Dynamic-Reversible MRI Nanoprobe for Continuous Imaging Redox Homeostasis in Hepatic Ischemia-Reperfusion Injury

A "Dual-Key-and-Lock" MRI Contrast Agent with T1-T2 Switchable Function for Accurate Diagnosis of Tumors

Extremely small iron oxide nanoparticle (ESIONP)-based stimuli-responsive switchable MRI contrast agents (CAs) show great promise for accurate detection of tumors due to their outstanding advantages of high specificity and low background signal. However, currently developed ESIONP-based switchable CAs often suffer single-biomarker-induced responses, which lack absolute specificity to pathological tissues, potentially diminishing diagnostic accuracy. In this study, weak acidity and hypoxia, two of the most remarkable characteristics of tumors, are introduced as dual biomarker stimuli to construct an ESIONP-based switchable MRI CA (DKL-CA), with its signal switch controlled by a "dual-key-and-lock" strategy. Only when DKL-CA is exposed to a coexisting weakly acidic and hypoxic environment can monodispersed ESIONPs form nanoclusters, thereby realizing a switch from the T1 to T2 contrast. Moreover, DKL-CA exhibits favorable biosafety and the capacity for precise tumor diagnosis in tumor-bearing mice. Overall, DKL-CA paves the way for designing highly accurate ESIONP-based MRI CAs for tumor diagnosis.

Three-Dimensional Label-Free Observing of the Self-Assembled Nanoparticles inside a Single Cell at Nanoscale Resolution

Understanding the intracellular behavior of nanoparticles (NPs) plays a key role in optimizing the self-assembly performance of nanomedicine. However, conducting the 3D, label-free, quantitative observation of self-assembled NPs within intact single cells remains a substantial challenge in complicated intracellular environments. Here, we propose a deep learning combined synchrotron radiation hard X-ray nanotomography approach to visualize the self-assembled ultrasmall iron oxide (USIO) NPs in a single cell. The method allows us to explore comprehensive information on NPs, such as their distribution, morphology, location, and interaction with cell organelles, and provides quantitative analysis of the heterogeneous size and morphologies of USIO NPs under diverse conditions. This label-free, in situ method provides a tool for precise characterization of intracellular self-assembled NPs to improve the evaluation and design of a bioresponsive nanomedicine.

A Minimalist Iron Oxide Nanoprobe for the High-Resolution Depiction of Stroke by Susceptibility-Weighted Imaging

The precise mapping of collateral circulation and ischemic penumbra is crucial for diagnosing and treating acute ischemic stroke (AIS). Unfortunately, there exists a significant shortage of high-sensitivity and high-resolution in vivo imaging techniques to fulfill this requirement. Herein, a contrast enhanced susceptibility-weighted imaging (CE-SWI) using the minimalist dextran-modified Fe3O4 nanoparticles (Fe3O4@Dextran NPs) are introduced for the highly sensitive and high-resolution AIS depiction under 9.4 T for the first time. The Fe3O4@Dextran NPs are synthesized via a simple one-pot coprecipitation method using commercial reagents under room temperature. It shows merits of small size (hydrodynamic size 25.8 nm), good solubility, high transverse relaxivity (r2) of 51.3 mM-1s-1 at 9.4 T, and superior biocompatibility. The Fe3O4@Dextran NPs-enhanced SWI can highlight the cerebral vessels readily with significantly improved contrast and ultrahigh resolution of 0.1 mm under 9.4 T MR scanner, enabling the clear spatial identification of collateral circulation in the middle cerebral artery occlusion (MCAO) rat model. Furthermore, Fe3O4@Dextran NPs-enhanced SWI facilitates the precise depiction of ischemia core, collaterals, and ischemic penumbra post AIS through matching analysis with other multimodal MR sequences. The proposed Fe3O4@Dextran NPs-enhanced SWI offers a high-sensitivity and high-resolution imaging tool for individualized characterization and personally precise theranostics of stroke patients.

