X-ray-activated nanosystems for theranostic applications

X-ray-Responsive Semiconducting Polymer siRNA Nanosystems for Orthotopic Glioma Treatment via Silencing the Immunosuppressive Signal

Gliomas are the most lethal types of adult brain tumors with a devastating prognosis, but many therapies have failed to exert good therapeutic benefits because of the extremely hypoxic and immunosuppressive tumor microenvironment. To address these challenges, we herein present a semiconducting polymer (SP)-based small interfering RNA (siRNA) nanosystem with the loading of oxygen self-supplying perfluorohexane (PFH) and conjugation of siRNA via a singlet oxygen (1O2)-cleavable linker. The nanosystems are further camouflaged with a macrophage membrane to obtain the final RM@SPN-siRNA. RM@SPN-siRNA displays an enhanced enrichment at the orthotopic glioma site due to surface cell membrane camouflaging. PFH provides sufficient oxygen to relieve tumor hypoxia, which boosts the production of 1O2 by the SP working as the radiosensitizer under external X-ray irradiation. The generated 1O2 destroys the 1O2-cleavable linker and disrupts the membrane structure to enable in situ siRNA release at the tumor site and subsequent activatable programmed death ligand-1 (PD-L1) silencing for tumor cells. As a consequence, an immunological effect is triggered to effectively inhibit tumor growths in an orthotopic glioma mouse model. This study offers an X-ray-responsive siRNA nanosystem for precise protein silencing and treatment of deep-seated orthotopic tumors.

Controlled Synthesis of Cs2NaYF6: Tb Nanoparticles for High-Resolution X-Ray Imaging and Molecular Detection

Rare-earth-doped fluoride nanoparticles (NPs), known for their tunable luminescence and high chemical stability, hold significant potential for applications in X-ray imaging and radiation dose monitoring. However, most research has primarily focused on lanthanide-doped NaLuF4 or NaYF4 nanosystems. In this work, Cs2NaYF6:Tb NPs with enhanced X-ray excited optical luminescence (XEOL) intensity were developed. Our results indicate that low oleic acid (OA) content and a high [Cs+]/[Na+] ratio favor the formation of pure cubic-phase Cs2NaYF6:Tb NPs. Cs2NaYF6:Tb NPs were successfully fabricated into thin films and employed as nanoscintillator screens for X-ray imaging, achieving a high spatial resolution of 20.0 Lp/mm. Beyond X-ray imaging applications, Cs2NaYF6:Tb NPs were also explored for spermine detection, demonstrating high sensitivity with a detection limit of 0.44 μM (under X-ray excitation) within a concentration range of 0-60 μM. These findings may contribute to the development of novel lanthanide-doped fluoride nanoscintillators for high-performance X-ray imaging and molecular sensing.

Amplifying X-ray-Induced Charge Transfer Facilitates Direct Sensitization of Photosensitizers in Radiotherapy

X-ray-induced photodynamic therapy offers substantial promise for treating deep-seated tumors, but it is still limited by highly inefficient energy transfer processes and the stringent requirements for scintillators with high luminescence quantum yield and significant singlet-triplet intersystem crossing ratios. Herein, we describe X-ray-induced electron-dynamic therapy (X-eDT), which obviates the need for intersystem crossing by exposing nonluminescent hafnium-silica nanoparticles to X-rays, to generate high-energy electrons that can sensitize lower-lying triplet states of various photosensitizers. Our approach strongly induced the production of singlet oxygen (6.18-fold) in vitro even at lower X-ray doses, and in mice it strongly inhibited the growth of xenografts derived from liver, breast, or colon cancer cell lines (CDX), and growth of patient-derived xenografts (PDX) of hepatocellular carcinoma. In these CDX preclinical systems, X-eDT was not only effective against the irradiated xenograft but also against untreated xenografts in the same animal, and these abscopal effects involved enhanced tumor infiltration by CD4+T cells, CD8+T cells, and IFN-γ-polarized M1 macrophages within the tumor microenvironment. X-eDT even stimulated the production of memory T cells that inhibited rechallenges after treatment. These findings suggest that X-eDT can be effective against primary and metastatic tumors as well as tumor recurrence, which makes it much more powerful than conventional X-PDT.

X-ray-Induced Photodegradation of Hydrogels by the Incorporation of X-ray-Activated Long Persistent Luminescent Nanoparticles

The development of on-demand degradable hydrogels remains an important challenge. Even though photodegradable hydrogels offer spatiotemporal control over degradation, it is difficult to use ultraviolet, visible, or near-infrared light as a tool for noninvasive triggering in vivo due to the poor tissue-penetration capacity. In contrast, X-ray irradiation can penetrate deep tissue and has virtually no penetration limitations for biological soft tissues. In this study, we propose an X-ray-photodegradation cascade system for hydrogel degradation by incorporating X-ray-activated persistent luminescence nanoparticles (X-PLNPs) into photodegradable hydrogels. A photodegradable 9,10-dialkoxyanthracene-based cross-linker was synthesized and used to prepare photodegradable hydrogels, of which the degradation behavior can be triggered by visible green light. Next, Tb3+-doped β-NaLuF4 was introduced as an X-PLNP that can convert X-rays into visible light centered at 544 nm. The afterglow can even be detected for 4 × 103 s after switching off the X-ray irradiation. The X-ray-induced green light emission was demonstrated to trigger photodegradation of the hydrogel. This proof-of-concept system for X-ray irradiation-induced on-demand hydrogel degradation was used to demonstrate X-ray-sensitive drug delivery inside a chicken breast as the in vitro tissue model. As this X-ray-induced cascade degradation of hydrogels can penetrate deep tissues, it is a promising platform for future in vivo applications requiring on-demand triggered hydrogel degradation, such as drug delivery or removal of hydrogel patches, hydrogel adhesives, or hydrogel tissue engineering scaffolds. It should, however, be noted that the hydrogel's X-ray and photoresponsiveness should be further improved to enable future in vivo use.

X-ray-activated nanoscintillators integrated with tumor-associated neutrophils polarization for improved radiotherapy in metastatic colorectal cancer

Radiotherapy, employing high-energy rays to precisely target and eradicate tumor cells, plays a pivotal role in the treatment of various malignancies. Despite its therapeutic potential, the effectiveness of radiotherapy is hindered by the tumor's inherent low radiosensitivity and the immunosuppressive microenvironment. Here we present an innovative approach that integrates peroxynitrite (ONOO-)-mediated radiosensitization with the tumor-associated neutrophils (TANs) polarization for the reversal of immunosuppressive tumor microenvironment (TME), greatly amplifying the potency of radiotherapy. Our design employs X-ray-activated lanthanide-doped scintillators (LNS) in tandem with photosensitive NO precursor to achieve in-situ ONOO- generation. Concurrently, the co-loaded TGF-β inhibitor SB525334, released from the LNS-RS nanoplatform in response to the overexpressed GSH in tumor site, promotes the reprogramming of TANs from N2 phenotype toward N1 phenotype, effectively transforming the tumor-promoting microenvironment into a tumor-inhibiting state. This 'one-two punch' therapy efficiently trigger a robust anti-tumor immune response and exert potent therapeutic effects in orthotopic colorectal cancer and melanoma mouse model. Meanwhile, it also significantly prevents liver metastasis and recurrence in metastatic colorectal cancer. The development of X-ray-controlled platforms capable of activating multiple therapeutic modalities may accelerate the clinical application of radiotherapy-based collaborative therapy.

