of stable colloidal solution is designed. Through a simple and mild hydrothermal approach, ultra-small LaVO4: Eu3+ nano-islands are highly dispersed on the surface of hierarchical hollow silica sphere (HHSS) to expose more luminescent centers. Remarkably, the stable HHSS@LaVO4: Eu3+ colloidal solution displayed highly sensitive and selective sensor for Fe3+ ions. The "island-sea synergy" structure formed by the LaVO4: Eu3+ nano-islands and the surrounding silica surface makes HHSS@LaVO4: Eu3+ to be an outstanding sensor for the effective detection of iron ions in water. In addition, HHSS@LaVO4: Eu3+ phosphor exhibit unique properties for anti-counterfeiting and encryption applications. These findings provide a promising strategy for the carrierisation of RE luminescent materials to improve optical properties and enable broader applications.

pH-Responsive NIR-II phototheranostic agents for in situ tumor vascular monitoring and combined anti-vascular/photothermal therapy

Developing nanoplatforms integrating superior fluorescence imaging ability in second near-infrared (NIR-II) window and tumor microenvironment responsive multi-modal therapy holds great potential for real-time feedback of therapeutic efficacy and optimizing tumor inhibition. Herein, we developed a pH-sensitive pyrrolopyrrole aza-BODIPY-based amphiphilic molecule (PTG), which has a balanced NIR-II fluorescence brightness and photothermal effect. PTG is further co-assembled with a vascular disrupting agent (known as DMXAA) to prepare PTDG nanoparticles for combined anti-vascular/photothermal therapy and real-time monitoring of the tumor vascular disruption. Each PTG molecule has an active PT-3 core which is linked to two PEG chains via pH-sensitive ester bonds. The cleavage of ester bonds in the acidic tumor environment would tricker releases of DMXAA for anti-vascular therapy and further assemble PT-3 cores into micrometer particles for long term monitoring of the tumor progression. Furthermore, benefiting from the high brightness in the NIR-II region (119.61 M-1 cm-1) and long blood circulation time (t1/2 = 235.6 min) of PTDG nanoparticles, the tumor vascular disrupting process can be in situ visualized in real time during treatment. Overall, this study demonstrates a self-assembly strategy to build a pH-responsive NIR-II nanoplatform for real-time monitoring of tumor vascular disruption, long-term tracking tumor progression and combined anti-vascular/photothermal therapy.