Dual-Mode Avocado-like All-Iron Nanoplatform for Enhanced T1/T2 MRI-Guided Cancer Theranostic Therapy

Acid-Responsive Decomposable Nanomedicine Based on Zeolitic Imidazolate Frameworks for Near-Infrared Fluorescence Imaging/Chemotherapy Combined Tumor Theranostics

Zeolitic imidazolate framework-8 (ZIF-8) nanoparticles (NPs) are gaining traction in tumor theranostics for their effectiveness in encapsulating both imaging agents and therapeutic drugs. While typically, similar hydrophilic molecules are encapsulated in either pure aqueous or organic environments, few studies have explored co-encapsulation of chemotherapeutic drugs and imaging agents with varying hydrophilicity and, consequently, constructed multifunctional ZIF-8 composite NPs for acid-responsive, near-infrared fluorescence imaging/chemotherapy combined tumor theranostics. Here, we present a one-pot method for the synthesis of uniform Cy5.5&DOX@ZIF-8 nanoparticles in mixed solvents, efficiently achieving simultaneous encapsulation of hydrophilic doxorubicin (DOX) and hydrophobic Cyanine-5.5 (Cy5.5). Surface decoration with dextran (Dex) enhanced colloidal stability and biocompatibility. The method significantly facilitated co-loading of Cy5.5 dyes and DOX drugs, endowing the composite NPs with notable fluorescent imaging capabilities and pH-responsive chemotherapy capacities. In vivo near-infrared fluorescence (NIRF) imaging in A549 tumor-bearing mice demonstrated significant accumulation of Cy5.5 at tumor sites due to enhanced permeability and retention (EPR) effects, with fluorescence intensities approximately 48-fold higher than free Cy5.5. Enhanced therapeutic efficiency was observed in composite NPs compared to free DOX, validating tumor-targeted capability. These findings suggest ZIF-8-based nanomedicines as promising platforms for multifunctional tumor theranostics.

Homologous polydopamine ameliorates haemolysis of melittin for enhancing its anticancer efficacy

Despite exhibiting potent anticancer activity, the strong hemolytic properties of melittin (MEL) significantly restrict its delivery efficiency and clinical applications. To address this issue, we have devised a strategy wherein homologous dopamine (DA), an essential component of bee venom, is harnessed as a vehicle for the synthesis of MEL-polydopamine (PDA) nanoparticles (MP NPs). The ingenious approach lies in the fact that MEL is a basic polypeptide, and the polymerization of DA is also conducted under alkaline conditions, indicating the distinctive advantages of PDA in MEL encapsulation. Furthermore, MP NPs are modified with folic acid to fabricate tumor-targeted nanomedicine (MPF NPs). MPF NPs can ameliorate the hemolysis of MEL in drug delivery and undergo degradation triggered by high levels of reactive oxygen species (ROS) within solid tumors, thereby facilitating MEL release and subsequent restoration of anticancer activity. After cellular uptake, MPF NPs induce cell apoptosis through the PI3K/Akt-mediated p53 signaling pathway. The tumor growth inhibitory rate of MPF NPs in FA receptor-positive 4T1 and CT26 xenograft mice reached 78.04% and 81.66%, which was significantly higher compared to that in FA receptor-negative HepG2 xenograft mice (45.79%). Homologous vehicles provide a new perspective for nanomedicine design.

Unveiling the future: Advancements in MRI imaging for neurodegenerative disorders

Neurodegenerative disorders represent a significant and growing global health challenge, necessitating continuous advancements in diagnostic tools for accurate and early detection. This work explores the recent progress in Magnetic Resonance Imaging (MRI) techniques and their application in the realm of neurodegenerative disorders. The introductory section provides a comprehensive overview of the study's background, significance, and objectives. Recognizing the current challenges associated with conventional MRI, the manuscript delves into advanced imaging techniques such as high-resolution structural imaging (HR-MRI), functional MRI (fMRI), diffusion tensor imaging (DTI), and positron emission tomography-MRI (PET-MRI) fusion. Each technique is critically examined regarding its potential to address theranostic limitations and contribute to a more nuanced understanding of the underlying pathology. A substantial portion of the work is dedicated to exploring the applications of advanced MRI in specific neurodegenerative disorders, including Parkinson's disease, Alzheimer's disease, Huntington's disease, and Amyotrophic Lateral Sclerosis (ALS). In addressing the future landscape, the manuscript examines technological advances, including the integration of machine learning and artificial intelligence in neuroimaging. The conclusion summarizes key findings, outlines implications for future research, and underscores the importance of these advancements in reshaping our understanding and approach to neurodegenerative disorders.

Protease-Mediated T1 Contrast Enhancement of Multilayered Magneto-Gadolinium Nanostructures for Imaging and Magnetic Hyperthermia

In this work, we constructed a multifunctional composite nanostructure for combined magnetic hyperthermia therapy and magnetic resonance imaging based on T1 and T2 signals. First, iron oxide nanocubes with a benchmark heating efficiency for magnetic hyperthermia were assembled within an amphiphilic polymer to form magnetic nanobeads. Next, poly(acrylic acid)-coated inorganic sodium gadolinium fluoride nanoparticles were electrostatically loaded onto the magnetic nanobead surface via a layer-by-layer approach by employing a positively charged enzymatic-cleavable biopolymer. The positive-negative multilayering process was validated through the changes occurring in surface ζ-potential values and structural characterization by transmission electron microscopy (TEM) imaging. These nanostructures exhibit an efficient heating profile, in terms of the specific absorption rates under clinically accepted magnetic field conditions. The addition of protease enzyme mediates the degradation of the surface layers of the nanostructures with the detachment of gadolinium nanoparticles from the magnetic beads and exposure to the aqueous environment. Such a process is associated with changes in the T1 relaxation time and contrast and a parallel decrease in the T2 signal. These structures are also nontoxic when tested on glioblastoma tumor cells up to a maximum gadolinium dose of 125 μg mL-1, which also corresponds to a iron dose of 52 μg mL-1. Nontoxic nanostructures with such enzyme-triggered release mechanisms and T1 signal enhancement are desirable for tracking tumor microenvironment release with remote T1-guidance and magnetic hyperthermia therapy actuation to be done at the diseased site upon verification of magnetic resonance imaging (MRI)-guided release.