Thermally activated delayed phosphorescence triggered by charge separation state carrier storage in an organic scintillator

Organic scintillators are among the most promising due to their inherent merits in terms of heavy metal-free constituents, synthesis designability, affordability of raw materials, and low usage costs. However, the limited X-ray excited luminescence (XEL) property of organic scintillators affects their application. To date, the main approaches for improving the XEL property of organic scintillators have focused on introducing heavy atoms to increase the absorbance of X-rays and establishing new luminescence pathways, such as thermally activated delayed fluorescence (TADF), to increase the exciton utilization efficiency. Even so, the XEL property of organic scintillators is not ideal compared with that of commercial inorganic scintillators. In this work, a highly stable charge separation (CS) state trap was introduced into the design of an organic scintillator. Combined with a unique thermally activated delayed phosphorescence (TADP) process, highly efficient capture and conversion of high-energy carriers are realized. As a result, the exciton generation efficiency dramatically increases, with an ultrahigh XEL intensity, and X-ray afterglow imaging at room temperature is achieved for the first time. This work provides a brand-new strategy for the design of high-performance organic scintillators.

Ultrabright and ultrafast afterglow imaging in vivo via nanoparticles made of trianthracene derivatives

Low sensitivity, photobleaching, high-power excitation and long acquisition times constrain the utility of afterglow luminescence. Here we report the design and imaging performance of nanoparticles made of electron-rich trianthracene derivatives that, on excitation by room light at ultralow power (58 μW cm-2), emit afterglow luminescence at ~500 times those of commonly used organic afterglow nanoparticles. The nanoparticles' ultrabright afterglow allowed for deep-tissue imaging (up to 6 cm), for ultrafast afterglow imaging (at short acquisition times down to 0.01 s) of naturally behaving mice with negligible photobleaching, even after re-excitation for over 15 cycles, and for the accurate visualization of subcutaneous and orthotopic tumours and of plaque in carotid arteries. We also show that an afterglow nanoparticle that is activated only in the presence of granzyme B allowed for the tracking of granzyme-B activity in the context of therapeutic monitoring. The high sensitivity and negligible photobleaching of the organic afterglow nanoparticles offer advantages for real-time in vivo monitoring of physiopathological processes.

Monitoring α/β Particles Using a Copper Cluster Scintillator Detector

High-energy radiation is widely used in medicine, industry, and scientific research. Meanwhile, the detection of environmental ionizing radiation is essential to ensure the safe use of high-energy radiation. Among radiation detectors, scintillator detectors offer multiple advantages, including simple structure, high sensitivity, excellent environmental adaptability, and a favorable performance-to-price ratio. However, the development of high-performance scintillators that can provide highly sensitive responses to environmental radiation, especially α/β particles, remains a challenge. In this work, a copper cluster (Cu4I4(DPPPy)2) with excellent water-oxygen stability is prepared using a simple one-pot method at room temperature. Cu4I4(DPPPy)2 not only exhibits excellent X-ray excited luminescence (XEL) under X-ray irradiation but also demonstrates a highly sensitive scintillation response to α/β particles. By integrating Cu4I4(DPPPy)2 with a photomultiplier tube (PMT) and nuclear electronics, an α/β surface contamination monitor is successfully developed. This monitor enables the sensitive detection of excessive α/β particles in real-world environments. The detection frequency and signal intensity of Cu4I4(DPPPy)2 significantly surpass those of commercial scintillator of YAP:Ce, BGO, PbWO4, and anthracene under identical conditions, highlighting the promising application of metal clusters in low-dose environmental radiation detection.

Bioengineered nanomaterials for dynamic diagnostics in vivo

In vivo diagnostics obtains real-time physiological information directly from the site of interest in a patient's body, providing more accurate disease diagnosis compared with ex vivo diagnostics. Particularly, in vivo dynamic diagnostics allows the continuous monitoring of physiological signals over a period of time, offering deeper insights into disease pathogenesis and progression. However, achieving in situ dynamic diagnostics in deep tissues presents challenges related to energy and signal penetration as well as dynamic monitoring. Bioengineered nanomaterials serve as an ideal platform for in vivo dynamic diagnostics, leveraging energy conversion and biofunctionalization to enable continuous acquisition of physiological information across temporal and spatial scales. In this review, with reference to the studies from the last five years, we summarize the fundamental components that are essential for dynamic diagnosis in vivo. Firstly, an input energy source with high tissue penetration is needed, such as near-infrared (NIR) light, X-rays, magnetic field and ultrasound. Secondly, a nanomaterial class that is responsive to such an energy source to provide a readable output signal is chosen. Thirdly, bioengineered nanoprobes are designed to exhibit spatial, temporal or spatiotemporal changes in the output signal. Finally, different methods are used to analyse the output signal of nanoprobes, such as detecting changes in optical, radiation, magnetic and ultrasound signals. This review also discusses the obstacles and potential solutions for advancing these bioengineered nanomaterials toward clinical translational applications.

Copper(I) Halide Complex Featuring Blue Thermally Activated Delayed Fluorescence and Aggregate Induced Emission for Efficient X-ray Scintillation and Imaging

Developing solution-processable and stable scintillators with high light yields, low detection limits and high imaging resolutions holds great significance for flexible X-ray imaging. However, attaining an optimal equilibrium among X-ray absorption capacity, exciton utilization efficiency, and decay lifetime of scintillators remains a substantial challenge. Here, a new Cu(I) halide complex was synthesized in a mild condition. It exhibits intense blue thermally activated delayed fluorescence (TADF), remarkable aggregation-induced emission (AIE) characteristic, as well as good water-oxygen stability and photochemical stability. Notably, the complex shows excellent radiation resistance and efficient radioluminescence (RL) with an ultra-low detection limit of 42.5 nGyairs-1. This superior scintillation performance can be attributed to the synergistic effect of effective X-ray absorption by the heavy Cu2I2 core, the high radiation-induced exciton utilization rate in TADF process, and the remarkable suppression of non-radiative transitions by the restriction of intramolecular motions in solid state. Furthermore, the favourable solution processability of the complex facilitates the successful fabrication of a flexible film, achieving high-quality X-ray imaging with a resolution of 17.3 lp mm-1. This work highlights the potential of hybrid Cu(I) halides with AIE-TADF effects for high-energy radiation detection and imaging, opening up new avenues for the exploration of cost-effective and high-performance scintillators.

In Situ and Real-Time Multi-Modality Imaging Guided Orderly Triple-Therapy of Tumors with a Multifunctional Nanodrug

Effective integration of different therapeutic methods is a promising way to improve the overall efficacy of tumor therapy, which needs to be guided by in situ and real-time monitoring of each therapeutic process. Here a multifunctional AuNR@SiO2@MnO2@DNA prodrugs (ASMD) nanodrug is designed for orderly photothermal therapy (PTT)/chemodynamic therapy (CDT)/gene therapy (GT) triple-therapy of tumors, which can be guided by the in situ and real-time photoacoustic (PA)/magnetic resonance (MR)/fluorescence (FL) multi-modality imaging. The gold nanorod in ASMD can generate a PA signal and perform PTT. The MnO2 in ASMD can respond to the glutathione inside tumor cells to release Mn2+, which can generate MR signal and perform CDT by catalyzing the degradation of intracellular H2O2 to generate ·OH. The DNA prodrugs can perform a cascade response in the presence of the released Mn2+ and the intracellular microRNA 21, which can turn on the quenched FL signal and release small-interfering RNA and antisense oligonucleotide to perform GT. Guiding by the in situ and real-time PA/MR/FL multi-modality imaging of each therapeutic process, an orderly PTT/CDT/GT triple-therapy of tumors is established, which provides a significant and promising strategy to develop more efficient and practical therapeutic programs for tumors.

