Boosted Hyperthermia Therapy by Combined AC Magnetic and Photothermal Exposures in Ag/Fe3O4 Nanoflowers

Fundamentals and Applications of Dual-Frequency Magnetic Particle Spectroscopy: Review for Biomedicine and Materials Characterization

Superparamagnetic nanoparticles (MNP) offer exciting applications for engineering and biomedicine in imaging, diagnostics, and therapy upon magnetic excitation. Specifically, if excited at two distinct frequencies f1 and f2, MNP responds with magnetic intermodulation frequencies m·f1 ± n·f2 caused by their nonlinear magnetization. These mixing frequencies are highly specific for MNP properties, uniquely characterizing their presence. In this review, the fundamentals of frequency mixing magnetic detection (FMMD) as a special case of magnetic particle spectroscopy (MPS) are reviewed, elaborating its functional principle that enables a large dynamic range of detection of MNP. Mathematical descriptions derived from Langevin modeling and micromagnetic Monte-Carlo simulations show matching predictions. The latest applications of FMMD in nanomaterials characterization as well as diagnostic and therapeutic biomedicine are highlighted: analysis of the phase of the FMMD signal characterizes the magnetic relaxation of MNP, allowing to determine hydrodynamic size and binding state. Variation of excitation amplitudes or magnetic offset fields enables determining the size distribution of the particles' magnetic cores. This permits multiplex detection of polydisperse MNP in magnetic immunoassays, realized successfully for various biomolecular targets such as viruses, bacteria, proteins, and toxins. A portable magnetic reader enables portable immunodetection at point-of-care. Future applications toward theranostics are summarized and elaborated.

Chitosan-Functionalized Lithium Iron Oxide Nanoparticles for Magnetic Hyperthermia Applications

In this study, various compositions of α-Fe2O3, Li3xFe2-xO3, where x = 0.1, 0.3, and 0.5, along with chitosan (CTS)-coated Li1.5Fe1.5O3 nanomaterials (NMs), were synthesized using a sol-gel method. Rietveld refinement analysis indicated a predominance of the rhombohedral phase for lower Li-doped content (x = 0.1) and a transition to cubic crystal structures at higher Li-doped content (x = 0.3 and 0.5) within the host lattice. Field emission scanning electron microscopy (FE-SEM) images revealed irregular spherical morphologies, while transmission electron microscopy (TEM) images showed average particle sizes ranging from 19 to 40 nm across the various NMs. Superconducting quantum interference device (SQUID) analysis demonstrated a ferromagnetic nature with the highest saturation magnetization measured at 49.84 emu/g for Li1.5Fe1.5O3 NMs. X-ray photoelectron spectra (XPS) exhibited Fe 2p3/2 and Fe 2p1/2 peaks at 712.60 and 726.13 eV, respectively, Li 1s at 57.58 eV, and O 1s at 533.44 eV for the representative samples; these characteristic XPS peaks shifted to a lower binding energy for CTS-coated Li1.5Fe1.5O3 NMs. Hyperthermia studies demonstrated that the Li-doped samples reached a temperature range between 42 and 44 °C under an alternating current (AC) magnetic field applied at 167.6 to 335.2 Oe, with a constant frequency of 278 kHz. The specific absorption rate (SAR) was recorded as 265.11 W/g for Li1.5Fe1.5O3 and 153.48 W/g for CTS-coated Li1.5Fe1.5O3 NMs, both surpassing the SAR values of the other samples. Furthermore, various machine learning techniques were utilized to analyze how different synthesis conditions and material properties affected the heating efficiency and SAR values of the synthesized materials. The study also suggests an optimized set of guidelines and heuristics to enhance the heating performance and SAR values of these materials. Finally, magnetic CTS-coated Li1.5Fe1.5O3 NMs exhibited a higher cell viability, as confirmed by MTT assays conducted on the NRK 52 E normal cell line.

Nanoplatforms for Magnetic-Photo-Heating of Thermo-Resistant Tumor Cells: Singular Synergic Therapeutic Effects at Mild Temperature

A self-assemble amphiphilic diblock copolymer that can incorporate iron oxide nanocubes (IONCs) in chain-like assemblies as heat mediators for magnetic hyperthermia (MHT) and tuneable amounts of IR780 dye as agent for photothermal therapy (PTT) is developed. MHT-heating performance of photobeads in viscous media have the same heat performances in water at magnetic field conditions of clinical use. Thanks to IR780, the photobeads are activated by infrared laser light within the first biological window (808 nm) with a significant enhancement of photo-stability of IR780 enabling the raise of the temperature at therapeutic values during multiple PTT cycles and showing unchanged optical features up to 8 days. Moreover, the photobeads fluorescent signal is preserved once internalized by glioblastoma multiforme (GBM) cells. Peculiarly, the photobeads are used as toxic agents to eradicate thermo-resistant GBM cells at mild heat, as low as 41 °C, with MHT and PTT both of clinical use. Indeed, a high U87 GBM cell mortality percentage is obtained only with dual MHT/PTT while each single treatment dose not provide the same cytotoxic effects. Only for the combined treatment, the cell death mechanism is assigned to clear sign of apoptosis as observed by structural/morphological cell studies and enhanced lysosome permeability.

Magnetic Hyperthermia in Glioblastoma Multiforme Treatment

Glioblastoma multiforme (GBM) represents one of the most critical oncological diseases in neurological practice, being considered highly aggressive with a dismal prognosis. At a worldwide level, new therapeutic methods are continuously being researched. Magnetic hyperthermia (MHT) has been investigated for more than 30 years as a solution used as a single therapy or combined with others for glioma tumor assessment in preclinical and clinical studies. It is based on magnetic nanoparticles (MNPs) that are injected into the tumor, and, under the effect of an external alternating magnetic field, they produce heat with temperatures higher than 42 °C, which determines cancer cell death. It is well known that iron oxide nanoparticles have received FDA approval for anemia treatment and to be used as contrast substances in the medical imagining domain. Today, energetic, efficient MNPs are developed that are especially dedicated to MHT treatments. In this review, the subject's importance will be emphasized by specifying the number of patients with cancer worldwide, presenting the main features of GBM, and detailing the physical theory accompanying the MHT treatment. Then, synthesis routes for thermally efficient MNP manufacturing, strategies adopted in practice for increasing MHT heat performance, and significant in vitro and in vivo studies are presented. This review paper also includes combined cancer therapies, the main reasons for using these approaches with MHT, and important clinical studies on human subjects found in the literature. This review ends by describing the most critical challenges associated with MHT and future perspectives. It is concluded that MHT can be successfully and regularly applied as a treatment for GBM if specific improvements are made.

Integration of photomagnetic bimodal imaging to monitor an autogenous exosome loaded platform: unveiling strong targeted retention effects for guiding the photothermal and magnetothermal therapy in a mouse prostate cancer model

BACKGROUND

Prostate cancer (PCa) is the most prevalent cancer among males, emphasizing the critical need for precise diagnosis and treatment to enhance patient prognosis. Recent studies have extensively utilized urine exosomes from patients with cancer for targeted delivery. This study aimed to employ highly sensitive magnetic particle imaging (MPI) and fluorescence molecular imaging (FMI) to monitor the targeted delivery of an exosome-loaded platform at the tumour site, offering insights into a potential combined photothermal and magnetic thermal therapy regime for PCa.