Advance Progress in Assembly Mechanisms of Carrier-Free Nanodrugs for Cancer Treatment

Nanocarriers have been widely studied and applied in the field of cancer treatment. However, conventional nanocarriers still suffer from complicated preparation processes, low drug loading, and potential toxicity of carriers themselves. To tackle the hindrance, carrier-free nanodrugs with biological activity have received increasing attention in cancer therapy. Extensive efforts have been made to exploit new self-assembly methods and mechanisms to expand the scope of carrier-free nanodrugs with enhanced therapeutic performance. In this review, we summarize the advanced progress and applications of carrier-free nanodrugs based on different types of assembly mechanisms and strategies, which involved noncovalent interactions, a combination of covalent bonds and noncovalent interactions, and metal ions-coordinated self-assembly. These carrier-free nanodrugs are introduced in detail according to their assembly and antitumor applications. Finally, the prospects and existing challenges of carrier-free nanodrugs in future development and clinical application are discussed. We hope that this comprehensive review will provide new insights into the rational design of more effective carrier-free nanodrug systems and advancing clinical cancer and other diseases (e.g., bacterial infections) infection treatment.

Recent progress in tannic acid based approaches as a natural polyphenolic biomaterial for cancer therapy: A review

Significant advancements have been noticed in cancer therapy for decades. Despite this, there are still many critical challenges ahead, including multidrug resistance, drug instability, and side effects. To overcome obstacles of these problems, various types of materials in biomedical research have been explored. Chief among them, the applications of natural compounds have grown rapidly due to their superb biological activities. Natural compounds, especially polyphenolic compounds, play a positive and great role in cancer therapy. Tannic acid (TA), one of the most famous polyphenols, has attracted widespread attention in the field of cancer treatment with unique structural, physicochemical, pharmaceutical, anticancer, antiviral, antioxidant and other strong biological features. This review concentrated on the basic structure along with the important role of TA in tuning oncological signal pathways firstly, and then focused on the use of TA in chemotherapy and preparation of delivery systems including nanoparticles and hydrogels for cancer therapy. Besides, the application of TA/Fe3+ complex coating in photothermal therapy, chemodynamic therapy, combined therapy and theranostics is discussed.

Hydrogen-Bonded Organic Frameworks Chelated Manganese for Precise Magnetic Resonance Imaging Diagnosis of Cancers

Magnetic resonance imaging (MRI) is an important tool in the diagnosis of many cancers. However, clinical gadolinium (Gd)-based MRI contrast agents have limitations, such as large doses and potential side effects. To address these issues, we developed a hydrogen-bonded organic framework-based MRI contrast agent (PFC-73-Mn). Due to the hydrogen-bonded interaction of water molecules and the restricted rotation of manganese ions, PFC-73-Mn exhibits high longitudinal relaxation r1 (5.03 mM-1 s-1) under a 3.0 T clinical MRI scanner. A smaller intravenous dose (8 μmol of Mn/kg) of PFC-73-Mn can provide strong contrast and accurate diagnosis in multiple kinds of cancers, including breast tumor and ultrasmall orthotopic glioma. PFC-73-Mn represents a prospective new approach in tumor imaging, especially in early-stage cancer.

Polydopamine-containing nano-systems for cancer multi-mode diagnoses and therapies: A review

Polydopamine (PDA) has fascinating properties such as inherent biocompatibility, simple preparation, strong near-infrared absorption, high photothermal conversion efficiency, and strong metal ion chelation, which have catalyzed extensive research in PDA-containing multifunctional nano-systems particularly for biomedical applications. Thus, it is imperative to overview synthetic strategies of various PDA-containing nanoparticles (NPs) for state-of-the-art cancer multi-mode diagnoses and therapies applications, and offer a timely and comprehensive summary. In this review, we will focus on the synthetic approaches of PDA NPs, and summarize the construction strategies of PDA-containing NPs with different structure forms. Additionally, the application of PDA-containing NPs in bioimaging such as photoacoustic imaging, fluorescence imaging, magnetic resonance imaging and other imaging modalities will be reviewed. We will especially offer an overview of their therapeutic applications in tumor chemotherapy, photothermal therapy, photodynamic therapy, photocatalytic therapy, sonodynamic therapy, radionuclide therapy, gene therapy, immunotherapy and combination therapy. At the end, the current trends, limitations and future prospects of PDA-containing nano-systems will be discussed. This review aims to provide guidelines for new scientists in the field of how to design PDA-containing NPs and what has been achieved in this area, while offering comprehensive insights into the potential of PDA-containing nano-systems used in cancer diagnosis and treatment.

Magnetic Nanoparticle-Based High-Performance Positive and Negative Magnetic Resonance Imaging Contrast Agents

In recent decades, magnetic nanoparticles (MNPs) have attracted considerable research interest as versatile substances for various biomedical applications, particularly as contrast agents in magnetic resonance imaging (MRI). Depending on their composition and particle size, most MNPs are either paramagnetic or superparamagnetic. The unique, advanced magnetic properties of MNPs, such as appreciable paramagnetic or strong superparamagnetic moments at room temperature, along with their large surface area, easy surface functionalization, and the ability to offer stronger contrast enhancements in MRI, make them superior to molecular MRI contrast agents. As a result, MNPs are promising candidates for various diagnostic and therapeutic applications. They can function as either positive (T₁) or negative (T₂) MRI contrast agents, producing brighter or darker MR images, respectively. In addition, they can function as dual-modal T₁ and T₂ MRI contrast agents, producing either brighter or darker MR images, depending on the operational mode. It is essential that the MNPs are grafted with hydrophilic and biocompatible ligands to maintain their nontoxicity and colloidal stability in aqueous media. The colloidal stability of MNPs is critical in order to achieve a high-performance MRI function. Most of the MNP-based MRI contrast agents reported in the literature are still in the developmental stage. With continuous progress being made in the detailed scientific research on them, their use in clinical settings may be realized in the future. In this study, we present an overview of the recent developments in the various types of MNP-based MRI contrast agents and their in vivo applications.