Unnatural Triggers Converted From Tetrazine-Attached Sialic Acid for Activation of Optoacoustic Imaging-Guided Cancer Theranostics

Constructing chemical groups on cell membranes through metabolic glycoengineering of unnatural sugars is an effective means to solve the issue of insufficient or even lack of targets in cancer theranostics. Herein, we address the limitations by developing a tetrazine precursor (SiaTz) based on a nonO-acetylated sialic acid scaffold and then utilizing it to create unnatural tetrazine triggers on the surface of cancer cells. SiaTz exhibits a good balance between the stability and reaction kinetics under physiological conditions and can be efficiently converted into corresponding tetrazine trigger through bypassing several size-limiting steps in metabolic glycoengineering process. We also prepare a proof-of-concept theranostic combination of a trans-cyclooctene derivative (CyTCO) and a thermal-sensitive drug 2,2'-azobis[2-(2-imidazolin-2-yl) propane]-dihydrochloride (AIPH) to verify the activation function of tetrazine triggers in theranostics of orthotopic and metastatic tumors. In the presence of tetrazine triggers, CyTCO can be activated via bio-orthogonal reaction to induce optoacoustic signal enhancement, enabling high-contrast diagnostic imaging and precise tumor localization to guide subsequent treatments. Tetrazine trigger-activated CyTCO displays high photo-to-heat conversion efficiency, which can cause an obvious increase in temperature under laser irradiation and then initiate AIPH decomposition to produce toxic radicals for combined therapy.

Probing structural defects and X-ray induced persistent luminescence mechanisms on rare earth-doped strontium sulfide materials

Persistent luminescence is related to the existence of point defects in the crystal structure, which can be induced by the insertion of dopant ions to create trap levels for charge carriers. Strontium sulfide (SrS) is a promising host for X-ray activated phosphors due to its high luminescence yield and X-ray absorption efficiency. While the mechanisms of UV- and visible light-induced luminescence in rare-earth doped SrS have been previously explored, this work focuses on understanding X-ray induced mechanisms using synchrotron radiation techniques. Extended X-ray absorption fine structure (EXAFS) analysis suggested that rare-earth ions incorporate into the SrS lattice primarily as substitutional defects, with structural distortions depending on the differences in ionic radii between Sr2+ and RE2+/3+. X-ray absorption near edge structure (XANES) spectra revealed the mixed-valence nature of Ce in SrS:Ce and SrS:Eu,Ce materials, and also that X-ray irradiation triggers complex charge transfer processes. The X-ray excited optical luminescence (XEOL) results showed that co-doped samples exhibited longer persistent luminescence decay times than their single-doped counterparts due to the increased number of defects. These findings provide new insights into the interplay between crystal defects and persistent luminescence in X-ray-activated phosphors, contributing to the design of more efficient materials for applications such as medical imaging, optical information storage, and industrial sensing.

A Salidroside-Based Radiosensitizer Regulates the Nrf2/ROS Pathway for X-Ray Activated Synergistic Cancer Precise Therapy

The hypoxic microenvironment and radioresistance of tumor cells, as well as the delay in efficacy evaluation, significantly limit the effect of clinical radiotherapy. Therefore, developing effective radiosensitizers with monitoring of tumor response is of great significance for precise radiotherapy. Herein, a novel radiosensitizer (term as: SCuFs) is developed, consisting of traditional Chinese medicine (TCM) compounds salidroside, Cu2+, and hydroxyl radical (•OH) activated second near-infrared window fluorescence (NIR-II FL) molecules, which make the radiosensitization effect and boosted chemodynamic therapy (CDT) efficacy. The overexpressed glutathione in the tumor induces the SCuFs dissociation, allowing deep penetration of the drug to the whole tumor region. After X-ray irradiation, salidroside inhibits the Nuclear factor erythroid 2-like 2 (Nrf2)protein expression and blocks cells in the G2/M phase with the highest radiosensitivity, which amplifies the reactive oxygen species (ROS) generation to exacerbate DNA damage, thus achieving radiosensitization. Meanwhile, the upregulated ROS provides sufficient chemical fuel for Cu+-mediated CDT to produce more •OH. NIR-II FL imaging can monitor the •OH changes during the therapy process, confirming the radiosensitization effect and CDT process related to •OH. This study not only achieves effective radiosensitization and cascaded ROS-mediated CDT efficacy, but also provides a useful tool for monitoring therapeutic efficacy, showing great prospects for clinical application.

Fabrication Strategies of Mn2+-Based Scintillation Screens for X-Ray Detection and Imaging

Scintillators play a pivotal role in multiple fields such as medical imaging, radioactive contaminant detection, non-destructive testing, high-energy physics and homeland security. However, the traditional inorganic scintillators are faced with the shortcomings of high fabrication cost and low light yield. In recent years, organic-inorganic hybrid metal halides have become the promising alternatives for their excellent luminescence properties, favorable air and irradiation stability, and low-cost preparation. Among them, organic-inorganic hybrid Mn(II) halides (OIMnHs) have attracted wide attention due to their particular flexible molecular structure design, easy synthesis and low toxicity. This minireview summarizes the latest progress in high performance Mn2+-Based scintillation screens. Herein, the scintillation mechanism of OIMnHs scintillators is firstly discussed. Then, the different synthesis methods of OIMnHs scintillators are briefly described, including solvent diffusion, cooling crystallization, evaporative crystallization and solid-state mechanochemical synthesis. After that, the recent strategies of OIMnHs for forming scintillation screens applying to X-ray imaging are emphatically reviewed, which are growing large single crystals, fabricating to glass or ceramic and blending with polymers. The fabrication progress and applications of OIMnHs-based scintillation screens were introduced and the structure-property relationship of these screens was discussed. Finally, the challenges of this new scintillator material are summarized, and the potential research directions for future exploration are proposed.

PhotoChem Interplays: Lighting the Way for Drug Delivery and Diagnosis

Light, a non-invasive tool integrated with cutting-edge nanotechnologies, has driven transformative advancements in imaging-based diagnosis and drug delivery for cancer and bacterial treatments. This review discusses recent progress in these areas, beginning with emerging imaging technologies. Unlike traditional photosensors activated by visible light, alternative energy sources such as near-infrared (NIR) light, X-rays, and ultrasound have been extensively investigated to activate various photosensors, achieving high sensitivity, wavelength versatility, and spatial resolution for deep-tissue imaging. Moreover, to address challenges like tissue autofluorescence in real-time fluorescence imaging, afterglow luminescent nanoparticles are being developed by integrating these alternative energy sources for real-time imaging and sensing in deep tissue for precise cancer diagnosis and treatment beyond superficial tissues. In addition to deep tissue imaging, light-responsive nanomedicines are revolutionizing anticancer and antimicrobial phototherapy by enabling spatially and temporally controlled drug release. These smart nanoparticles are engineered to release therapeutic cargo at target sites in response to microenvironmental cues specific to tumors or infections. In anticancer phototherapy, these nanoparticles facilitate controlled drug release via photoisomerization, photothermal, and photodynamic processes. To enhance circulation time and specific targeting, biomimetic nanoparticles, which mimic natural anti-tumor responses by our body, have attracted increasing attention. In antimicrobial phototherapy, research has been focused on the chemical modification of the photosensitizer to enable targeted drug delivery. An intriguing strategy has recently emerged involving the development of "pro-photosensitizers" that are specifically activated within bacterial cells upon light irradiation, offering a high margin of safety. These advancements leverage photochemical reactions and nanotechnology to enhance precision therapy and diagnosis in addressing critical health challenges.

One-Dose Bioorthogonal Gadolinium Nanoprobes for Prolonged Radiosensitization of Tumor

Developing effective radiotherapy is impeded by tumor radioresistance, imprecise treatment, and the need for accurate imaging. Herein, a multifunctional gadolinium-based nanoprobe (GBD) is presented, integrating bioorthogonal click chemistry and theranostics to enhance tumor retention, magnetic resonance imaging (MRI) contrast, and radiosensitivity. GBD synthesis involved biomimetic mineralization of bovine serum albumin (BSA) with gadolinium ions to form nanoparticles (GB), followed by conjugation with dibenzocyclooctyne (DBCO). The optimized GBD exhibited an elevated longitudinal relaxivity (r1) of 25.54 mM-1 s-1, which represented a 6.7-fold enhancement compared to the clinical MRI contrast agent magnevist (Gd-DTPA, 3.81 mM-1 s-1). Notably, the application of bioorthogonal click chemistry enhanced the affinity and retention of GBD within tumor cells modified to express azide as an artificial receptor. This novel strategy enhanced tumor retention up to 16 days postinjection, outperforming DBCO-modified small molecule gadolinium (Gd-DBCO) with less than 1-day retention. Such prolonged retention facilitated continuous radiosensitization throughout the radiotherapy course, negating the need for multiple injections, and substantially boosted the effectiveness of radiotherapy. This study demonstrates the transformative potential of combining bioorthogonal click chemistry with nanotechnology in radiotherapy, offering a precise tumor targeting platform, real-time monitoring, and improved treatment outcomes.