RESULTS

MPI and FMI were utilized to monitor the in vivo retention performance of exosomes in a prostate tumour mouse model. The exosome-loaded platform exhibited robust homologous targeting ability during imaging (SPIONs@EXO-Dye:66·48%±3·85%; Dye-SPIONs: 34·57%±7·55%, **P<0·01), as verified by in vitro imaging and in vitro tissue Prussian blue staining.

CONCLUSIONS

The experimental data underscore the feasibility of using MPI for in vivo PCa imaging. Furthermore, the exosome-loaded platform may contribute to the precise diagnosis and treatment of PCa.

"Nano-egg" superstructures of hydrophobic nanocrystals dispersed in water

In this feature article, we use hydrophobic ferrite (Fe3O4) nanocrystal shells filled with Au nanocrystals self-assembled into 3D superlattices and dispersed in water. These superstructures act as nano-heaters. The stability of such superstructures is very high, even for several years, when stored at room temperature. When subjected to an electron beam, the inverted structure of Fe3O4 structures is gradually dissolved due to the formation of hydrated electrons and hydroxyl radicals.

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.

NIR and magnetism dual-response multi-core magnetic vortex nanoflowers for boosting magneto-photothermal cancer therapy

Due to the relatively low efficiency of magnetic hyperthermia and photothermal conversion, it is rather challenging for magneto-photothermal nanoagents to be used as an effective treatment during tumor hyperthermal therapy. The advancement of magnetic nanoparticles exhibiting a vortex-domain structure holds great promise as a viable strategy to enhance the application performance of conventional magnetic nanoparticles while retaining their inherent biocompatibility. Here, we report the development of Mn0.5Zn0.5Fe2O4 nanoflowers with ellipsoidal magnetic cores, and show them as effective nanoagents for magneto-photothermal synergistic therapy. Comparative studies were conducted on the heating performance of anisometric Mn0.5Zn0.5Fe2O4 (MZF) nanoparticles, including nanocubes (MZF-C), hollow spheres (MZF-HS), nanoflowers consisting of ellipsoidal magnetic cores (MZF-NFE), and nanoflowers consisting of needle-like magnetic cores (MZF-NFN). MZF-NFE exhibits an intrinsic loss parameter (ILP) of up to 15.3 N h m2 kg-1, which is better than that of commercial equivalents. Micromagnetic simulations reveal the magnetization configurations and reversal characteristics of the various MZF shapes. Additionally, all nanostructures displayed a considerable photothermal conversion efficiency rate of more than 18%. Our results demonstrated that by combining the dual exposure of MHT and PTT for hyperthermia treatments induced by MZF-NFE, BT549, MCF-7, and 4T1 cell viability can be significantly decreased by ∼95.7% in vitro.

Self-propelling bacteria-based magnetic nanoparticles (BacMags) for targeted magnetic hyperthermia therapy against hypoxic tumors

Magnetic hyperthermia-based cancer therapy (MHCT) holds great promise as a non-invasive approach utilizing heat generated by an alternating magnetic field for effective cancer treatment. For an efficacious therapeutic response, it is crucial to deliver therapeutic agents selectively at the depth of tumors. In this study, we present a new strategy using the naturally occurring tumor-colonizing bacteria Escherichia coli (E. coli) as a carrier to deliver magnetic nanoparticles to hypoxic tumor cores for effective MHCT. Self-propelling delivery agents, "nano-bacteriomagnets" (BacMags), were developed by incorporating anisotropic magnetic nanocubes into E. coli which demonstrated significantly improved hyperthermic performance, leading to an impressive 85% cell death in pancreatic cancer. The in vivo anti-cancer response was validated in a syngeneic xenograft model with a 50% tumor inhibition rate within 20 days and a complete tumor regression within 30 days. This proof-of-concept study demonstrates the potential of utilizing anaerobic bacteria for the delivery of magnetic nanocarriers as a smart therapeutic approach for enhanced MHCT.

Advancements in Photothermal Therapy Using Near-Infrared Light for Bone Tumors

Bone tumors, particularly osteosarcoma, are prevalent among children and adolescents. This ailment has emerged as the second most frequent cause of cancer-related mortality in adolescents. Conventional treatment methods comprise extensive surgical resection, radiotherapy, and chemotherapy. Consequently, the management of bone tumors and bone regeneration poses significant clinical challenges. Photothermal tumor therapy has attracted considerable attention owing to its minimal invasiveness and high selectivity. However, key challenges have limited its widespread clinical use. Enhancing the tumor specificity of photosensitizers through targeting or localized activation holds potential for better outcomes with fewer adverse effects. Combinations with chemotherapies or immunotherapies also present avenues for improvement. In this review, we provide an overview of the most recent strategies aimed at overcoming the limitations of photothermal therapy (PTT), along with current research directions in the context of bone tumors, including (1) target strategies, (2) photothermal therapy combined with multiple therapies (immunotherapies, chemotherapies, and chemodynamic therapies, magnetic, and photodynamic therapies), and (3) bifunctional scaffolds for photothermal therapy and bone regeneration. We delve into the pros and cons of these combination methods and explore current research focal points. Lastly, we address the challenges and prospects of photothermal combination therapy.

Recent advances in functionalized ferrite nanoparticles: From fundamentals to magnetic hyperthermia cancer therapy

Cancers are fatal diseases that lead to most death of human beings, which urgently require effective treatments methods. Hyperthermia therapy employs magnetic nanoparticles (MNPs) as heating medium under external alternating magnetic field. Among various MNPs, ferrite nanoparticles (FNPs) have gained significant attention for hyperthermia therapy due to their exceptional magnetic properties, high stability, favorable biological compatibility, and low toxicity. The utilization of FNPs holds immense potential for enhancing the effectiveness of hyperthermia therapy. The main hurdle for hyperthermia treatment includes optimizing the heat generation capacity of FNPs and controlling the local temperature of tumor region. This review aims to comprehensively evaluate the magnetic hyperthermia treatment (MHT) of FNPs, which is accomplished by elucidating the underlying mechanism of heat generation and identifying influential factors. Based upon fundamental understanding of hyperthermia of FNPs, valuable insights will be provided for developing efficient nanoplatforms with enhanced accuracy and magnetothermal properties. Additionally, we will also survey current research focuses on modulating FNPs' properties, external conditions for MHT, novel technical methods, and recent clinical findings. Finally, current challenges in MHT with FNPs will be discussed while prospecting future directions.