Tumor microenvironment responsive T1-T2 dual-mode contrast agent Fe3O4@ZIF-8-Zn-Mn NPs for in vivo magnetic resonance imaging

Activated T₁-T₂ contrast agents can effectively improve the sensitivity and diagnosis accuracy of magnetic resonance imaging (MRI), but the construction of such contrast agents still remains a great challenge. In this work, a pH- and glutathione (GSH)-responsive T₁-T₂ dual-mode contrast agent, Fe₃O₄@ZIF-8-Zn-Mn nanoparticles (NPs), with simple components was constructed via simply assembly of paramagnetic Mn²⁺ ions (as T₁ contrast agent) and Fe₃O₄ NPs (as T₂ contrast agent) into a pH- and GSH-sensitive Zn-zeolitic imidazole framework (ZIF-8) matrix. Under neutral conditions, Fe₃O₄@ZIF-8-Zn-Mn NPs show good stability and weak T₁-T₂ dual-mode MRI contrast effect (r₁ = 0.82 mM^-1 s^-1, r₂ = 21.28 mM^-1 s^-1) due to the magnetic interference between Fe₃O₄ NPs and paramagnetic Mn²⁺ ions. In contrast, under acidic environment (pH = 6.5-5.5) and in the present GSH (0-4 mM), Fe₃O₄@ZIF-8-Zn-Mn NPs can be disassembled and release Fe₃O₄ NPs and paramagnetic Mn²⁺ ions, which causes simultaneous recovery of T₁ and T₂ imaging performances with enhanced r₁ and r₂ relaxation values up to 6.9 and 9.9 times, respectively. Moreover, in vivo MRI experiments showed that after the intravenous injection of Fe₃O₄@ZIF-8-Zn-Mn NPs for about one hour, the T₁-weighted imaging of the tumor site becomes brighter with T₁ signal enhanced by about 31%, while the T₂-weighted imaging of the tumor site becomes darker with T₂ signal enhanced by nearly 30%, suggesting the great potential of Fe₃O₄@ZIF-8-Zn-Mn NPs to be used as a tumor microenvironment-responsive T₁-T₂ dual-mode contrast agent for sensitive tumor imaging.

Shape programmable T1-T2 dual-mode MRI nanoprobes for cancer theranostics

The shape effect is an important parameter in the design of novel nanomaterials. Engineering the shape of nanomaterials is an effective strategy for optimizing their bioactive performance. Nanomaterials with a unique shape are beneficial to blood circulation, tumor targeting, cell uptake, and even improved magnetism properties. Therefore, magnetic resonance imaging (MRI) nanoprobes with different shapes have been extensively focused on in recent years. Different from other multimodal imaging techniques, dual-mode MRI can provide imaging simultaneously by a single instrument, which can avoid differences in penetration depth, and the spatial and temporal resolution of multiple imaging devices, and ensure the accurate matching of spatial and temporal imaging parameters for the precise diagnosis of early tumors. This review summarizes the latest developments of nanomaterials with various shapes for T₁-T₂ dual-mode MRI, and highlights the mechanism of how shape intelligently affects nanomaterials' longitudinal or transverse relaxation, namely sphere, hollow, core-shell, cube, cluster, flower, dumbbell, rod, sheet, and bipyramid shapes. In addition, the combination of T₁-T₂ dual-mode MRI nanoprobes and advanced therapeutic strategies, as well as possible challenges from basic research to clinical transformation, are also systematically discussed. Therefore, this review will help others quickly understand the basic information on dual-mode MRI nanoprobes and gather thought-provoking ideas to advance the subfield of cancer nanomedicine.

Kartogenin (KGN)/synthetic melanin nanoparticles (SMNP) loaded theranostic hydrogel scaffold system for multiparametric magnetic resonance imaging guided cartilage regeneration

Cartilage regeneration after injury is still a great challenge in clinics, which suffers from its avascularity and poor proliferative ability. Herein we designed a novel biocompatible cellulose nanocrystal/GelMA (gelatin-methacrylate anhydride)/HAMA (hyaluronic acid-methacrylate anhydride)-blended hydrogel scaffold system, loaded with synthetic melanin nanoparticles (SMNP) and a bioactive drug kartogenin (KGN) for theranostic purpose. We found that the SMNP-KGN/Gel showed favorable mechanical property, thermal stability, and distinct magnetic resonance imaging (MRI) contrast enhancement. Meanwhile, the sustained release of KGN could recruit bone-derived mesenchymal stem cells to proliferate and differentiate into chondrocytes, which promoted cartilage regeneration in vitro and in vivo. The hydrogel degradation and cartilage restoration were simultaneously monitored by multiparametric MRI for 12 weeks, and further confirmed by histological analysis. Together, these results validated the multifunctional hydrogel as a promising tissue engineering platform for noninvasive imaging-guided precision therapy in cartilage regenerative medicine.

Tumor Microenvironment Stimuli-Responsive Single-NIR-Laser Activated Synergistic Phototherapy for Hypoxic Cancer by Perylene Functionalized Dual-Targeted Upconversion Nanoparticles

Although synergistic therapy has shown great promise for effective treatment of cancer, the unsatisfactory therapeutic efficacy of photothermal therapy/photodynamic therapy is resulted from the absorption wavelength mismatch, tumor hypoxia, photosensitizer leakage, and inability in intelligent on-demand activation. Herein, based on the characteristics of tumor microenvironment (TME), such as the slight acidity, hypoxia, and overexpression of H₂ O₂ , a TME stimuli-responsive and dual-targeted composite nanoplatform (UCTTD-PC4) is strategically explored by coating a tannic acid (TA)/Fe³⁺ nanofilm with good biocompatibility onto the upconversion nanoparticles in an ultrafast, green and simple way. The pH-responsive feature of UCTTD-PC4 remains stable during the blood circulation, while rapidly releases Fe³⁺ in the slightly acidic tumor cells, which results in catalyzing H₂ O₂ to produce O₂ and overcoming the tumor hypoxia. Notably, the emission spectrum of the UCTTD perfectly matches the absorption spectrum of the photosensitizer (perylene probe (PC4)) to achieve the enhanced therapeutic effect triggered by a single laser. This study provides a new strategy for the rational design and development of the safe and efficient single near-infrared laser-triggered synergistic treatment platform for hypoxic cancer under the guidance of multimodal imaging.