Evolution of nMOFs in photodynamic therapy: from porphyrins to chlorins and bacteriochlorins for better efficacy

Photodynamic therapy (PDT) has gained significant attention due to its non-invasive nature, low cost, and ease of operation. Nanoscale metal-organic frameworks (nMOFs) incorporating porphyrins, chlorins, and bacteriochlorins have emerged as one of the most prominent photoactive materials for tumor PDT. These nMOFs could enhance the water solubility, stability and loading efficiency of photosensitizers (PSs). Their highly ordered porous structure facilitates O2 diffusion and enhances the generation of 1O2 from hydrophobic porphyrins, chlorins, and bacteriochlorins, thereby improving their efficacy of phototherapy. This review provides insights into the PDT effects of nMOFs derived from porphyrins, chlorins, and bacteriochlorins. It overviews the design strategies, types of reactive oxygen species (ROS), ROS generation efficiency, and the unique biological processes involved in inhibiting tumor cell proliferation, focusing on the mechanism by which molecular structure leads to enhanced photochemical properties. Finally, the review highlights the new possibilities offered by porphyrins, chlorins, and bacteriochlorins-based nMOFs for tumor PDT, emphasizing how optimized design can further improve the bioapplication of porphyrin derivatives represented PSs. With ongoing research and technological advancements, we anticipate that this review will garner increased attention from scientific researchers toward porphyrin-based nMOFs, thereby elevating their potential as a prominent approach in the treatment of malignant tumors.

Recent Progress in Radiosensitive Nanomaterials for Radiotherapy-Triggered Drug Release

Benefiting from the unique properties of ionizing radiation, such as high tissue penetration, spatiotemporal resolution, and clinical relevance compared with other external stimuli, radiotherapy-induced drug release strategies are showing great promise in developing effective and personalized cancer treatments. However, the requirement of high doses of X-ray irradiation to break chemical bonds for drug release limits the application of radiotherapy-induced prodrug activation in clinics. Recent advances in nanomaterials offer a promising approach for radiotherapy sensitization as well as integrating multiple modalities for improved therapy outcomes. In particular, the catalytic radiosensitization that utilizes electrons and energy generated by nanomaterials upon X-ray irradiation has demonstrated excellent potential for enhanced radiotherapy. In this Review, we summarize the design principles of X-ray-responsive chemical bonds for controlled drug release, strategies for catalytic radiosensitization, and recent progress of X-ray-responsive nanoradiosensitizers for enhanced radiotherapy by integration with chemotherapy, chemodynamic therapy, photodynamic therapy, photothermal therapy, gas therapy, and immunotherapy. Finally, we discuss the challenges of X-ray-responsive nanoradiosensitizers heading toward possible clinical translation. We expect that emerging strategies based on radiotherapy-triggered drug release will facilitate a frontier in accurate and effective cancer therapy in the near future.

MnO2@CeOx-GAMP radiosensitizer with oxygen vacancies depended mimicking enzyme-like activities for radiosensitization-mediated STING pathway activation

Activation of the stimulator of interferon genes (STING) pathway by radiotherapy (RT) has a significant effect on eliciting antitumor immune responses. The generation of hydroxyl radical (·OH) storm and the sensitization of STING-relative catalytic reactions could improve radiosensitization-mediated STING activation. Herein, multi-functional radiosensitizer with oxygen vacancies depended mimicking enzyme-like activities was fabricated to produce more dsDNA which benefits intracellular 2', 3'-cyclic GMP-AMP (cGAMP) generation, together with introducing exogenous cGAMP to activate immune response. MnO2@CeOx nanozymes present enhanced superoxide dismutase (SOD)-like and peroxidase (POD)-like activities due to induced oxygen vacancies accelerate the redox cycles from Ce4+ to Ce3+ via intermetallic charge transfer. CeOx shells not only serve as radiosensitizer, but also provide the conjugation site for AMP/GMP to form MnO2@CeOx-GAMP (MCG). Upon X-ray irradiation, MCG with SOD-like activity facilitates the conversion of superoxide anions generated by Ce-sensitization into H2O2 within tumor microenvironment (TME). The downstream POD-like activity catalyzes the elevated H2O2 into a profusion of ·OH for producing more damage DNA fragments. TME-responsive decomposed MCG could supply exogenous cGAMP, meanwhile the releasing Mn2+ improve the sensitivity of cyclic GMP-AMP synthase to dsDNA for producing more cGAMP, resulting in the promotion of STING pathway activation.

Transferrin-Based Bismuth Nanoparticles for Radiotherapy with Immunomodulation Against Orthotopic Glioma

Modern radiotherapy frequently employs radiosensitizers for radiation dose deposition and triggers an immunomodulatory effect to enhance tumor destruction. However, developing glioma-targeted sensitizers remains challenging due to the blood-brain barrier (BBB) and multicomponent instability. This study aims to green-synthesize transferrin-bismuth nanoparticles (TBNPs) as biosafe radiosensitizers to enhance X-ray absorption by tumors and stimulate the immune response for glioma therapy. The proposed protein-based strategy provides TBNPs with BBB-crossing ability and prevents off-target toxicity. Cellular experiments following 4 Gy of X-ray irradiation reveal that TBNPs increase DNA damage in glioma cells and trigger immunomodulation, thereby inducing immunogenic cell death. Furthermore, TBNPs effectively inhibit tumor growth through synergistic radiotherapy and immunotherapy in an orthotopic glioma mouse model. The findings highlight TBNPs as promising radiosensitizers for effective and biosafe radiotherapy with immunomodulation.

High-Performance Oxide Crystal BaTeW2O9 X-ray Detector with High Stability, Low Detection Limit, and Ultralow Dark Current Drift

X-ray detection materials and devices have received widespread attention due to their irreplaceable role in the medical, industrial, and military fields. In this paper, BaTeW2O9 (BTW) crystal containing lone pairs of electrons with large atomic numbers and high density is reported as a new type of oxide crystal X-ray detection material. The anisotropic X-ray detection performance of the BTW single crystal (SC) is systematically studied. At 120 keV hard X-ray photon energy, the BTW SC X-ray detectors along the crystallographic a-, b-, and c-axes directions achieved high sensitivities of 371, 404, and 368 μC Gyair-1 cm-2 respectively. More importantly, no dark current drift phenomenon was observed in the BTW SC X-ray detectors. The dark current drifts along the crystallographic a-, b-, and c-axes directions are as low as 7.81 × 10-9, 8.61 × 10-9, and 7.71 × 10-9 nA cm-1 s-1 V-1, respectively. In addition, the BTW SC X-ray detector has an ultralow detection limit of 21.9 nGyair s-1. Our research provides a new X-ray detection material with potential application value and a new material design strategy for the field of radiation detection.