Synergized photothermal therapy and magnetic field induced hyperthermia via bismuthene for lung cancer combinatorial treatment

Thanks to its intrinsic properties, two-dimensional (2D) bismuth (bismuthene) can serve as a multimodal nanotherapeutic agent for lung cancer acting through multiple mechanisms, including photothermal therapy (PTT), magnetic field-induced hyperthermia (MH), immunogenic cell death (ICD), and ferroptosis. To investigate this possibility, we synthesized bismuthene from the exfoliation of 3D layered bismuth, prepared through a facile method that we developed involving surfactant-assisted chemical reduction, with a specific focus on improving its magnetic properties. The bismuthene nanosheets showed high in vitro and in vivo anti-cancer activity after simultaneous light and magnetic field exposure in lung adenocarcinoma cells. Only when light and magnetic field are applied together, we can achieve the highest anti-cancer activity compared to the single treatment groups. We have further shown that ICD-dependent mechanisms were involved during this combinatorial treatment strategy. Beyond ICD, bismuthene-based PTT and MH also resulted in an increase in ferroptosis mechanisms both in vitro and in vivo, in addition to apoptotic pathways. Finally, hemolysis in human whole blood and a wide variety of assays in human peripheral blood mononuclear cells indicated that the bismuthene nanosheets were biocompatible and did not alter immune function. These results showed that bismuthene has the potential to serve as a biocompatible platform that can arm multiple therapeutic approaches against lung cancer.

Emergence of magnetic nanoparticles in photothermal and ferroptotic therapies

With their distinctive physicochemical features, nanoparticles have gained recognition as effective multifunctional tools for biomedical applications, with designs and compositions tailored for specific uses. Notably, magnetic nanoparticles stand out as first-in-class examples of multiple modalities provided by the iron-based composition. They have long been exploited as contrast agents for magnetic resonance imaging (MRI) or as anti-cancer agents generating therapeutic hyperthermia through high-frequency magnetic field application, known as magnetic hyperthermia (MHT). This review focuses on two more recent applications in oncology using iron-based nanomaterials: photothermal therapy (PTT) and ferroptosis. In PTT, the iron oxide core responds to a near-infrared (NIR) excitation and generates heat in its surrounding area, rivaling the efficiency of plasmonic gold-standard nanoparticles. This opens up the possibility of a dual MHT + PTT approach using a single nanomaterial. Moreover, the iron composition of magnetic nanoparticles can be harnessed as a chemotherapeutic asset. Degradation in the intracellular environment triggers the release of iron ions, which can stimulate the production of reactive oxygen species (ROS) and induce cancer cell death through ferroptosis. Consequently, this review emphasizes these emerging physical and chemical approaches for anti-cancer therapy facilitated by magnetic nanoparticles, combining all-in-one functionalities.

Scale-up approach for the preparation of magnetic ferrite nanocubes and other shapes with benchmark performance for magnetic hyperthermia applications

Magnetic nanoparticles are increasingly used in medical applications, including cancer treatment by magnetic hyperthermia. This protocol describes a solvothermal-based process to prepare, at the gram scale, ferrite nanoparticles with well-defined shape, i.e., nanocubes, nanostars and other faceted nanoparticles, and with fine control of structural/magnetic properties to achieve point-of-reference magnetic hyperthermia performance. This straightforward method comprises simple steps: (i) making a homogeneous alcoholic solution of a surfactant and an alkyl amine; (ii) adding an organometallic metal precursor together with an aldehyde molecule, which acts as the key shape directing agent; and (iii) reacting the mixture in an autoclave for solvothermal crystallization. The shape of the ferrite nanoparticles can be controlled by the structure of the aldehyde ligand. Benzaldehyde and its aromatic derivatives favor the formation of cubic ferrite nanoparticles while aliphatic aldehydes result in spherical nanoparticles. The replacement of the primary amine, used in the nanocubes synthesis, with a secondary/tertiary amine results in nanoparticles with star-like shape. The well-defined control in terms of shape, narrow size distribution (below 5%), compositional tuning and crystallinity guarantees the preparation, at the gram scale, of nanocubes/star-like nanoparticles that possess, under magnetic field conditions of clinical use, specific adsorption rates comparable to or even superior to those obtained through thermal decomposition methods, which are typically prepared at the milligram scale. Here, gram-scale nanoparticle products with benchmark features for magnetic hyperthermia applications can be prepared in ~10 h with an average level of expertise in chemistry.

Role of site selective substitution, magnetic parameter tuning, and self heating in magnetic hyperthermia application: Eu-doped magnetite nanoparticles

Various researchers have provided considerable insight into the fundamental mechanisms behind the power absorption of single-domain magnetic nanoparticles (MNPs) in magnetic hyperthermia applications. However, the role of all parameters pertinent to magnetic relaxation continues to be debated. Herein, to explore the role of magnetic anisotropy with the site selective substitution related to magnetic relaxation has generally been missing, which is critically essential in respective of hyperthermia treatment. Our study unravels contradictory results of rare earth (RE) interaction effects in ferrite to that of recently reported literature. Despite this, rare earth atoms have unique f-block properties, which significantly impact the magnetic anisotropy as well as the relaxation mechanism. Here, we use appropriate Eu doping concentration in magnetite and analyze its effect on the matrix. Furthermore, a positive SAR can effectively reduce the relative dose assigned to a patient to a minimal level. This study indicates that the introduction of Eu ion positively influenced the heating efficiency of the examined magnetite systems.

Angiopep-2-decorated titanium-alloy core-shell magnetic nanoparticles for nanotheranostics and medical imaging

The poor permeability of therapeutic agents across the blood-brain barrier and blood-tumor barrier is a significant barrier in glioma treatment. Low-density lipoprotein receptor-related protein (LRP-1) recognises a dual-targeting ligand, angiopep-2, which is overexpressed in the BBB and gliomas. Here, we have synthesized Ti@FeAu core-shell nanoparticles conjugated with angiopep-2 (Ti@FeAu-Ang nanoparticles) to target glioma cells and treat brain cancer via hyperthermia produced by a magnetic field. Our results confirmed that Ti@FeAu core-shell nanoparticles were superparamagnetic, improved the negative contrast effect on glioma, and exhibited a temperature elevation of 12° C upon magnetic stimulation, which implies potential applications in magnetic resonance imaging (MRI) and hyperthermia-based cancer therapy. Angiopep-2-decorated nanoparticles exhibited higher cellular uptake by C6 glioma cells than by L929 fibroblasts, demonstrating selective glioma targeting and improved cytotoxicity up to 85% owing to hyperthermia produced by a magnetic field. The in vivo findings demonstrated that intravenous injection of Ti@FeAu-Ang nanoparticles exhibited a 10-fold decrement in tumor volume compared to the control group. Furthermore, immunohistochemical analysis of Ti@FeAu-Ang nanoparticles showed that coagulative necrosis of tumor tissues and preliminary safety analysis highlighted no toxicity to the haematological system, after Ti@FeAu-Ang nanoparticle-induced hyperthermia treatment.

