Chiral Iron Oxide Supraparticles Enable Enantiomer-Dependent Tumor-Targeted Magnetic Resonance Imaging

High-entropy oxide nanozyme for T1/T2 dual-mode magnetic resonance imaging guided photothermal-nanocatalytic tumor therapy

High-entropy oxides (HEOs) have attracted significant attention owing to their broad compositional tunability and high catalytic activity. However, research in this area is still in its early stages, and it is necessary to develop uniform multifunctional high-entropy nanozymes with appropriate sizes and excellent catalytic properties. In this study, we synthesized spherical high-entropy oxide composite carbon (HEO/C) nanoparticles (NPs) with a uniform distribution of particle size. The HEO/C NPs showed efficient peroxidase and catalase activities and photothermal conversion properties in the near-infrared (NIR) biological window. Compared to conventional Fe3O4/C NPs, HEO/C NPs exhibited superior NIR-enhanced enzyme-like activities in catalytic applications. Notably, we report, for the first time, that these HEO/C NPs exhibit T1/T2 dual-mode magnetic resonance imaging (MRI) capabilities, outperforming the single-mode T2 MRI performance of Fe3O4/C NPs. The combination of enzyme-like catalytic and photothermal properties, along with advanced MRI functionality, underscores the significant potential of HEO/C nanozymes for MRI-guided multimodal tumor therapy. This study opens new avenues for the application of high-entropy nanozymes in biomedicine.

Diagnosis of Metastatic Breast Tumor with an Iron-Based Hydrogen-Bonded Organic Framework via T2-Weighted Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) often employs contrast agents (CAs) to improve the visualization of lesions. Although iron-based oxides have been clinically approved as T2 CAs, various obstacles have hindered their widespread commercial use. Consequently, there is a pressing demand for innovative T2-type CAs. Herein, we synthesized an iron-based hydrogen-bonded organic framework (Fe-HOF) from Fe-TCPP and explored its potential as a T2-weighted MRI CA. The Fe-HOF demonstrated a superior relaxivity (r2) of 32.067 mM-1 s-1 and a higher r2/r1 ratio of 45.25 compared to Fe-TCPP. This enhancement may be attributed to the combination of the single-atom form of Fe3+ with its increased radius. Our findings indicate that a 6 μmol [Fe]/kg dose of Fe-HOF significantly improves lesion contrast in T2-weighted MRI scans of subcutaneous tumor model mice and liver metastasis model mice of breast tumor. The simplicity of Fe-HOF' s structure ensures the absence of complex metal ions or ligands during synthesis, and the iron component can be metabolized into the endogenous iron pool, resulting in remarkable biocompatibility and biosafety. These findings pave the way for the design of novel T2-weighted MRI probes tailored for cancer characterization at various stages.

MRI-responsive nanoprobes for visualizing hydrogen peroxide in diabetic liver injury

Diabetic liver injury has emerged as a significant complication associated with diabetes, warranting increased attention. The generation of hydrogen peroxide (H2O2) due to oxidative stress plays a critical role in the onset and progression of this condition. Despite this, there is a scarcity of probes capable of non-invasively, accurately, and reliably visualizing H2O2 levels in deep-seated liver in diabetes-induced liver injury. In this study, we introduce a novel H2O2-responsive magnetic probe (H2O2-RMP), designed for the sensitive imaging of H2O2 in the liver injury caused by diabetes. H2O2-RMP is synthesized through the co-precipitation of a H2O2-responsive amphiphilic polymer, manganese(III) porphyrin (Mn-porphyrin), and iron oxide nanoparticles. When exposed to H2O2, the released iron oxide nanoparticles aggregate, resulting in an increased T2-weighted MR signal intensity. H2O2-RMP not only demonstrates a wide dynamic response range (initial r2 = 9.87 mM-1s-1, Δr2 = 7.69 mM-1s-1), but also exhibits superior selectivity for H2O2 compared to other reactive oxygen species. Importantly, H2O2-RMP exhibits high sensitivity, with a detection limit for hydrogen peroxide as low as 0.56 μM. Moreover, H2O2-RMP has been effectively applied for real-time imaging of H2O2 levels in the livers of diabetic model mice with varying degrees of severity, highlighting its potential for visual diagnosis and monitoring the progression of diabetic liver injury.