Study of Construction of Innovative Barite/Waterborne Polyurethane/Low-Density Polyethylene Composites for Enhanced X-Ray Shielding Performance

X-rays' high-energy nature poses risks to human health. Traditional X-ray shielding materials often contain toxic lead and have drawbacks like bulkiness and rigidity. Consequently, there is an increasing need to develop lightweight, non-toxic, flexible, and efficient shielding materials. In this study, we modified barite with waterborne polyurethane (WPU) and systematically investigated the effects of WPU on barite's properties. The modification with WPU not only reduced the tendency of barite (B) to agglomerate but also enhanced its compatibility with polymers, thereby significantly improving the mechanical properties of LDPE/WPU-B composites. Compared to unmodified barite in LDPE/B composites, the tensile and flexural modulus of the LDPE/WPU-B composites increased by 22.31% and 29.64%, respectively. With 20% WPU-modified barite, the radiation shielding efficiency increased by 5%. When the WPU-B content reached 40%, the shielding efficiency of the LDPE/WPU-B composite exceeded 90% for tube voltages ranging from 60 kV to 120 kV, achieving a lead equivalent of 0.38 mmPb at 100 kV. This novel LDPE/WPU-B composite has great potential for low-dose radiation shielding applications.

Tumor-Targeted Catalytic Immunotherapy

Cancer immunotherapy holds significant promise for improving cancer treatment efficacy; however, the low response rate remains a considerable challenge. To overcome this limitation, advanced catalytic materials offer potential in augmenting catalytic immunotherapy by modulating the immunosuppressive tumor microenvironment (TME) through precise biochemical reactions. Achieving optimal targeting precision and therapeutic efficacy necessitates a thorough understanding of the properties and underlying mechanisms of tumor-targeted catalytic materials. This review provides a comprehensive and systematic overview of recent advancements in tumor-targeted catalytic materials and their critical role in enhancing catalytic immunotherapy. It highlights the types of catalytic reactions, the construction strategies of catalytic materials, and their fundamental mechanisms for tumor targeting, including passive, bioactive, stimuli-responsive, and biomimetic targeting approaches. Furthermore, this review outlines various tumor-specific targeting strategies, encompassing tumor tissue, tumor cell, exogenous stimuli-responsive, TME-responsive, and cellular TME targeting strategies. Finally, the discussion addresses the challenges and future perspectives for transitioning catalytic materials into clinical applications, offering insights that pave the way for next-generation cancer therapies and provide substantial benefits to patients in clinical settings.

Metabolizable alloy clusters assemble nanoinhibitor for enhanced radiotherapy of tumor by hypoxia alleviation and intracellular PD-L1 restraint

BACKGROUND

Cancer radiotherapy (RT) still has limited clinical success because of the obstacles including radioresistance of hypoxic tumors, high-dose X-ray-induced damage to adjacent healthy tissue, and DNA-damage repair by intracellular PD-L1 in tumor.

RESULTS

Therefore, to overcome these obstacles multifunctional core-shell BMS@Pt2Au4 nanoparticles (NPs) are prepared using nanoprecipitation followed by electrostatic assembly. Pt2Au4 clusters are released from BMS@Pt2Au4 NPs to alleviate tumor hypoxia by catalyzing the decomposition of endogenous H2O2 to generate O2 as well as by enhancing X-ray deposition at the tumor site, which thereby reduce the required X-ray dose. The released BMS-202 molecules simultaneously blockade PD-L1 on and in tumor cells, causing the activation of effector T cells and the inhibition of DNA-damage repair. Consequently, radiotherapy based on BMS@Pt2Au4 NPs enhance the expression of calreticulin on cancer cells, transposition of HMGB1 from the nucleus to the cytoplasm, generation of reactive oxygen species (ROS), DNA breakage and apoptosis of cancer cells in vitro. The tumor inhibition rate reached 92.5% under three cycles of 1-Gy X-ray irradiation in vivo.

CONCLUSION

In conclusion, the therapeutic outcome supports the high-efficiency of radiotherapy based on BMS@Pt2Au4 NPs in hypoxic tumors expressing PD-L1.

A new era of cancer phototherapy: mechanisms and applications

The past decades have witnessed great strides in phototherapy as an experimental option or regulation-approved treatment in numerous cancer indications. Of particular interest is nanoscale photosensitizer-based phototherapy, which has been established as a prominent candidate for advanced tumor treatment by virtue of its high efficacy and safety. Despite considerable research progress on materials, methods and devices in nanoscale photosensitizing agent-based phototherapy, their mechanisms of action are not always clear, which impedes their practical application in cancer treatment. Hence, from a new perspective, this review elaborates the working mechanisms, involving impairment and moderation effects, of diverse phototherapies on cells, organelles, organs, and tissues. Furthermore, the most current available phototherapy modalities are categorized as photodynamic, photothermal, photo-immune, photo-gas, and radio therapies in this review. A comprehensive understanding of the inferiority and superiority of various phototherapies will facilitate the advent of a new era of cancer phototherapy.

Tumor-specific delivery of clickable inhibitor for PD-L1 degradation and mitigating resistance of radioimmunotherapy

Achieving selective and durable inhibition of programmed death ligand 1 (PD-L1) in tumors for T cell activation remains a major challenge in immune checkpoint blockade therapy. We herein presented a set of clickable inhibitors for spatially confined PD-L1 degradation and radioimmunotherapy of cancer. Using metabolic glycan engineering click bioorthogonal chemistry, PD-L1 expressed on tumor cell membranes was labeled with highly active azide groups. This enables covalently binding of the clickable inhibitor with PD-L1 and subsequent PD-L1 degradation. A pH-activatable nanoparticle responding to extracellular acidic pH of tumor was subsequently used to deliver the clickable PD-L1 inhibitor into extracellular tumor microenvironment for depleting PD-L1 on the surface of tumor cell and macrophage membranes in vivo. We further demonstrated that a combination of the clickable PD-L1 inhibitor with radiotherapy (RT) eradicated the established tumor by inhibiting RT-up-regulated PD-L1 in the tumor tissue. Therefore, selective PD-L1 blockade in tumors via the clickable PD-L1 inhibitor offers a versatile approach to promote cancer immunotherapy.

Light/X-ray/ultrasound activated delayed photon emission of organic molecular probes for optical imaging: mechanisms, design strategies, and biomedical applications

Conventional optical imaging, particularly fluorescence imaging, often encounters significant background noise due to tissue autofluorescence under real-time light excitation. To address this issue, a novel optical imaging strategy that captures optical signals after light excitation has been developed. This approach relies on molecular probes designed to store photoenergy and release it gradually as photons, resulting in delayed photon emission that minimizes background noise during signal acquisition. These molecular probes undergo various photophysical processes to facilitate delayed photon emission, including (1) charge separation and recombination, (2) generation, stabilization, and conversion of the triplet excitons, and (3) generation and decomposition of chemical traps. Another challenge in optical imaging is the limited tissue penetration depth of light, which severely restricts the efficiency of energy delivery, leading to a reduced penetration depth for delayed photon emission. In contrast, X-ray and ultrasound serve as deep-tissue energy sources that facilitate the conversion of high-energy photons or mechanical waves into the potential energy of excitons or the chemical energy of intermediates. This review highlights recent advancements in organic molecular probes designed for delayed photon emission using various energy sources. We discuss distinct mechanisms, and molecular design strategies, and offer insights into the future development of organic molecular probes for enhanced delayed photon emission.