Chemical Modulation of Glucose Metabolism with a Fluorinated CaCO3 Nanoregulator Can Potentiate Radiotherapy by Programming Antitumor Immunity

Tumor hypoxia and acidity are well-known features in solid tumors that cause immunosuppression and therapeutic resistance. Herein, we rationally synthesized a multifunctional fluorinated calcium carbonate (fCaCO₃) nanoregulator by coating CaCO₃ nanoparticles with dopamine-grafted perfluorosebacic acid (DA₂-PFSEA) and ferric ions by utilizing their coordination interaction. After PEGylation, the obtained fCaCO₃-PEG showed high loading efficacy to perfluoro-15-crown-5-ether (PFCE), a type of perfluorocarbon with high oxygen solubility, thereby working as both oxygen nanoshuttles and proton sponges to reverse tumor hypoxia and acidity-induced resistance to radiotherapy. The as-prepared PFCE@fCaCO₃-PEG could not only function as long-circulating oxygen nanoshuttles to attenuate tumor hypoxia but also neutralize the acidic tumor microenvironment by restricting the production of lactic acid and reacting with extracellular protons. As a result, treatment with PFCE@fCaCO₃-PEG could improve the therapeutic outcome of radiotherapy toward two murine tumors with distinct immunogenicity. The PFCE@fCaCO₃-PEG-assisted radiotherapy could also collectively inhibit the growth of unirradiated tumors and reject rechallenged tumors by synergistically eliciting protective antitumor immunity. Therefore, our work presents the preparation of fluorinated CaCO₃ nanoregulators to reverse tumor immunosuppression and potentiate radiotherapy through chemically modulating tumor hypoxic and acidic microenvironments tightly associated with tumor glucose metabolism.

Applications of metal-phenolic networks in nanomedicine: a review

The exploration of nanomaterials is beneficial for the development of nanomedicine and human medical treatment. Metal-phenolic networks (MPNs) have been introduced as a nanoplatform for versatile functional hybrid nanomaterials and have attracted extensive attention due to their simple preparation, excellent properties and promising medical application prospects. This review presents an overview of recent synthesis methods for MPNs, their unique biomedical properties and the research progress in their application in disease detection and treatment. First, the synthesis methods of MPNs are summarised, and then the advantages and applicability of each assembly method are emphasised. The various functions exhibited by MPNs in biomedical applications are then introduced. Finally, the latest research progress in MPN-based nanoplatforms in the biomedical field is discussed, and their future research and application are investigated.

NIR/MRI-Guided Oxygen-Independent Carrier-Free Anti-Tumor Nano-Theranostics

Imaging-guided photothermal therapy (PTT)/photodynamic therapy (PDT) for cancer treatment are beneficial for precise localization of the malignant lesions and combination of multiple cell killing mechanisms in eradicating stubborn thermal-resistant cancer cells. However, overcoming the adverse impact of tumor hypoxia on PDT efficacy remains a challenge. Here, carrier-free nano-theranostic agents are developed (AIBME@IR780-APM NPs) for magnetic resonance imaging (MRI)-guided synergistic PTT/thermodynamic therapy (TDT). Two IR780 derivatives are synthesized as the subject of nanomedicine to confer the advantages for the nanomedicine, which are by feat of amphiphilic IR780-PEG to enhance the sterical stability and reduce the risk from reticuloendothelial system uptake, and IR780-ATU to chelate Mn²⁺ for T₁ -weighted MRI. Dimethyl 2,2'-azobis(2-methylpropionate) (AIBME), acting as thermally decomposable radical initiators, are further introduced into nanosystems with the purpose of generating highly cytotoxic alkyl radicals upon PTT launched by IR780 under 808 nm laser irradiation. Therefore, the sequentially generated heat and alkyl radicals synergistically induce cell death via synergistic PTT/TDT, ignoring tumor hypoxia. Moreover, these carrier-free nano-theranostic agents present satisfactory biocompatibility, which could be employed as a powerful weapon to hit hypoxic tumors via MRI-guided oxygen-independent PTT and photonic TDT.

Gd2O3-mesoporous silica/gold nanoshells: A potential dual T1/T2 contrast agent for MRI-guided localized near-IR photothermal therapy

A promising clinical trial utilizing gold-silica core-shell nanostructures coated with polyethylene glycol (PEG) has been reported for near-infrared (NIR) photothermal therapy (PTT) of prostate cancer. The next critical step for PTT is the visualization of therapeutically relevant nanoshell (NS) concentrations at the tumor site. Here we report the synthesis of PEGylated Gd₂O₃-mesoporous silica/gold core/shell NSs (Gd₂O₃-MS NSs) with NIR photothermal properties that also supply sufficient MRI contrast to be visualized at therapeutic doses (≥10⁸ NSs per milliliter). The nanoparticles have r₁ relaxivities more than three times larger than those of conventional T₁ contrast agents, requiring less concentration of Gd³⁺ to observe an equivalent signal enhancement in T₁-weighted MR images. Furthermore, Gd₂O₃-MS NS nanoparticles have r₂ relaxivities comparable to those of existing T₂ contrast agents, observed in agarose phantoms. This highly unusual combination of simultaneous T₁ and T₂ contrast allows for MRI enhancement through different approaches. As a rudimentary example, we demonstrate T₁/T₂ ratio MR images with sixfold contrast signal enhancement relative to its T₁ MRI and induced temperature increases of 20 to 55 °C under clinical illumination conditions. These nanoparticles facilitate MRI-guided PTT while providing real-time temperature feedback through thermal MRI mapping.