Multifunctional Au nano-bridged nanogap probes as ICP-MS/SERS dual-signal tags and signal amplifiers for bacteria discriminating, quantitative detecting and photothermal bactericidal activity

Ultra-sensitive detection of pathogenic bacteria is of great significance in the early stage of bacterial infections and treatment. In this work, we report a novel strategy using multifunctional Au nano-bridged nanogap nanoparticles (Au NNPs)-based sandwich nanocomposites, that made of Concanavalin A-conjugated Fe₃O₄@SiO₂ NPs (ConA-Fe₃O₄@SiO₂ NPs)/bacteria/aptamer-modified Au NNPs (apt-Au NNPs), for bacteria discrimination and quantitative detection by surface-enhanced Raman scattering (SERS) and inductively coupled plasma mass spectrometry (ICP-MS), and subsequently photothermal antibacterial assay. The sandwich nanocomposite consists of ConA-Fe₃O₄@SiO₂ NPs to magnetically enrich and photothermal killing bacteria, and dual-signal tags of apt-Au NNPs for both SERS sensing and ICP-MS quantification. This strategy can specifically distinguish different kinds of pathogenic bacteria, and provided a good linear relationship of Staphylococcus aureus (S. aureus) in the range from 50 to 10⁴ CFU/mL with a detection limit of 11 CFU/mL, as well as realized ultralow amounts of bacterial detection in serum sample with high accuracy. Based on the quantitative detection, high antibacterial efficiency was monitored by ICP-MS. Overall, the established method combines bacteria discrimination, quantitative detection, and photothermal elimination with a simple and rapid process, which provides a novel way for the early diagnosis and treatment of bacterial infection.

Tailoring nanoparticles design for enhanced heating efficiency and improved magneto-chemo therapy for glioblastoma

Development of multifunctional magnetic nanomaterials (MNPs) with improved heat-generating capabilities and effective combination with localized chemotherapy has emerged as a promising therapeutic regime for solid tumors like glioblastoma. In this regard, the shape-dependent hyperthermic and chemo-therapeutic potential of nanomaterials, has not been extensively explored. Here we present, development of various morphological designs of MNPs including spherical, clusters, rods and cubic; to compare the effect of shape on tuning the properties of MNPs that are relevant to many potential biomedical applications like drug delivery, cellular uptake and heat generation. The study includes extensive comparison of morpho-structural characteristics, size distributions, chemical composition, surface area measurements and magnetic properties of the variable shaped MNPs. Further the heating efficiencies in aqueous and cellular environments and heat triggered drug release profiles for successful magneto-chemotherapy were compared among all in-house synthesized MNPs. Under biosafety limit considerations given by Hergt's limit (H*f value <5 × 10⁹ Am^-1 s^-1), cuboidal shaped MNPs demonstrated highest heating efficiency owing to magnetosome-like chain formation along with sustained drug release profile as compared to other synthesized MNPs. The mechanism of cancer cell death mediated via magneto-chemotherapy was elucidated to be the oxidative stress-mediated apoptotic cell death pathway. In vivo studies further demonstrated complete tumor regression only in the magneto-chemotherapy treated group. These findings suggest the potential of combinatorial therapy to overcome the clinical limitations of the independent therapies for advanced thermotherapy of glioblastoma.

Supraballs as spherical solid 3D superlattices of hydrophobic nanocrystals dispersed in water: nanoarchitectonics and properties

Herein, we use a water-dispersive 3D suprastructure of ferrite (Fe₃O₄) nanocrystals called supraballs. They are solid spherical assemblies of hydrophobic nanocrystals with a rather low Young's modulus compared to similar 3D superlattices deposited on a substrate. Using atomic force microscopy methods, their nanomechanical properties are measured, which show small flexibility and deformation. This suprastructure behaves as a nanoheater and remains self-assembled after internalization in cancer cells. Furthermore, when subjected to light, the percentage of dead cells compared to the nanocrystals used as building blocks and dispersed in the solution increases.

Magnetic Anisotropy of Individual Nanomagnets Embedded in Biological Systems Determined by Axi-asymmetric X-ray Transmission Microscopy

Over the past few years, the use of nanomagnets in biomedical applications has increased. Among others, magnetic nanostructures can be used as diagnostic and therapeutic agents in cardiovascular diseases, to locally destroy cancer cells, to deliver drugs at specific positions, and to guide (and track) stem cells to damaged body locations in regenerative medicine and tissue engineering. All these applications rely on the magnetic properties of the nanomagnets which are mostly determined by their magnetic anisotropy. Despite its importance, the magnetic anisotropy of the individual magnetic nanostructures is unknown. Currently available magnetic sensitive microscopic methods are either limited in spatial resolution or in magnetic field strength or, more relevant, do not allow one to measure magnetic signals of nanomagnets embedded in biological systems. Hence, the use of nanomagnets in biomedical applications must rely on mean values obtained after averaging samples containing thousands of dissimilar entities. Here we present a hybrid experimental/theoretical method capable of working out the magnetic anisotropy constant and the magnetic easy axis of individual magnetic nanostructures embedded in biological systems. The method combines scanning transmission X-ray microscopy using an axi-asymmetric magnetic field with theoretical simulations based on the Stoner-Wohlfarth model. The validity of the method is demonstrated by determining the magnetic anisotropy constant and magnetic easy axis direction of 15 intracellular magnetite nanoparticles (50 nm in size) biosynthesized inside a magnetotactic bacterium.

Polymer modified magnetic-luminescent nanocomposites for combined optical imaging and magnetic fluid hyperthermia in cancer therapy: analysis of Mn2+ doping for enhanced heating effect, hemocompatibility and biocompatibility

Magnetic Mn_xFe_3-xO₄ nanoparticles and polymer coated magnetic-luminescent Mn_xFe_3-xO₄@(Y,Dy/Eu)VO₄ nanocomposites were prepared to study their comparative heat generation efficiency and biocompatibilities. Cubic crystalline phases were obtained for the nanoparticles and cubic-tetragonal biphasic phases were observed for the nanocomposites. The successful doping of Mn²⁺ was also confirmed by inductively coupled plasma optical emission spectroscopy. The compositions and the surface modification chemistry were confirmed by infrared spectroscopy. The formation of near-spherical and cubic/cuboid nanoparticles was observed from electron microscopy. Comparative analysis of induction heating efficiencies and magnetization values of the synthesized materials was performed for the samples. The samples showed an efficient heating effect under the influence of alternating magnetic field strengths - 3.05 × 10⁶ kA m^-1 s^-1 and 4.58 × 10⁶ kA m^-1 s^-1. A higher Mn²⁺ content was found to possess higher magnetization and perform better in heat generation. The nanocomposites give brilliant color emission on excitation using ultraviolet wavelengths - 300 and 315 nm. Their hydrodynamic radii and zeta potential values indicate good stability of the dispersions. Hemocompatibility studies were carried out to ascertain the effect on red blood cells. The materials were also found to exhibit excellent biocompatibility towards HeLa cell lines. This article will provide a new insight into the use of Mn_xFe_3-xO₄ based nanocomposites for magnetic fluid hyperthermia in cancer therapy.