Morphofunctional Features of Glomeruli and Nephrons After Exposure to Electrons at Different Doses: Oxidative Stress, Inflammation, Apoptosis

Kidney disease has emerged as a significant global health issue, projected to become the fifth-leading cause of years of life lost by 2040. The kidneys, being highly radiosensitive, are vulnerable to damage from various forms of radiation, including gamma (γ) and X-rays. However, the effects of electron radiation on renal tissues remain poorly understood. Given the localized energy deposition of electron beams, this study seeks to investigate the dose-dependent morphological and molecular changes in the kidneys following electron irradiation, aiming to address the gap in knowledge regarding its impact on renal structures. The primary aim of this study is to conduct a detailed morphological and molecular analysis of the kidneys following localized electron irradiation at different doses, to better understand the dose-dependent effects on renal tissue structure and function in an experimental model. Male Wistar rats (n = 75) were divided into five groups, including a control group and four experimental groups receiving 2, 4, 6, or 8 Gray (Gy) of localized electron irradiation to the kidneys. Biochemical markers of inflammation (interleukin-1 beta [IL-1β], interleukin-6 [IL-6], interleukin-10 [IL-10], tumor necrosis factor-alpha [TNF-α]) and oxidative stress (malondialdehyde [MDA], superoxide dismutase [SOD], glutathione [GSH]) were measured, and morphological changes were assessed using histological and immunohistochemical techniques (TUNEL assay, caspase-3). The study revealed a significant dose-dependent increase in oxidative stress, inflammation, and renal tissue damage. Higher doses of irradiation resulted in increased apoptosis, early stages of fibrosis (at high doses), and morphological changes in renal tissue. This study highlights the dose-dependent effects of electrons on renal structures, emphasizing the need for careful consideration of the dosage in clinical use to minimize adverse effects on renal function.

Polypyrrole/iron-glycol chitosan nanozymes mediate M1 macrophages to enhance the X-ray-triggered photodynamic therapy for bladder cancer by promoting antitumor immunity

X-ray Photodynamic Therapy (XPDT) is an emerging, deeply penetrating, and non-invasive tumor treatment that stimulates robust antitumor immune responses. However, its efficacy is often limited by low therapeutic delivery and immunosuppressant within the tumor microenvironment. This challenge can potentially be addressed by utilizing X-ray responsive iron-glycol chitosan-polypyrrole nanozymes (GCS-I-PPy NZs), which activate M1 macrophages. These nanozymes increase tumor infiltration and enhance the macrophages' intrinsic immune response and their ability to stimulate adaptive immunity. Authors have designed biocompatible, photosensitizer-containing GCS-I-PPy NZs using oxidation/reduction reactions. These nanozymes were internalized by M1 macrophages to form RAW-GCS-I-PPy NZs. Authors' results demonstrated that these engineered macrophages effectively delivered the nanozymes with potentially high tumor accumulation. Within the tumor microenvironment, the accumulated GCS-I-PPy NZs underwent X-ray irradiation, generating reactive oxygen species (ROS). This ROS augmentation significantly enhanced the therapeutic effect of XPDT and synergistically promoted T cell infiltration into the tumor. These findings suggest that nano-engineered M1 macrophages can effectively boost the immune effects of XPDT, providing a promising strategy for enhancing cancer immunotherapy. The ability of GCS-I-PPy NZs to mediate M1 macrophage activation and increase tumor infiltration highlights their potential in overcoming the limitations of current XPDT approaches and improving therapeutic outcomes in melanoma and other cancers.

The wonders of X-PDT: an advance route to cancer theranostics

Global mortality data indicates cancer as the second-leading cause of death worldwide. Therefore, there's a pressing need to innovate effective treatments to address this significant medical and societal challenge. In recent years, X-ray-induced photodynamic therapy (X-PDT) has emerged as a promising advancement, revolutionizing traditional photodynamic therapy (PDT) for deeply entrenched malignancies by harnessing penetrating X-rays as external stimuli. Recent developments in X-ray photodynamic therapy have shown a trend toward minimizing radiation doses to remarkably low levels after the proof-of-concept demonstration. Early detection and real-time monitoring are crucial aspects of effective cancer treatment. Sophisticated X-ray imaging techniques have been enhanced by the introduction of X-ray luminescence nano-agents, alongside contrast nanomaterials based on X-ray attenuation. X-ray luminescence-based in vivo imaging offers excellent detection sensitivity and superior image quality in deep tissues at a reasonable cost, due to unhindered penetration and unimpeded auto-fluorescence of X-rays. This review emphasizes the significance of X-ray responsive theranostics, exploring their mechanism of action, feasibility, biocompatibility, and promising prospects in imaging-guided therapy for deep-seated tumors. Additionally, it discusses promising applications of X-PDT in treating breast cancer, liver cancer, lung cancer, skin cancer, and colorectal cancer.

X-ray/γ-ray/Ultrasound-Activated Persistent Luminescence Phosphors for Deep Tissue Bioimaging and Therapy

Persistent luminescence phosphors (PLPs) can remain luminescent after excitation ceases and have been widely explored in bioimaging and therapy since 2007. In bioimaging, PLPs can efficiently avoid tissue autofluorescence and light scattering interference by collecting persistent luminescence signals after the end of excitation. Outstanding signal-to-background ratios, high sensitivity, and resolution have been achieved in bioimaging with PLPs. In therapy, PLPs can continuously produce therapeutic molecules such as reactive oxygen species after removing excitation sources, which realizes sustained therapeutic activity after a single dose of light stimulation. However, most PLPs are activated by ultraviolet or visible light, which makes it difficult to reactivate the PLPs in vivo, particularly in deep tissues. In recent years, excitation sources with deep tissue penetration have been explored to activate PLPs, including X-ray, γ-ray, and ultrasound. Researchers found that various inorganic and organic PLPs can be activated by X-ray, γ-ray, and ultrasound, making these PLPs valuable in the imaging and therapy of deep-seated tumors. These X-ray/γ-ray/ultrasound-activated PLPs have not been systematically introduced in previous reviews. In this review, we summarize the recently developed inorganic and organic PLPs that can be activated by X-ray, γ-ray, and ultrasound to produce persistent luminescence. The biomedical applications of these PLPs in deep-tissue bioimaging and therapy are also discussed. This review can provide instructions for the design of PLPs with deep-tissue-renewable persistent luminescence and further promote the applications of PLPs in phototheranostics, noninvasive biosensing devices, and energy harvesting.

Theoretical analysis of electron transport in perovskite thin films

Inherent disorder in perovskite films has been suggested as a factor that improves exciton separation. At the same time, the disorder can potentially disrupt electron flow, deteriorating device performance. In this paper, we study the role of disorder in electron transport in perovskite films using kinetic Monte Carlo simulations. The effect of temperature on the conductivity of the system is studied. We find that at room temperature, where most solar cells operate, the effect of disorder on the conductivity is minimal. At lower temperatures, current flows along specific paths in the film. In contrast, the ability of carriers to sample all sites in the film at room temperature allows realisation of higher device efficiencies. We find that conductivity obeys Mott's expression for variable range hopping σ(T) ∝ T-1e-(To/T)1/3. The value of the universal proportionality constant α2 associated with the characteristic temperature has been computed. The effect of electric field on transport has also been studied. The average hopping distance is found to increase with the increase in the electric field at low temperatures, although this dependence is not observed at room temperature. Likewise, the conductivity is also a function of applied field F, and is found to be obey σ(F) ∝ F-1/3e-(Fo/F)1/3 at low temperatures while being field-independent at room temperature.

Laser-synthesized plasmonic HfN-based nanoparticles as a novel multifunctional agent for photothermal therapy

Hafnium nitride nanoparticles (HfN NPs) can offer appealing plasmonic properties at the nanoscale, but the fabrication of stable water-dispersible solutions of non-toxic HfN NPs exhibiting plasmonic features in the window of relative biological transparency presents a great challenge. Here, we demonstrate a solution to this problem by employing ultrashort (femtosecond) laser ablation from a HfN target in organic solutions, followed by a coating of the formed NPs with polyethylene glycol (PEG) and subsequent dispersion in water. We show that the fabricated NPs exhibit plasmonic absorption bands with maxima around 590 nm, 620 nm, and 650 nm, depending on the synthesis environment (ethanol, acetone, and acetonitrile, respectively), which are largely red-shifted compared to what is expected from pure HfN NPs. The observed shift is explained by including nitrogen-deficient hafnium nitride and hafnium oxynitride phases inside the core and oxynitride coating of NPs, as follows from a series of structural characterization studies. We then show that the NPs can provide a strong photothermal effect under 808 nm excitation with a photothermal conversion coefficient of about 62%, which is comparable to the best values reported for plasmonic NPs. MTT and clonogenic assays evidenced very low cytotoxicity of PEG-coated HfN NPs to cancer cells from different tissues up to 100 μg mL-1 concentrations. We finally report a strong photothermal therapeutic effect of HfN NPs, as shown by 100% cell death under 808 nm light irradiation at NP concentrations lower than 25 μg mL-1. Combined with additional X-ray theranostic functionalities (CT scan and photon capture therapy) profiting from the high atomic number (Z = 72) of Hf, plasmonic HfN NPs promise the development of synergetically enhanced modalities for cancer treatment.