Recent advances in engineering iron oxide nanoparticles for effective magnetic resonance imaging

Iron oxide nanoparticle (IONP) with unique magnetic property and high biocompatibility have been widely used as magnetic resonance imaging (MRI) contrast agent (CA) for long time. However, a review which comprehensively summarizes the recent development of IONP as traditional T₂ CA and its new application for different modality of MRI, such as T₁ imaging, simultaneous T₂/T₁ or MRI/other imaging modality, and as environment responsive CA is rare. This review starts with an investigation of direction on the development of high-performance MRI CA in both T₂ and T₁ modal based on quantum mechanical outer sphere and Solomon–Bloembergen–Morgan (SBM) theory. Recent rational attempts to increase the MRI contrast of IONP by adjusting the key parameters, including magnetization, size, effective radius, inhomogeneity of surrounding generated magnetic field, crystal phase, coordination number of water, electronic relaxation time, and surface modification are summarized. Besides the strategies to improve r₂ or r₁ values, strategies to increase the in vivo contrast efficiency of IONP have been reviewed from three different aspects, those are introducing second imaging modality to increase the imaging accuracy, endowing IONP with environment response capacity to elevate the signal difference between lesion and normal tissue, and optimizing the interface structure to improve the accumulation amount of IONP in lesion. This detailed review provides a deep understanding of recent researches on the development of high-performance IONP based MRI CAs. It is hoped to trigger deep thinking for design of next generation MRI CAs for early and accurate diagnosis.

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T₂ contrast capacity of iron oxide nanoparticles (IONPs) could be improved based on quantum mechanical outer sphere theory.

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IONPs could be expand to be used as effective T₁ CAs by improving q value, extending τ_s, and optimizing interface structure.

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Environment responsive MRI CAs have been developed to improve the diagnosis accuracy.

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Introducing other imaging contrast moiety into IONPs could increase the contrast efficiency.

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Optimizing in vivo behavior of IONPs have been proved to enlarge the signal difference between normal tissue and lesion.

Metal Ion-Directed Functional Metal-Phenolic Materials

Metal ions are ubiquitous in nature and play significant roles in assembling functional materials in fields spanning chemistry, biology, and materials science. Metal-phenolic materials are assembled from phenolic components in the presence of metal ions through the formation of metal-organic complexes. Alkali, alkali-earth, transition, and noble metal ions as well as metalloids interacting with phenolic building blocks have been widely exploited to generate diverse hybrid materials. Despite extensive studies on the synthesis of metal-phenolic materials, a comprehensive summary of how metal ions guide the assembly of phenolic compounds is lacking. A fundamental understanding of the roles of metal ions in metal-phenolic materials engineering will facilitate the assembly of materials with specific and functional properties. In this review, we focus on the diversity and function of metal ions in metal-phenolic material engineering and emerging applications. Specifically, we discuss the range of underlying interactions, including (i) cation-π, (ii) coordination, (iii) redox, and (iv) dynamic covalent interactions, and highlight the wide range of material properties resulting from these interactions. Applications (e.g., biological, catalytic, and environmental) and perspectives of metal-phenolic materials are also highlighted.

Tannic acid: a crosslinker leading to versatile functional polymeric networks: a review

With the thriving of mussel-inspired polyphenol chemistry as well as the demand for low-cost analogues to polydopamine in adhesive design, tannic acid has gradually become a research focus because of its wide availability, health benefits and special chemical properties. As a natural building block, tannic acid could be used as a crosslinker either supramolecularly or chemically, ensuring versatile functional polymeric networks for various applications. Up to now, a systematic summary on tannic-acid-based networks has still been waiting for an update and outlook. In this review, the common features of tannic acid are summarized in detail, followed by the introduction of covalent and non-covalent crosslinking methods leading to various tannic-acid-based materials. Moreover, recent progress in the application of tannic acid composites is also summarized, including bone regeneration, skin adhesives, wound dressings, drug loading and photothermal conversion. Above all, we also provide further prospects concerning tannic-acid-crosslinked materials.

Theranostic applications of stimulus-responsive systems based on Fe2O3

According to the interaction of nanoparticles with biological systems, enthusiasm for nanotechnology in biomedical applications has been developed in the past decades. Fe2O3 nanoparticles, as the most stable iron oxide, have special merits that make them useful widely for detecting diseases, therapy, drug delivery, and monitoring the therapeutic process. This review presents the fabrication methods of Fe2O3-based materials and their photocatalytic and magnetic properties. Then, we highlight the application of Fe2O3-based nanoparticles in diagnosis and imaging, different therapy methods, and finally, stimulus-responsive systems, such as pH-responsive, magnetic-responsive, redox-responsive, and enzyme-responsive, with an emphasis on cancer treatment. In addition, the potential of Fe2O3 to combine diagnosis and therapy within a single particle called theranostic agent will be discussed.

Metal-Phenolic-Network-Coated Dendrimer-Drug Conjugates for Tumor MR Imaging and Chemo/Chemodynamic Therapy via Amplification of Endoplasmic Reticulum Stress

Amplification of endoplasmic reticulum stress (ERS) to realize enhanced cancer therapy has been considered to be unique in current cancer nanomedicine design. Herein, the design of metal-phenolic-network-coated dendrimer-drug conjugates as a novel theranostic nanoplatform based on ERS amplification is reported. In the design, acetylated generation-5 poly(amidoamine) dendrimers are conjugated with an ERS drug, toyocamycin (Toy), through the attached phenylboronic acid moiety, and coated with an iron (Fe)-tannic acid (TF) network. The generated nanocomplexes with a size of 50.2 nm are stable under the physiological environment, and can rapidly release Toy under the tumor microenvironment due to the pH- and reactive-oxygen-species-responsive boronic ester bonds to effectively inhibit the ERS-mediated cancer cell adaptation. Meanwhile, the coated TF network enables the nanocomplexes to generate cytotoxic hydroxyl radicals through a Fenton reaction, amplifying the ERS for improved chemo/chemodynamic therapy of cancer cells in vitro and a xenografted breast tumor model in vivo. Moreover, the coating of TF also renders the complexes with an eminent r₁ relaxivity for in vivo T₁ -weighted tumor magnetic resonance imaging. The created intelligent nanocomplexes may represent an advanced nanomedicine formulation uniquely integrated with a metal-phenolic network and dendrimer nanotechnology for imaging-guided cancer therapy through ERS amplification.