Anisotropy-dependent chirality transfer from cellulose nanocrystals to β-FeOOH nanowhiskers

Chiral iron oxides and hydroxides have garnered considerable interest owing to the unique combination of chirality and magnetism. However, improving their g-factor, which is critical for optimizing the chiral magneto-optical response, remains elusive. We demonstrated that the g-factor of β-FeOOH could be boosted by enhancing the anisotropy of nanostructures during a biomimetic mineralization process. Cellulose nanocrystals were used as both mineralization templates and chiral ligands, driving oriented attachment of β-FeOOH nanoparticles and inducing the formation of highly aligned chiral nanowhiskers. Circular dichroism spectra and time-dependent density-functional theory proved that chirality transfer was induced from cellulose nanocrystals to β-FeOOH through ligand-metal charge transfer. Interestingly, chirality transfer was significantly enhanced during the elongation of nanowhiskers. A nearly 34-fold increase in the g-factor was observed when the aspect ratio of nanowhiskers increased from 2.6 to 4.4, reaching a g-factor of 5.7 × 10-3, superior to existing dispersions of chiral iron oxides and hydroxides. Semi-empirical quantum calculations revealed that such a remarkable improvement in the g-factor could be attributed to enhanced dipolar interactions. Cellulose nanocrystals exert vicinal actions on highly anisotropic β-FeOOH with a large dipole moment, increasing structural distortions in the coordination geometry. This mechanism aligns with the static coupling principle of one-electron theory, highlighting the strong interaction potential of supramolecular templates. Furthermore, paramagnetic β-FeOOH nanowhiskers alter the magnetic anisotropy of cellulose nanocrystals, leading to a reversed response of helical photonic films to magnetic fields, promising for real-time optical modulation.

Universal Chiral Nanopaint for Metal Oxide Biomaterials

Chirality is widespread in nature and governs the properties of various materials including inorganic nanomaterials. However, previously reported chiral inorganic materials have been limited to a handful of compositions owing to the physicochemical restrictions that impart chirality. Herein, chiral nanopaint applicable to diverse inorganic materials is presented. Various metal oxide nanoparticles (NPs) show chiroptical properties after coating with our chiral nanopaint, while maintaining their properties, such as magnetic properties. The combination of magnetism and chirality brings biomedical functionalities to chiral NPs, such as anticancer hyperthermia treatment. In vitro, d-nanopainted iron oxide NPs showed more than 50% higher cellular uptake compared to l-nanopainted iron oxide NPs, and this was due to the enantiospecific interaction between the cellular receptors on the cell surface and the chiral NPs. In vivo, d-nanopainted iron oxide NPs showed 4-fold superior anticancer efficiency by magnetic hyperthermia compared to l-nanopainted iron oxide NPs owing to improved adsorption to tumors. These chiral nanoparticles may provide potential synthesis strategies for chiral inorganic biomaterials, which exhibit elaborate combinations of intrinsic physical properties and extrinsic enantioselective properties for a variety of applications.

Chiral Inorganic Nanomaterial-Based Diagnosis and Treatments for Neurodegenerative Diseases

Chiral nanomaterials are widely investigated over recent decades due to their biocompatibility and unique chiral effects. These key properties have significantly promoted the rapid development of chiral nanomaterials in bioengineering and medicine. In this review, the basic principles of constructing chiral nanomaterials along with the latest progress in research are comprehensively summarized. Then, the application of chiral nanomaterials for the diagnosis of neurodegenerative diseases (NDDs) is systematically described. In addition, the significant potential and broad prospects of chiral nanomaterials in the treatment of NDDs are highlighted from several aspects, including the disaggregation of neurofibrils, the scavenging of reactive oxygen species, regulation of the microbial-gut-brain axis, the elimination of senescent cells, and the promotion of directed differentiation in neural stem cells. Finally, a perspective of the challenges and future development of chiral nanomaterials for the treatment of NDDs is provided.

Emerging devices based on chiral nanomaterials

As advanced materials, chiral nanomaterials have recently gained vast attention due to their special geometry-based physical and chemical properties. The fast development of the related science and technology means that various devices involving polarization-based information encryption, photoelectronic and spintronic devices, 3D displays, biomedical sensors and measurement, photonic engineering, electronic engineering, solar devices, etc., been explored extensively. These fields are at their beginning, and much effort needs to be made, including improving the optical, electronic, and magnetic properties of advanced chiral nanomaterials, precisely designing materials, and developing more efficient construction methods. This review tries to offer a whole picture of these state-of-the-art conditions in these fields and offers perspectives on future development.

Core-Shell Fe3O4@C Nanoparticles as Highly Effective T2 Magnetic Resonance Imaging Contrast Agents: In Vitro and In Vivo Studies

Magnetite nanoparticles (Fe3O4 NPs) have been intensively investigated because of their potential biomedical applications due to their high saturation magnetization. In this study, core-shell Fe3O4@C NPs (core = Fe3O4 NPs and shell = amorphous carbons, davg = 35.1 nm) were synthesized in an aqueous solution. Carbon coating terminated with hydrophilic -OH and -COOH groups imparted excellent biocompatibility and hydrophilicity to the NPs, making them suitable for biomedical applications. The Fe3O4@C NPs exhibited ideal relaxometric properties for T2 magnetic resonance imaging (MRI) contrast agents (i.e., high transverse and negligible longitudinal water proton spin relaxivities), making them exclusively induce only T2 relaxation. Their T2 MRI performance as contrast agents was confirmed in vivo by measuring T2 MR images in mice before and after intravenous injection.