Current role of magnetic resonance imaging on assessing and monitoring the efficacy of phototherapy

Phototherapy, also known as photobiological therapy, is a non-invasive and highly effective physical treatment method. Its broad use in clinics has led to significant therapeutic results. Phototherapy parameters, such as intensity, wavelength, and duration, can be adjusted to create specific therapeutic effects for various medical conditions. Meanwhile, Magnetic Resonance Imaging (MRI), with its diverse imaging sequences and excellent soft-tissue contrast, provides a valuable tool to understand the therapeutic effects and mechanisms of phototherapy. This review explores the clinical applications of commonly used phototherapy techniques, gives a brief overview of how phototherapy impacts different diseases, and examines MRI's role in various phototherapeutic scenarios. We argue that MRI is crucial for precise targeting, treatment monitoring, and prognosis assessment in phototherapy. Future research and applications will focus on personalized diagnosis and monitoring of phototherapy, expanding its applications in treatment and exploring multimodal imaging technology to enhance diagnostic and therapeutic precision and effectiveness.

Magneto-optical nanosystems for tumor multimodal imaging and therapy in-vivo

Multimodal imaging, which combines the strengths of two or more imaging modalities to provide complementary anatomical and molecular information, has emerged as a robust technology for enhancing diagnostic sensitivity and accuracy, as well as improving treatment monitoring. Moreover, the application of multimodal imaging in guiding precision tumor treatment can prevent under- or over-treatment, thereby maximizing the benefits for tumor patients. In recent years, several intriguing magneto-optical nanosystems with both magnetic and optical properties have been developed, leading to significant breakthroughs in the field of multimodal imaging and image-guided tumor therapy. These advancements pave the way for precise tumor medicine. This review summarizes various types of magneto-optical nanosystems developed recently and describes their applications as probes for multimodal imaging and agents for image-guided therapeutic interventions. Finally, future research and development prospects of magneto-optical nanosystems are discussed along with an outlook on their further applications in the biomedical field.

Monitoring ROS Responsive Fe3O4-based Nanoparticle Mediated Ferroptosis and Immunotherapy via 129Xe MRI

The immune checkpoint blockade strategy has improved the survival rate of late-stage lung cancer patients. However, the low immune response rate limits the immunotherapy efficiency. Here, we report a ROS-responsive Fe3O4-based nanoparticle that undergoes charge reversal and disassembly in the tumor microenvironment, enhancing the uptake of Fe3O4 by tumor cells and triggering a more severe ferroptosis. In the tumor microenvironment, the nanoparticle rapidly disassembles and releases the loaded GOx and the immune-activating peptide Tuftsin under overexpressed H2O2. GOx can consume the glucose of tumor cells and generate more H2O2, promoting the disassembly of the nanoparticle and drug release, thereby enhancing the therapeutic effect of ferroptosis. Combined with Tuftsin, it can more effectively reverse the immune-suppressive microenvironment and promote the recruitment of effector T cells in tumor tissues. Ultimately, in combination with α-PD-L1, there is significant inhibition of the growth of lung metastases. Additionally, the hyperpolarized 129Xe method has been used to evaluate the Fe3O4 nanoparticle-mediated immunotherapy, where the ventilation defects in lung metastases have been significantly improved with complete lung structure and function recovered. The ferroptosis-enhanced immunotherapy combined with non-radiation evaluation methodology paves a new way for designing novel theranostic agents for cancer therapy.

Improving Magnetic Resonance Imaging and Chemodynamic Therapy Properties via Tuning the Fe(II)/Fe(III) Ratio in Hydrophilic Single-Atom Nanobowls

We developed an intrinsic hydrophilic single-atom iron nanobowl (Fe-SANB) for magnetic resonance imaging (MRI)-guided tumor microenvironment-triggered cancer therapy. Benefiting from the sufficient exposure of Fe single atoms and the intrinsic hydrophilicity of the bowl-shaped structure, the Fe-SANBs exhibited a superior performance for T1-weighted MRI with an r1 value of 11.48 mM-1 s-1, which is 3-fold higher than that of the commercial Gd-DTPA (r1 = 3.72 mM-1 s-1). After further coembedding Gd single atoms in the nanobowls, the r1 value can be greatly improved to 19.54 mM-1 s-1. In tumor microenvironment (TME), the Fe-SANBs can trigger pH-induced Fenton-like activity to generate highly toxic hydroxyl radicals for high-efficiency chemodynamic therapy (CDT). Both the MRI and CDT efficiency of these nanobowls can be optimized by tuning the ratio of Fe(II)/Fe(III) in the Fe-SANBs via controlling the calcination temperature. Furthermore, the generation of •OH at the tumor site can be accelerated via the photothermal effect of Fe-SANBs, thus promoting CDT efficacy. Both in vitro and in vivo results confirmed that our nanoplatform exhibited high T1-weighted MRI contrast, robust biocompatibility, and satisfactory tumor treatment, providing a potential nanoplatform for MRI-guided TME-triggered precise cancer therapy.