Gold Nanorods with Spatial Separation of CeO2 Deposition for Plasmonic-Enhanced Antioxidant Stress and Photothermal Therapy of Alzheimer's Disease

Activities of catalase (CAT) and superoxide dismutase (SOD) of ceria nanoparticles (CeO₂ NPs) provide the possibility for their application in nervous system oxidative stress diseases including Alzheimer's disease (AD). The addition of hot electrons produced by a plasma photothermal effect can expand the photocatalytic activity of CeO₂ to the near-infrared region (NIR), significantly improving its redox performance. Therefore, we coated both ends of gold nanorods (Au NRs) with CeO₂ NPs, and photocatalysis and photothermal therapy in the NIR are introduced into the treatment of AD. Meanwhile, the spatially separate structure enhances the catalytic performance and photothermal conversion efficiency. In addition, the photothermal effect significantly improves the permeability of the blood-brain barrier (BBB) and overcomes the shortcomings of traditional anti-AD drugs. To further improve the therapeutic efficiency, Aβ-targeted inhibitory peptides were modified on the middle surface of gold nanorods to synthesize KLVFF@Au-CeO₂ (K-CAC) nanocomposites. We have verified their biocompatibility and therapeutic effectiveness at multiple levels in vitro and in vivo, which have a profound impact on the research and clinical transformation of nanotechnology in AD therapy.

Skin-permissible NIR-actuated hyperthermia using a photothermally responsive hydrogel membrane for the effective treatment of antibiotic-resistant bacterial infection

With the long-term widespread overuse of antibiotics, a large number of antibiotic-resistant bacteria have emerged and become a serious threat to healthcare systems. As an alternative strategy, near-infrared light (NIR)-actuated photothermal treatment has been developed for killing antibiotic-resistant bacteria. Although promising, the widespread applications of photothermal antibacterial platforms face great challenges due to the skin-harmful high laser irradiation. In this work, a novel NIR-responsive hydrogel membrane for effective photothermal sterilization upon light irradiation at skin-permissible intensity has been successfully prepared using a sodium alginate-based hydrogel membrane containing tannic acid-Fe(III) compounds (STF). The as-prepared STF displayed excellent mechanical capacity and fabricability. More importantly, the as-prepared STF revealed superior photothermal efficiency under a low-intensity NIR irradiation (0.3 W cm^-2), which was below the maximum permissible exposure of skin (0.33 W cm^-2). In addition, the STF showed the excellent performance of photothermal sterilization for MRSA both in vitro and in vivo. Furthermore, the STF showed good biocompatibility. Based on the simple synthesis method, outstanding mechanical properties, excellent photothermal sterilization performance and good biocompatibility, the STF could be a promising wound dressing for antibiotic-resistant bacterial infections.

Tumor-penetrating iron oxide nanoclusters for T1/T2 dual mode MR imaging-guided combination therapy

A hyaluronic acid (HA)-stabilized iron oxide nanocluster (Fe2O3@PFDH NC) was developed as an intelligent tumor-penetrating theranostic nanoagent for dual-mode MRI guided chemo-photothermal therapy.

Rapidly clearable MnCo2O4@PAA as novel nanotheranostic agents for T1/T2 bimodal MRI imaging-guided photothermal therapy

Integrating multi-modal imaging and therapy functions into a nanoplatform has been recognized as a promising strategy for cancer theranostics with high accuracy and efficiency. However, there are still some challenges, such as the complicated synthesis process and instability. Herein, we successfully prepared clearable MnCo₂O₄ nanodots modified with polyacrylic acid (MnCo₂O₄@PAA) as nanoagents for T₁/T₂ bimodal MRI imaging-guided PTT. Owing to their intrinsic magnetic properties, single MnCo₂O₄@PAA nanomaterials can serve as contrasts for T₁/T₂ bimodal MRI, providing precise diagnotic information. Moreover, excellent absorption in the NIR biowindow endows MnCo₂O₄@PAA with good photothermal performance, and the ultrasmall size of MnCo₂O₄@PAA allows them to penetrate deeply into tumors, resulting in a good anticancer effect in vitro and in vivo. What is more, MnCo₂O₄@PAA can almost be completely cleared from mice at 7 d postinjection, implying their negligible long-term toxicity. These findings demonstrate that MnCo₂O₄@PAA are promising nanoagents for cancer diagnosis and treatment, which have great potential for clinical applications.

Dynamic nanoassemblies of nanomaterials for cancer photomedicine

Photomedicine has long been used for treating cancerous diseases. With advances in chemical and material sciences, various types of light-activated photosensitizers (PSs) have been developed for effective photodynamic therapy (PDT) and photothermal therapy (PTT). However, conventional organic/inorganic materials-based PSs lack disease recognition capability and show limited therapeutic effects in addition to side effects. Recently, intelligent dynamic nanoassemblies that are activated in a tumor environment have been extensively researched to target diseased tissues more effectively, for increasing therapeutic effectiveness while minimizing side effects. This paper presents the latest dynamic nanoassemblies for effective PDT or PTT and combination phototherapies, including immunotherapy and image-guided therapy. Dynamic self-assembly exhibits great potential for clinical translation in diagnosis and treatment through its integrated versatility. Nanoassemblies based on multidisciplinary technology are a promising technique for treating incurable cancerous diseases in the future.

