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Developing high-efficient afterglow from metal-free organic molecules remains a formidable challenge due to the intrinsically spin-forbidden phosphorescence emission nature of organic afterglow, and only a few examples exhibit afterglow efficiency over 10%. Here, we demonstrate that the organic afterglow can be enhanced dramatically by thermally activated processes to release the excitons on the stabilized triplet state (T 1 * ) to the lowest triplet state (T 1 ) and to the singlet excited state (S 1 ) for spin-allowed emission. Designed in a twisted donor–acceptor architecture with small singlet-triplet splitting energy and shallow exciton trapping depth, the thermally activated organic afterglow shows an efficiency up to 45%. This afterglow is an extraordinary tri-mode emission at room temperature from the radiative decays of S 1 , T 1 , and T 1 * . With the highest afterglow efficiency reported so far, the tri-mode afterglow represents an important concept advance in designing high-efficient organic afterglow materials through facilitating thermally activated release of stabilized triplet excitons. The development of organic afterglow materials that do not contain heavy metals is of interest for biological applications. Here, the authors report on the development of a thermally activated organic molecule with tri-mode afterglow and an afterglow efficiency of up to 45%.

NIR-II fluorophores have shown great promise for biomedical applications with superior in vivo optical properties. To date, few small-molecule NIR-II fluorophores have been discovered with donor-acceptor-donor (D-A-D) or symmetrical structures, and upconversion-mitochondria-targeted NIR-II dyes have not been reported. Herein, we report development of D-A type thiopyrylium-based NIR-II fluorophores with frequency upconversion luminescence (FUCL) at ~580 nm upon excitation at ~850 nm. H4-PEG-PT can not only quickly and effectively image mitochondria in live or fixed osteosarcoma cells with subcellular resolution at 1 nM, but also efficiently convert optical energy into heat, achieving mitochondria-targeted photothermal cancer therapy without ROS effects. H4-PEG-PT has been further evaluated in vivo and exhibited strong tumor uptake, specific NIR-II signals with high spatial and temporal resolution, and remarkable NIR-II image-guided photothermal therapy. This report presents the first D-A type thiopyrylium NIR-II theranostics for synchronous upconversion-mitochondria-targeted cell imaging, in vivo NIR-II osteosarcoma imaging and excellent photothermal efficiency. Currently available mitochondria-targeted fluorescent dyes emit only one color in the visible or NIR-I and their applications are limited. Here, the authors develop upconversion mitochondria-targeted NIR-II fluorophores for synchronous upconversion-mitochondria-targeted cell imaging, in vivo NIR-II osteosarcoma imaging and photothermal efficiency

Photodynamic therapy (PDT) is a promising cancer treatment but has limitations due to its dependence on oxygen and high-power-density photoexcitation. Here, we report polymer-based organic photosensitizers (PSs) through rational PS skeleton design and precise side-chain engineering to generate •O 2 − and •OH under oxygen-free conditions using ultralow-power 808 nm photoexcitation for tumor-specific photodynamic ablation. The designed organic PS skeletons can generate electron-hole pairs to sensitize H 2 O into •O 2 − and •OH under oxygen-free conditions with 808 nm photoexcitation, achieving NIR-photoexcited and oxygen-independent •O 2 − and •OH production. Further, compared with commonly used alkyl side chains, glycol oligomer as the PS side chain mitigates electron-hole recombination and offers more H 2 O molecules around the electron-hole pairs generated from the hydrophobic PS skeletons, which can yield 4-fold stronger •O 2 − and •OH production, thus allowing an ultralow-power photoexcitation to yield high PDT effect. Finally, the feasibility of developing activatable PSs for tumor-specific photodynamic therapy in female mice is further demonstrated under 808 nm irradiation with an ultralow-power of 15 mW cm −2 . The study not only provides further insights into the PDT mechanism but also offers a general design guideline to develop an oxygen-independent organic PS using ultralow-power NIR photoexcitation for tumor-specific PDT. Conventional photodynamic therapy (PDT) is hindered by oxygen-dependent photosensitization pathways and high-power-density photoexcitation. Here, the authors develop polymer-based organic photosensitizers (PSs) through PS skeleton design and side-chain engineering to allow tumor-specific PDT under oxygen-free conditions using ultralow-power 808 nm photoexcitation.