Walking Dead Macrophage-Based Positive Enhancement MRI for Ultrahighly Efficient Diagnosis of Nephritis

Nephritis is an inflammatory condition of the glomerulus, and the clinical gold standard for its diagnosis is a kidney biopsy. However, obtaining biopsy results can take several days, which does not meet the requirement of rapid diagnosis, especially for rapidly progressive types. To achieve an effective and noninvasive diagnosis, we propose a nephritis-specific, positive magnetic resonance imaging (MRI) contrast agent based on Gd3+ anchored walking dead macrophage Gd-RAW. Gd-RAW exhibits high selectivity for inflammatory renal parenchyma and provides comparable results to histopathology methods. The Gd-RAW-based MRI contrast agent reduces the diagnostic time of nephritis from 14 days of biopsy to 1 h. Furthermore, in a unilateral nephritis model constructed by increasing the glycerol concentration, the T1WI of renal parenchyma exhibits an increased signal-to-noise ratio, which is crucial for evaluating nephritic severity. This work promotes rapid diagnosis of nephritis and potentially provides sufficient evidence for clinicians to offer timely treatment to patients. The methodology of paramagnetic ion-anchored macrophage corpse also opens up new prospects for designing more specific and biosafe MRI contrast agents.

Photonic control of image-guided ferroptosis cancer nanomedicine

Photonic nanomaterials, characterized by their remarkable photonic tunability, empower a diverse range of applications, including cutting-edge advances in cancer nanomedicine. Recently, ferroptosis has emerged as a promising alternative strategy for effectively killing cancer cells with minimizing therapeutic resistance. Novel design of photonic nanomaterials that can integrate photoresponsive-ferroptosis inducers, -diagnostic imaging, and -synergistic components provide significant benefits to effectively trigger local ferroptosis. This review provides a comprehensive overview of recent advancements in photonic nanomaterials for image-guided ferroptosis cancer nanomedicine, offering insights into their strengths, constraints, and their potential as a future paradigm in cancer treatment.

Platelets as delivery vehicles for targeted enrichment of NO· to cerebral glioma for magnetic resonance imaging

Using a magnetic resonance imaging (MRI) contrast agent, MRI has made substantial contributions to glioma diagnosis. Metal-free MRI agents, such as the nano free radical nitric oxide (NO·) micelle, can overcome the inherent toxicity of metal-based agents in certain patient populations. However, the low spatial resolution of nano NO· micelle in MRI limits its clinical development. In this study, we pretreated platelets (PLTs) and loaded them with nano NO· micelles to synthesize NO·@PLT, which can overcome the low contrast and poor in vivo stability of nitroxide-based MRI contrast agents. The PLTs can serve as potential drug carriers for targeting and delivering nano NO· micelles to gliomas and thus increase the contrast in T1-weighted imaging (T1WI) of MRI. This drug carrier system uses the unique tumor-targeting ability of PLTs and takes advantage of the high signal presentation of steady nano NO· micelles in T1WI, thereby ultimately achieving signal amplification of glioma in T1WI. With the effect of PLTs-tumor cell adhesion, NO·@PLT has per-nitroxide transverse relativities of approximately 2-fold greater than those of free NO· particles. These features allow a sufficient NO·@PLT concentration to accumulate in murine subcutaneous glioma tumors up from 5 min to 2.5 h (optimum at 1.5 h) after systemic administration. This results in MRI contrast comparable to that of metal-based agents. This study established a promising metal-free MRI contrast agent, NO·@PLT, for glioma diagnosis, because it has superior spatial resolution owing to its high glioma-targeting ability and has significant translational implications in the clinic.