Preparation of doxorubicin-loaded porous iron Oxide@ polydopamine nanocomposites for MR imaging and synergistic photothermal-chemotherapy of cancer

Recently, the development of biosafe nanocomposites with integrated diagnosis and therapeutic modality is received great attention in anti-cancer drug delivery. In this sturdy, we developed a multifunctional PION@PDA-PEG nanocomposite that combines the functions of magnetic resonance (MR) imaging, photothermal therapy (PTT) and chemotherapy into one single nanoprobe. The spherical and uniform-sized porous iron oxide nanoparticles (PION) were synthesized via a simple solvothermal method. Subsequently, a near-infrared light (NIR) sensitive polydopamine (PDA) shell was directly coated on the surface of PIONs to form monodisperse and biosafe core-shell nanocomposites, Thereafter, the surface of nanocomposites was further modified with polyethylene glycol (PEG) to prolong their blood circulation lifetime. The prepared PION@PDA-PEG showed excellent biocompatibility and promising MR imaging contrast agent capability. Furthermore, the porous structure of PION and the abundant functional groups of PDA shell permitted the remarkable drug loading capacity of more than 24.1 wt%. In addition, the synergistic photothermal- chemotherapy exhibited obvious enhanced anti-tumor effect in in-vitro cell experiment. These results suggest that the developed PION@PDA-PEG nanocomposite can be utilized as an efficient drug nanocarrier for biomedical applications including MR imaging and photothermal-chemotherapy.

Recent Advances in Multimodal Molecular Imaging of Cancer Mediated by Hybrid Magnetic Nanoparticles

Cancer is the second leading cause of death in the world, which is why it is so important to make an early and very precise diagnosis to obtain a good prognosis. Thanks to the combination of several imaging modalities in the form of the multimodal molecular imaging (MI) strategy, a great advance has been made in early diagnosis, in more targeted and personalized therapy, and in the prediction of the results that will be obtained once the anticancer treatment is applied. In this context, magnetic nanoparticles have been positioned as strong candidates for diagnostic agents as they provide very good imaging performance. Furthermore, thanks to their high versatility, when combined with other molecular agents (for example, fluorescent molecules or radioisotopes), they highlight the advantages of several imaging techniques at the same time. These hybrid nanosystems can be also used as multifunctional and/or theranostic systems as they can provide images of the tumor area while they administer drugs and act as therapeutic agents. Therefore, in this review, we selected and identified more than 160 recent articles and reviews and offer a broad overview of the most important concepts that support the synthesis and application of multifunctional magnetic nanoparticles as molecular agents in advanced cancer detection based on the multimodal molecular imaging approach.

Metal-Coordinated Supramolecular Self-Assemblies for Cancer Theranostics

Metal-coordinated supramolecular nanoassemblies have recently attracted extensive attention as materials for cancer theranostics. Owing to their unique physicochemical properties, metal-coordinated supramolecular self-assemblies can bridge the boundary between traditional inorganic and organic materials. By tailoring the structural components of the metal ions and binding ligands, numerous multifunctional theranostic nanomedicines can be constructed. Metal-coordinated supramolecular nanoassemblies can modulate the tumor microenvironment (TME), thus facilitating the development of TME-responsive nanomedicines. More importantly, TME-responsive organic-inorganic hybrid nanomaterials can be constructed in vivo by exploiting the metal-coordinated self-assembly of a variety of functional ligands, which is a promising strategy for enhancing the tumor accumulation of theranostic molecules. In this review, recent advancements in the design and fabrication of metal-coordinated supramolecular nanomedicines for cancer theranostics are highlighted. These supramolecular compounds are classified according to the order in which the coordinated metal ions appear in the periodic table. Furthermore, the prospects and challenges of metal-coordinated supramolecular self-assemblies for both technical advances and clinical translation are discussed. In particular, the superiority of TME-responsive nanomedicines for in vivo coordinated self-assembly is elaborated, with an emphasis on strategies that enhance the accumulation of functional components in tumors for an ideal theranostic outcome.

Polyphenol-Containing Nanoparticles: Synthesis, Properties, and Therapeutic Delivery

Polyphenols, the phenolic hydroxyl group-containing organic molecules, are widely found in natural plants and have shown beneficial effects on human health. Recently, polyphenol-containing nanoparticles have attracted extensive research attention due to their antioxidation property, anticancer activity, and universal adherent affinity, and thus have shown great promise in the preparation, stabilization, and modification of multifunctional nanoassemblies for bioimaging, therapeutic delivery, and other biomedical applications. Additionally, the metal-polyphenol networks, formed by the coordination interactions between polyphenols and metal ions, have been used to prepare an important class of polyphenol-containing nanoparticles for surface modification, bioimaging, drug delivery, and disease treatments. By focusing on the interactions between polyphenols and different materials (e.g., metal ions, inorganic materials, polymers, proteins, and nucleic acids), a comprehensive review on the synthesis and properties of the polyphenol-containing nanoparticles is provided. Moreover, the remarkable versatility of polyphenol-containing nanoparticles in different biomedical applications, including biodetection, multimodal bioimaging, protein and gene delivery, bone repair, antibiosis, and cancer theranostics is also demonstrated. Finally, the challenges faced by future research regarding the polyphenol-containing nanoparticles are discussed.

Dual Modal Imaging-Guided Drug Delivery System for Combined Chemo-Photothermal Melanoma Therapy

PURPOSE

Malignant melanoma is one of the most devastating types of cancer with rapid relapse and low survival rate. Novel strategies for melanoma treatment are currently needed to enhance therapeutic efficiency for this disease. In this study, we fabricated a multifunctional drug delivery system that incorporates dacarbazine (DTIC) and indocyanine green (ICG) into manganese-doped mesoporous silica nanoparticles (MSN(Mn)) coupled with magnetic resonance imaging (MRI) and photothermal imaging (PI), for achieving the superior antitumor effect of combined chemo-photothermal therapy.

MATERIALS AND METHODS

MSN(Mn) were characterized in terms of size and structural properties, and drug loading and release efficiency MSN(Mn)-ICG/DTIC were analyzed by UV spectra. Photothermal imaging effect and MR imaging effect of MSN(Mn)-ICG/DTIC were detected by thermal imaging system and 3.0 T MRI scanner, respectively. Then, the combined chemo-phototherapy was verified in vitro and in vivo by morphological evaluation, ultrasonic and pathological evaluation.