Strong background interference signals from normal tissues have significantly compromised the sensitive fluorescence imaging of early disease tissues with exogenous probes in vivo, particularly for sensitive fluorescence imaging of early liver disease due to the liver’s significant uptake and accumulation of exogenous nanoprobes, coupled with high tissue autofluorescence and deep tissue depth. As a proof-of-concept study, we herein report a near-infrared-II (NIR-II, 1.0-1.7 μm) light-excited “off-on-off” NIR-II fluorescent probe (NDP). It has near-ideal zero initial probe fluorescence but can turn on its NIR-II fluorescence in liver cancer tissues and then turn off the fluorescence again upon migration from cancer to normal tissues to minimize background interference. Due to its low background, a blind study employing our probes could identify female mice with orthotopic liver tumors with 100% accuracy from mixed subjects of healthy and tumor mice, and implemented sensitive locating of early orthotopic liver tumors with sizes as small as 4 mm. Our NIR-II-excited “off-on-off” probe design concept not only provides a promising molecular design guideline for sensitive imaging of early liver cancer but also could be generalized for sensitive imaging of other early disease lesions. Background interference signals from normal tissues compromise the sensitive fluorescence imaging of early disease tissues with exogenous probes in vivo. Here, the authors report a Near-infrared-II excited ‘’off-on-off” fluorescent probe to focus on events occurring on the diffusion of the activated probes from cancer tissues to normal tissues for imaging of early orthotopic liver tumors.

Tumor response to radiotherapy or ferroptosis is closely related to hydroxyl radical (•OH) production. Noninvasive imaging of •OH fluctuation in tumors can allow early monitoring of response to therapy, but is challenging. Here, we report the optimization of a diene electrochromic material (1-Br-Et) as a •OH-responsive chromophore, and use it to develop a near-infrared ratiometric fluorescent and photoacoustic (FL/PA) bimodal probe for in vivo imaging of •OH. The probe displays a large FL ratio between 780 and 1113 nm (FL 780 /FL 1113 ), but a small PA ratio between 755 and 905 nm (PA 755 /PA 905 ). Oxidation of 1-Br-Et by •OH decreases the FL 780 /FL 1113 while concurrently increasing the PA 755 /PA 905 , allowing the reliable monitoring of •OH production in tumors undergoing erastin-induced ferroptosis or radiotherapy. The hydroxyl radical is generated during radiotherapy and ferroptosis and accurate imaging of this reactive oxygen species may permit the monitoring of response to therapy. Here, the authors develop a ratiometric probe for accurate imaging of hydroxyl radical generation in vivo.

Ultraviolet (UV) light, invisible to the human eye, possesses both benefits and risks. To harness its potential, UV photodetectors (PDs) have been engineered. These devices can convert UV photons into detectable signals, such as electrical impulses or visible light, enabling their application in diverse fields like environmental monitoring, healthcare, and aerospace. Wide bandgap semiconductors, with their high-efficiency UV light absorption and stable opto-electronic properties, stand out as ideal materials for UV PDs. This review comprehensively summarizes recent advancements in both traditional and emerging wide bandgap-based UV PDs, highlighting their roles in UV imaging, communication, and alarming. Moreover, it examines methods employed to enhance UV PD performance, delving into the advantages, challenges, and future research prospects in this area. By doing so, this review aims to spark innovation and guide the future development and application of UV PDs.

Fluorescence imaging in the second near-infrared window (NIR-II) allows visualization of deep anatomical features with an unprecedented degree of clarity. NIR-II fluorophores draw from a broad spectrum of materials spanning semiconducting nanomaterials to organic molecular dyes, yet unfortunately all water-soluble organic molecules with >1,000 nm emission suffer from low quantum yields that have limited temporal resolution and penetration depth. Here, we report tailoring the supramolecular assemblies of protein complexes with a sulfonated NIR-II organic dye (CH-4T) to produce a brilliant 110-fold increase in fluorescence, resulting in the highest quantum yield molecular fluorophore thus far. The bright molecular complex allowed for the fastest video-rate imaging in the second NIR window with ∼50-fold reduced exposure times at a fast 50 frames-per-second (FPS) capable of resolving mouse cardiac cycles. In addition, we demonstrate that the NIR-II molecular complexes are superior to clinically approved ICG for lymph node imaging deep within the mouse body. Near-infrared (NIR) fluorescence imaging >1,000 nm allows deep tissue imaging, but available organic dyes display poor brightness and temporal resolution. Here, the authors synthesize a NIR dye that, upon binding serum proteins, exhibits a 110-fold increase in intensity, giving an 11% quantum yield.