Recent advances in spatio-temporally controllable systems for management of glioma

Malignant glioma remains one of the most aggressive intracranial tumors with devastating clinical outcomes despite the great advances in conventional treatment approaches, including surgery and chemotherapy. Spatio-temporally controllable approaches to glioma are now being actively investigated due to the preponderance, including spatio-temporal adjustability, minimally invasive, repetitive properties, etc. External stimuli can be readily controlled by adjusting the site and density of stimuli to exert the cytotoxic on glioma tissue and avoid undesired injury to normal tissues. It is worth noting that the removability of external stimuli allows for on-demand treatment, which effectively reduces the occurrence of side effects. In this review, we highlight recent advancements in drug delivery systems for spatio-temporally controllable treatments of glioma, focusing on the mechanisms and design principles of sensitizers utilized in these controllable therapies. Moreover, the potential challenges regarding spatio-temporally controllable therapy for glioma are also described, aiming to provide insights into future advancements in this field and their potential clinical applications.

Energy-storing DNA-based hydrogel remodels tumor microenvironments for laser-free photodynamic immunotherapy

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.

Pushing Trap-Controlled Persistent Luminescence Materials toward Multi-Responsive Smart Platforms: Recent Advances, Mechanism, and Frontier Applications

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.

Dual-Locked Fluorescent Probes Activated by Aminopeptidase N and the Tumor Redox Environment for High-Precision Imaging of Tumor Boundaries

Clear delineation of tumor margins is essential for accurate resection and decreased recurrence rate in the clinic. Fluorescence imaging is emerging as a promising alternative to traditional visual inspection by surgeons for intraoperative imaging. However, traditional probes lack accuracy in tumor diagnosis, making it difficult to depict tumor boundaries accurately. Herein, we proposed an offensive and defensive integration (ODI) strategy based on the "attack systems (invasive peptidase) and defense systems (reductive microenvironment)" of multi-dimensional tumor characteristics to design activatable fluorescent probes for imaging tumor boundaries precisely. Screened out from a series of ODI strategy-based probes, ANQ performed better than traditional probes based on tumor unilateral correlation by distinguishing between tumor cells and normal cells and minimizing false-positive signals from living metabolic organs. To further improve the signal-to-background ratio in vivo, derivatized FANQ, was prepared and successfully applied to distinguish orthotopic hepatocellular carcinoma tissues from adjacent tissues in mice models and clinical samples. This work highlights an innovative strategy to develop activatable probes for rapid diagnosis of tumors and high-precision imaging of tumor boundaries, providing more efficient tools for future clinical applications in intraoperative assisted resection.

Selenium-Doped Nanoheterojunctions for Highly Efficient Cancer Radiosensitization

Exploring efficient and low-toxicity radiosensitizers to break through the bottleneck of radiation tolerance, immunosuppression and poor prognosis remains one of the critical developmental challenges in radiotherapy. Nanoheterojunctions, due to their unique physicochemical properties, have demonstrated excellent radiosensitization effects in radiation energy deposition and in lifting tumor radiotherapy inhibition. Herein, they doped selenium (Se) into prussian blue (PB) to construct a nano-heterojunction (Se@PB), which could promote the increase of Fe2+/Fe3+ ratio and conversion of Se to a high valence state with Se introduction. The Fe2+-Se-Fe3+ electron transfer chain accelerates the rate of electron transfer on the surface of the nanoparticles, which in turn endows it with efficient X-ray energy transfer and electron transport capability, and enhances radiotherapy physical sensitivity. Furthermore, Se@PB induces glutathione (GSH) depletion and Fe2+ accumulation through pro-Fenton reaction, thereby disturbs the redox balance in tumor cells and enhances biochemical sensitivity of radiotherapy. As an excellent radiosensitizer, Se@PB effectively enhances X-ray induced mitochondrial dysfunction and DNA damage, thereby promotes cell apoptosis and synergistic cervical cancer radiotherapy. This study elucidates the radiosensitization mechanism of Se-doped nanoheterojunction from the perspective of the electron transfer chain and biochemistry reaction, which provides an efficient and low-toxic strategy in radiotherapy.

Size-Dependent Blue Emission from Europium-Doped Strontium Fluoride Nanoscintillators for X-Ray-Activated Photodynamic Therapy

Successful implementation of X-ray-activated photodynamic therapy (X-PDT) is challenging because most photosensitizers (PSs) absorb light in the blue region, but few nanoscintillators produce efficient blue scintillation. Here, efficient blue-emitting SrF2:Eu scintillating nanoparticles (ScNPs) are developed. The optimized synthesis conditions result in cubic nanoparticles with ≈32 nm diameter and blue emission at 416 nm. Coating them with the meso-tetra(n-methyl-4-pyridyl) porphyrin (TMPyP) in a core-shell structure (SrF@TMPyP) results in maximum singlet oxygen (1O2) generation upon X-ray irradiation for nanoparticles with 6TMPyP depositions (SrF@6TMPyP). The 1O2 generation is directly proportional to the dose, does not vary in the low-energy X-ray range (48-160 kVp), but is 21% higher when irradiated with low-energy X-rays than irradiations with higher energy gamma rays. In the clonogenic assay, cancer cells treated with SrF@6TMPyP and exposed to X-rays present a significantly reduced survival fraction compared to the controls. The SrF2:Eu ScNPs and their conjugates stand out as tunable nanoplatforms for X-PDT due to the efficient blue emission from the SrF2:Eu cores; the ability to adjust the scintillation emission in terms of color and intensity by controlling the nanoparticle size; the efficient 1O2 production when conjugated to a PS and the efficacy of killing cancer cells.

Rare Earth Nanoprobes for Targeted Delineation of Triple Negative Breast Cancer and Enhancement of Radioimmunotherapy

Radiotherapy demonstrates a synergistic effect with immunotherapy by inducing a transformation of "immune cold" tumors into "immune hot" tumors in triple negative breast cancer (TNBC). Nevertheless, the effectiveness of immunotherapy is constrained by low expression of tumor-exposed antigens, inadequate inflammation, and insufficient tumor infiltrating lymphocyte (TILs). To address this predicament, novel lutecium-based rare earth nanoparticles (RENPs) are synthesized with the aim of amplifying radiation effect and tumor immune response. The nanoprobe is characterized by neodymium-based down-conversion fluorescence, demonstrating robust photostability, biocompatibility, and targetability. The conjugation of RENPs with a CXCR4 targeted drug enables precise delineation of breast tumors using a near-infrared imaging system and improves radiation efficacy via lutetium-based radio-sensitizer in vivo. Furthermore, the study shows a notable enhancement of immune response through the induction of immunogenic cell death and recruitment of TILs, resulting in the inhibition of tumor progression both in vitro and in vivo models following the administration of nanoparticles. Hence, the novel multifunctional nanoprobes incorporating various lanthanide elements offer the potential for imaging-guided tumor delineation, radio-sensitization, and immune activation post-radiation, thus presenting an efficient radio-immunotherapeutic approach for TNBC.