Fe3 O4 @Au@Cu2-x S Heterostructures Designed for Tri-Modal Therapy: Photo- Magnetic Hyperthermia and 64 Cu Radio-Insertion

Here, the synthesis and proof of exploitation of three-material inorganic heterostructures made of iron oxide-gold-copper sulfide (Fe₃ O₄ @Au@Cu_2-x S) are reported. Starting with Fe₃ O₄ -Au dumbbell heterostructure as seeds, a third Cu_2-x S domain is selectively grown on the Au domain. The as-synthesized trimers are transferred to water by a two-step ligand exchange procedure exploiting thiol-polyethylene glycol to coordinate Au and Cu_2-x S surfaces and polycatechol-polyethylene glycol to bind the Fe₃ O₄ surface. The saline stable trimers possess multi-functional properties: the Fe₃ O₄ domain, of appropriate size and crystallinity, guarantees optimal heating losses in magnetic hyperthermia (MHT) under magnetic field conditions of clinical use. These trimers have indeed record values of specific adsorption rate among the inorganic-heterostructures so far reported. The presence of Au and Cu_2-x S domains ensures a large adsorption which falls in the first near-infrared (NIR) biological window and is here exploited, under laser excitation at 808 nm, to produce photo-thermal heat alone or in combination with MHT obtained from the Fe₃ O₄ domain. Finally, an intercalation protocol with radioactive ⁶⁴ Cu ions is developed on the Cu_2-x S domain, reaching high radiochemical yield and specific activity making the Fe₃ O₄ @Au@Cu_2-x S trimers suitable as carriers for ⁶⁴ Cu in internal radiotherapy (iRT) and traceable by positron emission tomography (PET).

Magneto-optical hyperthermia agents based on probiotic bacteria loaded with magnetic and gold nanoparticles

Probiotic bacteria were used as carriers of metallic nanoparticles to develop innovative oral agents for hyperthermia cancer therapy. Two synthetic strategies were used to produce the different therapeutic agents. First, the probiotic bacterium Lactobacillus fermentum was simultaneously loaded with magnetic (MNPs) and gold nanoparticles (AuNPs) of different morphologies to produce AuNP + MNP-bacteria systems with both types of nanoparticles arranged in the same layer of bacterial exopolysaccharides (EPS). In the second approach, the probiotic was first loaded with AuNP to form AuNP-bacteria and subsequently loaded with MNP-EPS to yield AuNP-bacteria-EPS-MNP with the MNP and AuNP arranged in two different EPS layers. This second strategy has never been reported and exploits the presence of EPS-EPS recognition which allows the layer-by-layer formation of structures on the bacteria external wall. The AuNP + MNP-bacteria and AuNP-bacteria-EPS-MNP samples were characterized by scanning (SEM) and transmission electron microscopy (TEM), and UV-vis spectroscopy. The potential of these two heterobimetallic systems as magnetic hyperthermia or photothermal therapy agents was assessed, validating their capacity to produce heat either during exposure to an alternating magnetic field or near-infrared laser light. The probiotic Lactobacillus fermentum has already been proposed as an oral drug carrier, able to overcome the stomach medium and deliver drugs to the intestines, and it is actually marketed as an oral supplement to reinforce the gut microbiota, thus, our results open the way for the development of novel therapeutic strategies using these new heterobimetallic AuNP/MNP-bacteria systems in the frame of gastric diseases, using them, for example, as oral agents for cancer treatment with magnetic hyperthermia and photothermal therapy.

A Review: Potential Application and Outlook of Photothermal Therapy in Oral Cancer Treatment

As one of the most common malignant tumors, oral cancer threatens people's health worldwide. However, traditional therapies, including surgery, radiotherapy, and chemotherapy can't meet the requirement of cancer cure. Photothermal therapy (PTT) has attracted widespread attentions for its advantages of the noninvasive process, few side effects, and promising tumor ablation. Up to now, three types of photothermal agents (PTAs) have been widely employed in oral cancer therapies, which involve metallic materials, carbon-based materials, and organic materials. Previous research mainly introduced hybrid materials due to benefits from the synergistic effect of multiple functions. In this review, we present the advancement of each type PTAs for oral cancer treatment in recent years. In each part, we introduce the properties and synthesis of each PTA, summarize the current studies, and analyze their potential applications. Furthermore, we discuss the status quo and the deficiencies hindering the clinical application of PTT, based on which gives the perspective of its future developing directions.

A Simple and Efficient Embolization-Combined Therapy for Solid Tumors by Smart Poly(amino acid)s Nanocomposites

Interventional embolization and minimally invasive thermal ablation are common clinical methods for treatment of unresectable solid tumors, but they both have many insurmountable disadvantages. Inspired by pH-responsive drug delivery systems, we report the tumor microenvironment-gelled nanocomposites with poly[(l-glutamic acid-ran-l-tyrosine)-b-l-threonine-b-l-cysteine]s (PGTTCs) coating nanoparticles (NPs, Au or Fe₃O₄) for noninterventional targeted embolization combined with noninvasive thermal ablation therapy of solid tumors by intravenous injection without catheter use. The results of the animal trial in vivo with tumor-bearing mice and rabbits showed superior targeted embolization and therapy and fluorescence/single-photon emission computed tomography/magnetic resonance multimodal imaging effects. Tumors treated with NPs@PGTTCs were shrunken and necrotized within 30 days, the long-term survival rate was more than 80%, and the same effects can be achieved within 15 days when combined with thermal ablation. The method is so simple and efficient for many hard-to-treat tumors within an acidic microenvironment, which is not only a great improvement and innovation in tumor theranostics but also an important development in nanomedicine.

Alternating magnetic field and NIR energy conversion on magneto-plasmonic Fe3O4@APTES–Ag heterostructures with SERS detection capability and antimicrobial activity

Fe3O4@APTES–Ag is a potential multipurpose platform for biological applications such as photomagnetic therapies, analytic probes exploiting the SERS effect and antibacterial activity.

Smart-Polypeptide-Coated Mesoporous Fe3O4 Nanoparticles: Non-Interventional Target-Embolization/Thermal Ablation and Multimodal Imaging Combination Theranostics for Solid Tumors

Tumor theranostics hold great potential for personalized medicine in the future, and transcatheter arterial embolization (TAE) is an important clinical treatment for unresectable or hypervascular tumors. In order to break the limitation, simplify the procedure of TAE, and achieve ideal combinatorial theranostic capability, here, a kind of triblock-polypeptide-coated perfluoropentane-loaded mesoporous Fe₃O₄ nanocomposites (PFP-m-Fe₃O₄@PGTTCs) were prepared for non-interventional target-embolization, magnetic hyperthermia, and multimodal imaging combination theranostics of solid tumors. The results of systematic animal experiments by H22-tumor-bearing mice and VX2-tumor-bearing rabbits in vivo indicated that PFP-m-Fe₃O₄@PGTTC-6.3 has specific tumor accumulation and embolization effects. The tumors' growth has been inhibited and the tumors disappeared 4 weeks and ≤15 days post-injection with embolization and magnetic hyperthermia combination therapy, respectively. The results also showed an excellent effect of magnetic resonance/ultrasound/SPECT multimodal imaging. This pH-responsive non-interventional embolization combinatorial theranostics system provides a novel embolization and multifunctional theranostic candidate for solid tumors.