RESULTS

The as-synthesized MSN(Mn) were characterized as mesoporous spherical nanoparticles with 125.57±5.96 nm. MSN(Mn)-ICG/DTIC have the function of drug loading-release which loading ratio of ICG and DTIC could reach to 34.25±2.20% and 50.00±3.24%, and 32.68±2.10% of DTIC was released, respectively. Manganese doping content could reach up to 65.09±2.55 wt%, providing excellent imaging capability in vivo which the corresponding relaxation efficiency was 14.33 mM-1s-1. And outstanding photothermal heating ability and stability highlighted the potential biomedical applicability of MSN(Mn)-ICG/DTIC to kill cancer cells. Experiments by A375 melanoma cells and tumor-bearing mice demonstrated that the compound MSN(Mn)-ICG/DTIC have excellent biocompatibility and our combined therapy platform delivered a superior antitumor effect compared to standalone treatment in vivo and in vitro.

CONCLUSION

Our findings demonstrate that composite MSN(Mn)-ICG/DTIC could serve as a multifunctional platform to achieve a highly effective chemo-photothermal combined therapy for melanoma treatment.

Phenolic-enabled nanotechnology: versatile particle engineering for biomedicine

Phenolics are ubiquitous in nature and have gained immense research attention because of their unique physiochemical properties and widespread industrial use. In recent decades, their accessibility, versatile reactivity, and relative biocompatibility have catalysed research in phenolic-enabled nanotechnology (PEN) particularly for biomedical applications which have been a major benefactor of this emergence, as largely demonstrated by polydopamine and polyphenols. Therefore, it is imperative to overveiw the fundamental mechanisms and synthetic strategies of PEN for state-of-the-art biomedical applications and provide a timely and comprehensive summary. In this review, we will focus on the principles and strategies involved in PEN and summarize the use of the PEN synthetic toolkit for particle engineering and the bottom-up synthesis of nanohybrid materials. Specifically, we will discuss the attractive forces between phenolics and complementary structural motifs in confined particle systems to synthesize high-quality products with controllable size, shape, composition, as well as surface chemistry and function. Additionally, phenolic's numerous applications in biosensing, bioimaging, and disease treatment will be highlighted. This review aims to provide guidelines for new scientists in the field and serve as an up-to-date compilation of what has been achieved in this area, while offering expert perspectives on PEN's use in translational research.

Iron-based nanoparticles for MR imaging-guided ferroptosis in combination with photodynamic therapy to enhance cancer treatment

Ferroptosis therapy, which applies ferroptotic inducers to produce lethal lipid peroxidation and induce the death of tumor cells, is regarded as a promising therapeutic strategy for cancer treatment. However, there is still a challenge regarding how to increase reactive oxygen species (ROS) accumulation in the tumor microenvironment (TME) to enhance antitumor efficacy. Herein, we designed a nanosystem coated with the FDA approved poly(lactic-co-glycolic acid) (PLGA) containing ferrous ferric oxide (Fe3O4) and chlorin E6 (Ce6) for synergistic ferroptosis-photodynamic anticancer therapy. The Fe3O4-PLGA-Ce6 nanosystem can dissociate in the acidic TME to release ferrous/ferric ions and Ce6. Then, the Fenton reaction between the released ferrous/ferric ions and intracellular excess hydrogen peroxide can occur to produce hydroxyl radicals (˙OH) and induce tumor cell ferroptosis. The released Ce6 can increase the generation and accumulation of ROS under laser irradiation to offer photodynamic therapy, which can boost ferroptosis in 4T1 cells. Moreover, magnetic monodisperse Fe3O4 loading provides excellent T2-weighted magnetic resonance imaging (MRI) properties. The Fe3O4-PLGA-Ce6 nanosystem possesses MRI ability and highly efficient tumor suppression with high biocompatibility in vivo due to the synergism of photodynamic and ferroptosis antitumor therapies.

Fe2O3 Nanoparticles Doped with Gd: Phase Transformations as a Result of Thermal Annealing

The aim of this work is to study the effect of the phase composition of the synthesized Fe2O3-Gd2O3 nanoparticles on the efficiency of using magnetic hyperthermia as a basis for experiments. This class of structures is one of the most promising materials for biomedical applications and magnetic resonance imaging. In the course of the study, the dynamics of phase transformations of nanoparticles Fe2O3 → Fe2O3/GdFeO3 → GdFeO3 were established depending on the annealing temperature. It has been determined that the predominance of the GdFeO3 phase in the structure of nanoparticles leads to an increase in their size from 15 to 40 nm. However, during experiments to determine the resistance to degradation and corrosion, it was found that GdFeO3 nanoparticles have the highest corrosion resistance. During the hyperthermal tests, it was found that a change in the phase composition of nanoparticles, as well as their size, leads to an increase in the heating rate of nanoparticles, which can be further used for practical purposes.

Ultrasmall Fe@Fe3O4 nanoparticles as T1-T2 dual-mode MRI contrast agents for targeted tumor imaging

Targeted T₁-T₂ MRI contrast agents, which can eliminate the difficulty of image matching across multiple imaging instruments and permit specific localization of lesions, are promising candidates for more accurate diagnosis of tumors. In this study, ultrasmall Fe@Fe₃O₄ nanoparticles were designed and synthesized as T₁-T₂ dual-mode MRI contrast agents for accurate tumor imaging. First, to investigate the influence of nanoparticle size, Fe@Fe₃O₄ nanoparticles with diameters of 4, 8, and 12 nm were prepared, among which the 8 nm 3-(3,4-dihydroxyphenyl)propionic acid (DHCA)-modified nanoparticles exhibited the optimal T₁-T₂ dual-mode MRI performance. Next, to develop a tumor-targeted contrast agent, the DHCA-Fe@Fe₃O₄ nanoparticles were conjugated with the F56 peptide, which targets the vascular endothelial growth factor receptor, and the resulting F56-DHCA-Fe@Fe₃O₄ nanoparticles were found to exhibit good T₁-T₂ dual-mode imaging and tumor-targeting performance both in vitro and in vivo, indicating the nanoparticles represent a new research tool for accurate tumor diagnosis.