Radiotherapy activates picolinium prodrugs in tumours

Radiotherapy-induced prodrug activation provides an ideal solution to reduce the systemic toxicity of chemotherapy in cancer therapy, but the scope of the radiation-activated protecting groups is limited. Here we present that the well-established photoinduced electron transfer chemistry may pave the way for developing versatile radiation-removable protecting groups. Using a functional reporter assay, N-alkyl-4-picolinium (NAP) was identified as a caging group that efficiently responds to radiation by releasing a client molecule. When evaluated in a competition experiment, the NAP moiety is more efficient than other radiation-removable protecting groups discovered so far. Leveraging this property, we developed a NAP-derived carbamate linker that releases fluorophores and toxins on radiation, which we incorporated into antibody-drug conjugates (ADCs). These designed ADCs were active in living cells and tumour-bearing mice, highlighting the potential to use such a radiation-removable protecting group for the development of next-generation ADCs with improved stability and therapeutic effects.

Bioimaging and prospects of night pearls-based persistence phosphors in cancer diagnostics

Inorganic persistent phosphors feature great potential for cancer diagnosis due to the long luminescence lifetime, low background scattering, and minimal autofluorescence. With the prominent advantages of near-infrared light, such as deep penetration, high resolution, low autofluorescence, and tissue absorption, persistent phosphors can be used for deep bioimaging. We focus on highlighting inorganic persistent phosphors, emphasizing the synthesis methods and applications in cancer diagnostics. Typical synthetic methods such as the high-temperature solid state, thermal decomposition, hydrothermal/solvothermal, and template methods are proposed to obtain small-size phosphors for biological organisms. The luminescence mechanisms of inorganic persistent phosphors with different excitation are discussed and effective matrixes including galliumate, germanium, aluminate, and fluoride are explored. Finally, the current directions where inorganic persistent phosphors can continue to be optimized and how to further overcome the challenges in cancer diagnosis are summarized.

X-ray activated near-infrared persistent luminescence nanoparticles for trimodality in vivo imaging

As promising luminescence nanoparticles, near-infrared (NIR) persistent luminescence nanoparticles (PLNPs) have received extensive attention in the field of high-sensitivity bioimaging in recent years. However, NIR PLNPs face problems such as short excitation wavelengths and single imaging modes, which limit their applications in in vivo reactivated imaging and multimodal imaging. Here, we report for the first time novel Gd2GaTaO7:Cr3+,Yb3+ (GGTO) NIR PLNPs that integrate X-ray activated NIR persistent luminescence (PersL), high X-ray attenuation and excellent magnetic properties into a single nanoparticle (NP). In this case, Cr3+ is used as the luminescence center. The co-doped Yb3+ and coating effectively enhance the X-ray activated NIR PersL. At the same time, the presence of the high-Z element Ta also makes the GGTO NPs exhibit high X-ray attenuation performance, which can be used as a CT contrast agent to achieve in vivo CT imaging. In addition, since the matrix contains a large amount of Gd, the GGTO NPs show remarkable magnetic properties, which can realize in vivo MR imaging. GGTO NPs combine the trimodal benefits of X-ray reactivated PersL, CT and MR imaging and are suitable for single or combined applications that require high sensitivity and spatial resolution imaging.

Polymorphism-Dependent Organic Room Temperature Phosphorescent Scintillation for X-Ray Imaging

Organic phosphorescent scintillating materials have shown great potential for applications in radiography and radiation detection due to their efficient utilization of excitons. However, revealing the relationship between molecule stacking and the phosphorescent radioluminescence of scintillators is still challenging. This study reports on two phenothiazine derivatives with polymorphism-dependent phosphorescence radioluminescence. The experiments reveal that molecule stacking significantly affects the non-radiation decay of the triplet excitons of scintillators, which further determines the phosphorescence scintillation performance under X-ray irradiation. These phosphorescent scintillators exhibit high radio stability and have a low detection limit of 278 nGys-1. Additionally, the potential application of these scintillators in X-ray radiography, based on their X-ray excited radioluminescence properties, is demonstrated. These findings provide a guideline for obtaining high-performance phosphorescent scintillating materials by shedding light on the effect of crystal packing on the radioluminescence of organic molecules.

X-ray-activated polymerization expanding the frontiers of deep-tissue hydrogel formation

Photo-crosslinking polymerization stands as a fundamental pillar in the domains of chemistry, biology, and medicine. Yet, prevailing strategies heavily rely on ultraviolet/visible (UV/Vis) light to elicit in situ crosslinking. The inherent perils associated with UV radiation, namely the potential for DNA damage, coupled with the limited depth of tissue penetration exhibited by UV/Vis light, severely restrict the scope of photo-crosslinking within living organisms. Although near-infrared light has been explored as an external excitation source, enabling partial mitigation of these constraints, its penetration depth remains insufficient, particularly within bone tissues. In this study, we introduce an approach employing X-ray activation for deep-tissue hydrogel formation, surpassing all previous boundaries. Our approach harnesses a low-dose X-ray-activated persistent luminescent phosphor, triggering on demand in situ photo-crosslinking reactions and enabling the formation of hydrogels in male rats. A breakthrough of our method lies in its capability to penetrate deep even within thick bovine bone, demonstrating unmatched potential for bone penetration. By extending the reach of hydrogel formation within such formidable depths, our study represents an advancement in the field. This application of X-ray-activated polymerization enables precise and safe deep-tissue photo-crosslinking hydrogel formation, with profound implications for a multitude of disciplines.

Nanomaterials-Induced Redox Imbalance: Challenged and Opportunities for Nanomaterials in Cancer Therapy

Cancer cells typically display redox imbalance compared with normal cells due to increased metabolic rate, accumulated mitochondrial dysfunction, elevated cell signaling, and accelerated peroxisomal activities. This redox imbalance may regulate gene expression, alter protein stability, and modulate existing cellular programs, resulting in inefficient treatment modalities. Therapeutic strategies targeting intra- or extracellular redox states of cancer cells at varying state of progression may trigger programmed cell death if exceeded a certain threshold, enabling therapeutic selectivity and overcoming cancer resistance to radiotherapy and chemotherapy. Nanotechnology provides new opportunities for modulating redox state in cancer cells due to their excellent designability and high reactivity. Various nanomaterials are widely researched to enhance highly reactive substances (free radicals) production, disrupt the endogenous antioxidant defense systems, or both. Here, the physiological features of redox imbalance in cancer cells are described and the challenges in modulating redox state in cancer cells are illustrated. Then, nanomaterials that regulate redox imbalance are classified and elaborated upon based on their ability to target redox regulations. Finally, the future perspectives in this field are proposed. It is hoped this review provides guidance for the design of nanomaterials-based approaches involving modulating intra- or extracellular redox states for cancer therapy, especially for cancers resistant to radiotherapy or chemotherapy, etc.

Radiation responsive PROTAC nanoparticles for tumor-specific proteolysis enhanced radiotherapy

Proteolysis targeting chimeras (PROTACs) is a promising strategy for cancer therapy. However, the always-on bioactivity of PROTACs may lead to non-target toxicity, which restricts their antitumor performance. Here, we developed an X-ray radiation responsive PROTAC nanomicelle (RCNprotac) by covalently conjugating a reported small molecule PROTAC (MZ1) to hydrophilic PEG via a diselenide bond-containing carbon chain, which then self-assembled into a 141.80 ± 5.66 nm nanomicelle. The RCNprotac displayed no bioactivity during circulation due to the occupation of the hydroxyl group on the E3 ubiquitin ligand component and could effectively accumulate at the tumor site owing to the enhanced permeability and retention effect. Upon exposure to X-ray radiation, the radiation-sensitive diselenide bonds were broken to specifically release MZ1 for tumor BRD4 protein degradation. Furthermore, the reduction in the BRD4 protein level could increase the tumor's sensitivity to radiation. RCNprotac showed a synergistic enhancement of antitumor effects both in vitro and in vivo. We believe that this X-ray-responsive PROTAC nanomicelle could provide a new strategy for the X-ray-activated spatiotemporally controlled protein degradation and for the BRD4 proteolysis enhanced tumor radiosensitivity.