Magnetic nanoparticles and clusters for magnetic hyperthermia: optimizing their heat performance and developing combinatorial therapies to tackle cancer

Magnetic hyperthermia (MHT) is a therapeutic modality for the treatment of solid tumors that has now accumulated more than 30 years of experience. In the ongoing MHT clinical trials for the treatment of brain and prostate tumors, iron oxide nanoparticles are employed as intra-tumoral MHT agents under a patient-safe 100 kHz alternating magnetic field (AMF) applicator. Although iron oxide nanoparticles are currently approved by FDA for imaging purposes and for the treatment of anemia, magnetic nanoparticles (MNPs) designed for the efficient treatment of MHT must respond to specific physical-chemical properties in terms of magneto-energy conversion, heat dose production, surface chemistry and aggregation state. Accordingly, in the past few decades, these requirements have boosted the development of a new generation of MNPs specifically aimed for MHT. In this review, we present an overview on MNPs and their assemblies produced via different synthetic routes, focusing on which MNP features have allowed unprecedented heating efficiency levels to be achieved in MHT and highlighting nanoplatforms that prevent magnetic heat loss in the intracellular environment. Moreover, we review the advances on MNP-based nanoplatforms that embrace the concept of multimodal therapy, which aims to combine MHT with chemotherapy, radiotherapy, immunotherapy, photodynamic or phototherapy. Next, for a better control of the therapeutic temperature at the tumor, we focus on the studies that have optimized MNPs to maintain gold-standard MHT performance and are also tackling MNP imaging with the aim to quantitatively assess the amount of nanoparticles accumulated at the tumor site and regulate the MHT field conditions. To conclude, future perspectives with guidance on how to advance MHT therapy will be provided.

Sensitive MnFe2O4-Ag hybrid nanoparticles with photothermal and magnetothermal properties for hyperthermia applications

In this study, we present an experiment showing that designing multifunctional MnFe2O4-Ag nanoparticles to act as a dual hyperthermia agent is an efficient route for enhancing their heating ability. Interestingly, the specific absorption rate of the heteromeric MnFe2O4-Ag nanoparticles increased 2.7 times under simultaneous irradiation of a 100 Oe magnetic field and 0.14 W cm-2 laser compared to the action by the magnetic field alone, and more interestingly, is 30% higher than the sum of the two individual actions. The synergistic benefit of the magneto- and photo-thermal properties of the heteromeric structure can reduce the strengths of the magnetic field and laser intensities as well as their irradiation time to levels lower than those required in their hyperthermia applications individually. In vitro cytotoxicity analysis performed on HepG2 liver cancer and Hela cervical cancer cell lines showed that IC50 values were 83 ± 5.6 μg mL-1 (for HepG2) and 122.6 ± 19.8 μg mL-1 (for Hela cells) after 48 h of incubation, therefore, the nanoparticles are moderately cytotoxic and nontoxic to HepG2 and Hela cells, respectively; which offers the potential of safe therapy.

Polypyrrole-Coated Magnetite Vortex Nanoring for Hyperthermia-Boosted Photothermal/Magnetothermal Tumor Ablation Under Photoacoustic/Magnetic Resonance Guidance

Photothermal/magnetothermal-based hyperthermia cancer therapy techniques have been widely investigated, and associated nanotechnology-assisted treatments have shown promising clinical potentials. However, each method has some limitations, which have impeded extensive applications. For example, the penetration ability of the photothermal is not satisfactory, while the heating efficiency of the magnetothermal is very poor. In this study, a novel magnetite vortex nanoring nanoparticle-coated with polypyrrole (denoted as nanoring Fe3O4@PPy-PEG) was first synthesized and well-characterized. By combining photothermal and magnetothermal effects, the performance of the dual-enhanced hyperthermia was significantly improved, and was thoroughly examined in this study. Benefiting from the magnetite vortex nanoring and polypyrrole, Fe3O4@PPy-PEG showed excellent hyperthermia effects (SAR = 1,648 Wg-1) when simultaneously exposed to the alternating magnetic field (300 kHz, 45 A) and near-infrared (808 nm, 1 W cm-2) laser. What is more, nanoring Fe3O4@PPy-PEG showed a much faster heating rate, which can further augment the antitumor effect by incurring vascular disorder. Besides, Fe3O4@PPy-PEG exhibited a high transverse relaxation rate [60.61 mM-1 S-1 (Fe)] at a very low B0 field (0.35 T) and good photoacoustic effect. We believe that the results obtained herein can significantly promote the development of multifunctional nanoparticle-mediated magnetic and photo induced efficient hyperthermia therapy.

Iron Oxide Nanorings and Nanotubes for Magnetic Hyperthermia: The Problem of Intraparticle Interactions

Magnetic interactions can play an important role in the heating efficiency of magnetic nanoparticles. Although most of the time interparticle magnetic interactions are a dominant source, in specific cases such as multigranular nanostructures intraparticle interactions are also relevant and their effect is significant. In this work, we have prepared two different multigranular magnetic nanostructures of iron oxide, nanorings (NRs) and nanotubes (NTs), with a similar thickness but different lengths (55 nm for NRs and 470 nm for NTs). In this way, we find that the NTs present stronger intraparticle interactions than the NRs. Magnetometry and transverse susceptibility measurements show that the NTs possess a higher effective anisotropy and saturation magnetization. Despite this, the AC hysteresis loops obtained for the NRs (0-400 Oe, 300 kHz) are more squared, therefore giving rise to a higher heating efficiency (maximum specific absorption rate, SARmax = 110 W/g for the NRs and 80 W/g for the NTs at 400 Oe and 300 kHz). These results indicate that the weaker intraparticle interactions in the case of the NRs are in favor of magnetic hyperthermia in comparison with the NTs.

Selective Detection of Cancer Cells Using Magnetic Nanowires

The main bottleneck for implementing magnetic nanowires (MNWs) in cell-biology research for multimodal therapeutics is the inapplicability of the current state of the art for selective detection and stimulation of MNWs. Here, we introduce a methodology for selective detection of MNWs in platforms that have multiple magnetic signals, such as future multimodal therapeutics. After characterizing the signatures of MNWs, MNWs were surface-functionalized and internalized into canine osteosarcoma (OSCA-8) cancer cells for cell labeling, manipulation, and separation. We also prepared and characterized magnetic biopolymers as multimodal platforms for future use in controlling the movement, growth, and division of cancer cells. First, it is important to have methods for distinguishing the magnetic signature of the biopolymer from the magnetically labeled cells. For this purpose, we use the projection method to selectively detect and demultiplex the magnetic signatures of MNWs inside cells from those inside magnetic biopolymers. We show that tailoring the irreversible switching field of MNWs by tuning their coercivity is a highly effective approach for generating distinct magnetic biolabels for selective detection of cancer cells. These findings open up new possibilities for selective stimulation of MNWs in multimodal therapeutic platforms for drug delivery, hyperthermia cancer therapy, and mitigating cancer cell movement and proliferation.

Magnetoliposomes: recent advances in the field of controlled drug delivery

INTRODUCTION

Magnetoliposomes have gained increasing attention as delivery systems, as they surpass many limitations associated with liposomes. The combination with magnetic nanoparticles provides a means for development of multimodal and multifunctional theranostic agents that enable on-demand drug release and real-time monitoring of therapy.

AREAS COVERED

Recently, several magnetoliposome structures have been reported to ensure efficient transport and delivery of therapeutics, while improving magnetic properties. Besides, novel techniques have been introduced to improve on-demand release, as well as to achieve sequential release of different therapeutic agents. This review presents the major types and methods of preparation of magnetoliposomes, and discusses recent strategies in the trigger of drug release, development of theranostic formulations, and delivery of drugs and biological entities.