Minimizing the spectrum overlaps of energy transfer (ET) is necessary but not sufficient for achieving high-sensitivity film thermosensing. Herein we have designed two blue emitters of DBA-BPAc and Z-DBABH exhibiting blue and bluish-green emissions, respectively, to hybridize with the red-emitting Ir(MDQ)2(acac). Compared with Z-DBABH, DBA-BPAc shows a larger spectrum overlap of ET and a relatively smaller discrepancy in fluorescence thermal decay, while its emission spectrum displays a much smaller overlap with that of Ir(MDQ)2(acac). The dual minimization of spectrum overlap of ET and emissions results in its superior ratiometric film thermosensing of the DBA-BPAc film in wide-range and high-temperature regions. The DBA-BPAc/Ir(MDQ)2(acac) film exhibits a maximum relative sensitivity (Sr) of 3.36% °C−1 at 166 °C, exceeding 0.43% °C−1 in 50–265 °C. In comparison, the Z-DBABH/Ir(MDQ)2(acac) system displays a reliable but relatively lower performance, with a maximum Sr of 1.92% °C−1 (at 300 °C). The temperature resolution remains below 2.06 °C throughout the entire temperature range (20–300 °C), achieving a best value of 0.60 °C at 180 °C. Notably, both films display distinct naked-eye color transitions with temperature changes, enabling multi-level anti-counterfeiting applications. This work provides new insights for designing high-performance thermometers.

The development of smart theranostic systems with favourable biocompatibility, high loading efficiency, excellent circulation stability, potent anti-tumour activity, and multimodal diagnostic functionalities is of importance for future clinical application. The premature burst release and poor degradation kinetics indicative of polymer-based nanomedicines remain the major obstacles for clinical translation. Herein we prepare theranostic shell-crosslinked nanoparticles (SCNPs) using a β -cyclodextrin-based polyrotaxane (PDI-PCL- b -PEG-RGD⊃ β -CD-NH 2 ) to avoid premature drug leakage and achieve precisely controllable release, enhancing the maximum tolerated dose of the supramolecular nanomedicines. cRGDfK and perylene diimide are chosen as the stoppers of PDI-PCL- b -PEG-RGD⊃ β -CD-NH 2 , endowing the resultant SCNPs with excellent integrin targeting ability, photothermal effect, and photoacoustic capability. In vivo anti-tumour studies demonstrate that drug-loaded SCNPs completely eliminate the subcutaneous tumours without recurrence after a single-dose injection combining chemotherapy and photothermal therapy. These supramolecular nanomedicines also exhibit excellent anti-tumour performance against orthotopic breast cancer and prevent lung metastasis with negligible systemic toxicity. Multifunctional nanomedicine platforms are highly promising for anticancer therapy. Here, the authors design polyrotaxane-based theranostic nanoparticles that combine targeted drug delivery with photothermal behaviour to exhibit potent anti-tumour effects in vivo.

To improve bone metastases treatment efficacy, current strategies are focused on the integration of chemotherapy with phototheranostic. However, the success of phototheranostic approaches is hampered by the limited tissue penetration depth of near‐infrared‐I (NIR‐I) light (700–900 nm). In this study, a NIR‐II (1000–1700 nm) excitation phototheranostic (BTZ/Fe2+@BTF/ALD) is presented for NIR‐II fluorescence imaging and NIR‐II photoacoustic imaging‐guided NIR‐II photothermal therapy (PTT), chemotherapy, and chemodynamic therapy (CDT) of breast cancer bone metastases. This phototheranostic is developed by integrating a dopamine‐modified NIR‐II absorbing donor–acceptor–donor small molecule (BBT‐FT‐DA), the boronate anticancer drug bortezomib (BTZ), and Fe2+ ions, as CDT catalysts, into an amphiphilic PEGylated phospholipid modified with the bone‐targeting ligand alendronate. In acidic and hydrogen peroxide (H2O2) over expression tumor microenvironment, the boronate–catechol linkage is cleaved and BTZ and Fe2+ ions are released to initiate the Fenton reaction, that is, chemotherapy and CDT, respectively, are initialized. It is confirmed using the murine 4T1 bone metastasis model that BTZ/Fe2+@BTF/ALD significantly suppresses the progression of tumor cells in the bone tissue via a synergistic NIR‐II PTT/chemotherapy/CDT effect. Overall, this work provides fresh insights to guide the development of NIR‐II phototheranostics for breast cancer bone metastases. A near‐infrared‐II (NIR‐II) (1000–1700 nm) excitation phototheranostic (BTZ/Fe2+@BTF/ALD) is developed by integrating a dopamine‐modified NIR‐II absorbing small molecule, the anticancer drug bortezomib, and Fe2+ ions, into bone‐targeting ligand alendronate modified amphiphilic PEGylated phospholipid for NIR‐II fluorescence imaging and NIR‐II photoacoustic imaging‐guided NIR‐II photothermal, chemotherapy, and chemodynamic therapy of breast cancer bone metastases.