EXPERT OPINION

Despite significant advances in efficient drug delivery, current literature lacks an assessment of formulations as theranostic agents and complementary techniques to optimize thermotherapy efficiency. Plasmonic magnetoliposomes are highly promising multimodal and multifunctional systems, providing the required design versatility to optimize theranostic capabilities. Further, photodynamic therapy and delivery of proteins/genes can be improved with a deeper research on the employed magnetic material and associated toxicity. A scale-up procedure is also lacking in recent research, which is limiting their translation to clinical use.

Nonspherical Metal-Based Nanoarchitectures: Synthesis and Impact of Size, Shape, and Composition on Their Biological Activity

Metal-based nanoentities, apart from being indispensable research tools, have found extensive use in the industrial and biomedical arena. Because their biological impacts are governed by factors such as size, shape, and composition, such issues must be taken into account when these materials are incorporated into multi-component ensembles for clinical applications. The size and shape (rods, wires, sheets, tubes, and cages) of metallic nanostructures influence cell viability by virtue of their varied geometry and physicochemical interactions with mammalian cell membranes. The anisotropic properties of nonspherical metal-based nanoarchitectures render them exciting candidates for biomedical applications. Here, the size-, shape-, and composition-dependent properties of nonspherical metal-based nanoarchitectures are reviewed in the context of their potential applications in cancer diagnostics and therapeutics, as well as, in regenerative medicine. Strategies for the synthesis of nonspherical metal-based nanoarchitectures and their cytotoxicity and immunological profiles are also comprehensively appraised.

Hybrid magnetic nanoparticles as efficient nanoheaters in biomedical applications

Heating at the nanoscale is the basis of several biomedical applications, including magnetic hyperthermia therapies and heat-triggered drug delivery. The combination of multiple inorganic materials in hybrid magnetic nanoparticles provides versatile platforms to achieve an efficient heat delivery upon different external stimuli or to get an optical feedback during the process. However, the successful design and application of these nanomaterials usually require intricate synthesis routes and their magnetic response is still not fully understood. In this review we give an overview of the novel systems reported in the last few years, which have been mostly obtained by organic phase-based synthesis and epitaxial growth processes. Since the heating efficiency of hybrid magnetic nanoparticles often relies on the exchange-interaction between their components, we discuss various interface-phenomena that are responsible for their magnetic properties. Finally, followed by a brief comment on future directions in the field, we outline recent advances on multifunctional nanoparticles that can boost the heating power with light and combine heating and temperature sensing in a single nanomaterial.

Anti-CEA tagged iron nanoparticles for targeting triple-negative breast cancer

Systemic therapy is generally required for breast cancer. However, treatment toxicity and side effects are a concern, especially for triple-negative breast cancer (TNBC), a subtype that usually develops resistance to chemotherapy. To overcome this issue, new nanoformulations capable of targeting cancer cells have been developed and alternative biomarkers have been explored as target molecules for TNBC management. In this study, we performed an in vivo assay in a murine orthotopic TNBC model to evaluate the targeting ability of anti-carcinoembryonic antigen (anti-CEA) loaded nanoparticles (labelled MFCEA), which had been previously synthetized by our research group. 4T1 cells were injected in the mammary gland of balb-c mice, and tumors were evaluated for CEA expression by immunohistochemistry. Tumor-bearing mice received targeted (MFCEA) and non-targeted (MF) nanoparticles intraperitoneally. Tumors were removed 1, 4, 15 and 24h after treatment, and Prussian blue iron staining was performed. Our results showed, as far as we know for the first time, that 4T1 induced tumors are CEA positive, and this opens up new prospects for treating TNBC. Furthermore, MFCEA nanoparticles were able to target malignant tissue and were retained in the tumor for longer than MF nanoparticles. The retention property of MFCEA, together with the absence of toxicity observed in the MTT assay, make these nanoparticles a promising device for management of CEA positive tumors and perhaps for TNBC. Nevertheless, further studies must be carried out to improve their performance and ensure safety for clinical studies.

Review on the advancements of magnetic gels: towards multifunctional magnetic liposome-hydrogel composites for biomedical applications

Magnetic gels have been gaining great attention in nanomedicine, as they combine features of hydrogels and magnetic nanoparticles into a single system. The incorporation of liposomes in magnetic gels further leads to a more robust multifunctional system enabling more functions and spatiotemporal control required for biomedical applications, which includes on-demand drug release. In this review, magnetic gels components are initially introduced, as well as an overview of advancements on the development, tuneability, manipulation and application of these materials. After a discussion of the advantages of combining hydrogels with liposomes, the properties, fabrication strategies and applications of magnetic liposome-hydrogel composites (magnetic lipogels or magnetolipogels) are reviewed. Overall, the progress of magnetic gels towards smart multifunctional materials are emphasized, considering the contributions for future developments.

Role of Magnetic Anisotropy on the Hyperthermia Efficiency in Spherical Fe3−xCoxO4 (x = 0–1) Nanoparticles

The use of magnetic nanoparticles in the treatment of cancer using alternating current hyperthermia therapy has shown the potential to replace or supplement conventional cancer treatments, radiotherapy and chemotherapy, which have severe side effects. Though the nearly spherical sub-10 nm iron oxide nanoparticles have their approval from the US Food and Drug Administration, their low heating efficiency and removal from the body after hyperthermia treatment raises serious concerns. The majority of magnetic hyperthermia research is working to create nanomaterials with improved heating efficiency and long blood circulation time. Here, we have demonstrated a simple strategy to enhance the heating efficiency of sub-10 nm Fe3O4 nanoparticles through the replacement of Fe+2 ions with Co+2 ions. Magnetic and hyperthermia experiments on the 7 nm Fe3−xCoxO4 (x = 0–1) nanoparticles showed that the blocking temperature, the coercivity at 10 K, and the specific absorption rate followed a similar trend with a maximum at x = 0.75, which is in corroboration with the theoretical prediction. Our study revealed that the heating efficiency of the Fe3−xCoxO4 (x = 0–1) nanoparticles varies not just with the size and saturation magnetization but also with the magnetocrystalline anisotropy of the particles.

In vivo magnetic nanoparticle hyperthermia: a review on preclinical studies, low-field nano-heaters, noninvasive thermometry and computer simulations for treatment planning

Magnetic nanoparticle hyperthermia (MNH) is a promising nanotechnology-based cancer thermal therapy that has been approved for clinical use, together with radiation therapy, for treating brain tumors. Almost ten years after approval, few new clinical applications had appeared, perhaps because it cannot benefit from the gold standard noninvasive MRI thermometry technique, since static magnetic fields inhibit heat generation. This might limit its clinical use, in particular as a single therapeutic modality. In this article, we review the in vivo MNH preclinical studies, discussing results of the last two decades with emphasis on safety as a clinical criteria, the need for low-field nano-heaters and noninvasive thermal dosimetry, and the state of the art of computational modeling for treatment planning using MNH. Limitations to more effective clinical use are discussed, together with suggestions for future directions, such as the development of ultrasound-based, computed tomography-based or magnetic nanoparticle-based thermometry to achieve greater impact on clinical translation of MNH.

Design and application of inorganic nanoparticles for sonodynamic cancer therapy

This review focus on the recent developments in inorganic nanomaterials for tumor SDT.

Shell-mediated control of surface chemistry of highly stoichiometric magnetite nanoparticles

Magnetite (Fe3O4) nanoparticles are one of the most studied nanomaterials for different nanotechnological and biomedical applications. However, Fe3O4 nanomaterials gradually oxidize to maghemite (γ-Fe2O3) under conventional environmental conditions leading to changes in their functional properties that determine their performance in many applications. Here we propose a novel strategy to control the surface chemistry of monodisperse 12 nm magnetite nanoparticles by means of a 3 nm-thick Zn-ferrite epitaxial coating in core/shell nanostructures. We have carried out a combined Mössbauer spectroscopy, dc magnetometry, X-ray photoelectron spectroscopy and spatially resolved electron energy loss spectroscopy study on iron oxide and Fe3O4/Zn0.6Fe2.4O4 core/shell nanoparticles aged under ambient conditions for 6 months. Our results reveal that while the aged iron oxide nanoparticles consist of a mixture of γ-Fe2O3 and Fe3O4, the Zn-ferrite-coating preserves a highly stoichiometric Fe3O4 core. Therefore, the aged core/shell nanoparticles present a sharp Verwey transition, an increased saturation magnetization and the possibility of tuning the effective anisotropy through exchange-coupling at the core/shell interface. The inhibition of the oxidation of the Fe3O4 cores can be accounted for in terms of the chemical nature of the shell layer and an epitaxial crystal symmetry matching between the core and the shell.

Photothermal Depletion of Cancer-Associated Fibroblasts Normalizes Tumor Stiffness in Desmoplastic Cholangiocarcinoma

Physical oncology recognizes tissue stiffness mediated by activation of cancer-associated fibroblasts (CAF) and extracellular matrix remodeling as an active modulator of tumorigenesis, treatment resistance, and clinical outcome. Cholangiocarcinoma (CCA) is a highly aggressive and chemoresistant desmoplastic cancer enriched in CAF. CCA's stroma mechanical properties are considered responsible for its chemoresistant character. To normalize tumor mechanics, we propose a physical strategy based on remotely light-activated nanohyperthermia to modulate the tumor microenvironment. In this study, we report the use of multifunctional iron oxide nanoflowers decorated with gold nanoparticles (GIONF) as efficient nanoheaters to achieve complete tumor regression following three sessions of mild hyperthermia. The preferential uptake of GIONF by CAF allowed targeting this cell population, which resulted in a significant early reduction of tumor stiffness followed by tumor regression. In conclusion, our study highlights a spatially and temporally controlled physical strategy, GIONF-mediated photothermal therapy to deplete CAF and normalize the tumor mechanics that may apply to desmoplastic cancer and CCA treatment.

Multifunctional magnetic iron oxide nanoparticles: an advanced platform for cancer theranostics

Multifunctional magnetic nanoparticles and derivative nanocomposites have aroused great concern for multimode imaging and cancer synergistic therapies in recent years. Among the rest, functional magnetic iron oxide nanoparticles (Fe3O4 NPs) have shown great potential as an advanced platform because of their inherent magnetic resonance imaging (MRI), biocatalytic activity (nanozyme), magnetic hyperthermia treatment (MHT), photo-responsive therapy and drug delivery for chemotherapy and gene therapy. Magnetic Fe3O4 NPs can be synthesized through several methods and easily surface modified with biocompatible materials or active targeting moieties. The MRI capacity could be appropriately modulated to induce response between T1 and T2 modes by controlling the size distribution of Fe3O4 NPs. Besides, small-size nanoparticles are also desired due to the enhanced permeation and retention (EPR) effect, thus the imaging and therapeutic efficiency of Fe3O4 NP-based platforms can be further improved. Here, we firstly retrospect the typical synthesis and surface modification methods of magnetic Fe3O4 NPs. Then, the latest biomedical application including responsive MRI, multimodal imaging, nanozyme, MHT, photo-responsive therapy and drug delivery, the mechanism of corresponding treatments and cooperation therapeutics of multifunctional Fe3O4 NPs are also be explained. Finally, we also outline a brief discussion and perspective on the possibility of further clinical translations of these multifunctional nanomaterials. This review would provide a comprehensive reference for readers to understand the multifunctional Fe3O4 NPs in cancer diagnosis and treatment.

A Guideline for Effectively Synthesizing and Characterizing Magnetic Nanoparticles for Advancing Nanobiotechnology: A Review

The remarkable multimodal functionalities of magnetic nanoparticles, conferred by their size and morphology, are very important in resolving challenges slowing the progression of nanobiotechnology. The rapid and revolutionary expansion of magnetic nanoparticles in nanobiotechnology, especially in nanomedicine and therapeutics, demands an overview of the current state of the art for synthesizing and characterizing magnetic nanoparticles. In this review, we explain the synthesis routes for tailoring the size, morphology, composition, and magnetic properties of the magnetic nanoparticles. The pros and cons of the most popularly used characterization techniques for determining the aforementioned parameters, with particular focus on nanomedicine and biosensing applications, are discussed. Moreover, we provide numerous biomedical applications and highlight their challenges and requirements that must be met using the magnetic nanoparticles to achieve the most effective outcomes. Finally, we conclude this review by providing an insight towards resolving the persisting challenges and the future directions. This review should be an excellent source of information for beginners in this field who are looking for a groundbreaking start but they have been overwhelmed by the volume of literature.

Shape Anisotropic Iron Oxide-Based Magnetic Nanoparticles: Synthesis and Biomedical Applications

Research on iron oxide-based magnetic nanoparticles and their clinical use has been, so far, mainly focused on the spherical shape. However, efforts have been made to develop synthetic routes that produce different anisotropic shapes not only in magnetite nanoparticles, but also in other ferrites, as their magnetic behavior and biological activity can be improved by controlling the shape. Ferrite nanoparticles show several properties that arise from finite-size and surface effects, like high magnetization and superparamagnetism, which make them interesting for use in nanomedicine. Herein, we show recent developments on the synthesis of anisotropic ferrite nanoparticles and the importance of shape-dependent properties for biomedical applications, such as magnetic drug delivery, magnetic hyperthermia and magnetic resonance imaging. A brief discussion on toxicity of iron oxide nanoparticles is also included.

Janus Magnetic-Plasmonic Nanoparticles for Magnetically Guided and Thermally Activated Cancer Therapy

Progress of thermal tumor therapies and their translation into clinical practice are limited by insufficient nanoparticle concentration to release therapeutic heating at the tumor site after systemic administration. Herein, the use of Janus magneto-plasmonic nanoparticles, made of gold nanostars and iron oxide nanospheres, as efficient therapeutic nanoheaters whose on-site delivery can be improved by magnetic targeting, is proposed. Single and combined magneto- and photo-thermal heating properties of Janus nanoparticles render them as compelling heating elements, depending on the nanoparticle dose, magnetic lobe size, and milieu conditions. In cancer cells, a much more effective effect is observed for photothermia compared to magnetic hyperthermia, while combination of the two modalities into a magneto-photothermal treatment results in a synergistic cytotoxic effect in vitro. The high potential of the Janus nanoparticles for magnetic guiding confirms them to be excellent nanostructures for in vivo magnetically enhanced photothermal therapy, leading to efficient tumor growth inhibition.