Rational Design of Branched Au-Fe3 O4 Janus Nanoparticles for Simultaneous Trimodal Imaging and Photothermal Therapy of Cancer Cells

Beta cyclodextrin conjugated AuFe3O4 Janus nanoparticles with enhanced chemo-photothermal therapy performance

The strategic integration of multi-functionalities within a singular nanoplatform has received growing attention for enhancing treatment efficacy, particularly in chemo-photothermal therapy. This study introduces a comprehensive concept of Janus nanoparticles (JNPs) composed of Au and Fe3O4 nanostructures intricately bonded with β-cyclodextrins (β-CD) to encapsulate 5-Fluorouracil (5-FU) and Ibuprofen (IBU). This strategic structure is engineered to exploit the synergistic effects of chemo-photothermal therapy, underscored by their exceptional biocompatibility and photothermal conversion efficiency (∼32.88 %). Furthermore, these β-CD-conjugated JNPs enhance photodynamic therapy by generating singlet oxygen (1O2) species, offering a multi-modality approach to cancer eradication. Computer simulation results were in good agreement with in vitro and in vivo assays. Through these studies, we were able to prove the improved tumor ablation ability of the drug-loaded β-CD-conjugated JNPs, without inducing adverse effects in tumor-bearing nude mice. The findings underscore a formidable tumor ablation potency of β-CD-conjugated Au-Fe3O4 JNPs, heralding a new era in achieving nuanced, highly effective, and side-effect-free cancer treatment modalities. STATEMENT OF SIGNIFICANCE: The emergence of multifunctional nanoparticles marks a pivotal stride in cancer therapy research. This investigation unveils Janus nanoparticles (JNPs) amalgamating gold (Au), iron oxide (Fe3O4), and β-cyclodextrins (β-CD), encapsulating 5-Fluorouracil (5-FU) and Ibuprofen (IBU) for synergistic chemo-photothermal therapy. Demonstrating both biocompatibility and potent photothermal properties (∼32.88 %), these JNPs present a promising avenue for cancer treatment. Noteworthy is their heightened photodynamic efficiency and remarkable tumor ablation capabilities observed in vitro and in vivo, devoid of adverse effects. Furthermore, computational simulations validate their interactions with cancer cells, bolstering their utility as an emerging therapeutic modality. This endeavor pioneers a secure and efficacious strategy for cancer therapy, underscoring the significance of β-CD-conjugated Au-Fe3O4 JNPs as innovative nanoplatforms with profound implications for the advancement of cancer therapy.

Au-Fe3O4 Janus nanoparticles for imaging-guided near infrared-enhanced ferroptosis therapy in triple negative breast cancer

Triple-negative breast cancer (TNBC) is insensitive to conventional therapy due to its highly invasive nature resulting in poor therapeutic outcomes. Recent studies have shown multiple genes associated with ferroptosis in TNBC, suggesting an opportunity for ferroptosis-based treatment of TNBC. However, the efficiency of present ferroptosis agents for cancer is greatly restricted due to lack of specificity and low intracellular levels of H2O2 in cancer cells. Herein, we report a nano-theranostic platform consisting of gold (Au)-iron oxide (Fe3O4) Janus nanoparticles (GION@RGD) that effectively enhances the tumor-specific Fenton reaction through utilization of near-infrared (NIR) lasers, resulting in the generation of substantial quantities of toxic hydroxyl radicals (•OH). Specifically, Au nanoparticles (NPs) converted NIR light energy into thermal energy, inducing generation of abundant intracellular H2O2, thereby enhancing the iron-induced Fenton reaction. The generated •OH not only lead to apoptosis of malignant tumor cells but also induce the accumulation of lipid peroxides, causing ferroptosis of tumor cells. After functionalizing with the activity-targeting ligand RGD (Arg-Gly-Asp), precise synergistic treatment of TNBC was achieved in vivo under the guidance of Fe3O4 enhanced T2-weighted magnetic resonance imaging (MRI). This synergistic treatment strategy of NIR-enhanced ferroptosis holds promise for the treatment of TNBC.

Gold-semiconductor nanohybrids as advanced phototherapeutics

Phototherapeutics is gaining momentum as a mainstream treatment for cancer, with gold-semiconductor nanocomposites showing promise as potent phototherapeutic agents due to their structural tunability, biocompatibility and functional diversity. Such nanohybrids possess plasmonic characteristics in the presence of gold and the catalytic nature of semiconductor units, as well as the unexpected physicochemical properties arising from the contact interface. This perspective provides an overview of the latest research on gold-semiconductor nanocomposites for photodynamic, photothermal and photocatalytic therapy. The relationship between the spatial configuration of these nanohybrids and their practical performance was explored to deliver comprehensive insights and guidance for the design and fabrication of novel composite nanoplatforms to enhance the efficiency of phototherapeutics, promoting the development of nanotechnology-based advanced biomedical applications.

Gold-iron oxide (Au/Fe3O4) magnetic nanoparticles as the nanoplatform for binding of bioactive molecules through self-assembly

Nanomedicine plays a crucial role in the development of next-generation therapies. The use of nanoparticles as drug delivery platforms has become a major area of research in nanotechnology. To be effective, these nanoparticles must interact with desired drug molecules and release them at targeted sites. The design of these “nanoplatforms” typically includes a functional core, an organic coating with functional groups for drug binding, and the drugs or bioactive molecules themselves. However, by exploiting the coordination chemistry between organic molecules and transition metal centers, the self-assembly of drugs onto the nanoplatform surfaces can bypass the need for an organic coating, simplifying the materials synthesis process. In this perspective, we use gold-iron oxide nanoplatforms as examples and outline the prospects and challenges of using self-assembly to prepare drug-nanoparticle constructs. Through a case study on the binding of insulin on Au-dotted Fe3O4 nanoparticles, we demonstrate how a self-assembly system can be developed. This method can also be adapted to other combinations of transition metals, with the potential for scaling up. Furthermore, the self-assembly method can also be considered as a greener alternative to traditional methods, reducing the use of chemicals and solvents. In light of the current climate of environmental awareness, this shift towards sustainability in the pharmaceutical industry would be welcomed.

A Catalytic Immune Activator Based on Magnetic Nanoparticles to Reprogram the Immunoecology of Breast Cancer from "Cold" to "Hot" State

Triple-negative breast cancer (TNBC) as "cold" tumor is characterized by severe immunosuppression of the tumor microenvironment (TME). To effectively activate the immune response of TNBC, a new kind of therapy strategy called cancer catalytic immunotherapy is proposed based on magnetic nanoparticles (NPs) as immune activators. Utilizing the weak acidity and excessive hydrogen peroxide of TME, these magnetic NPs can release ferrous ions to promote Fenton reaction, leading to abundant ·OH and reactive oxygen species (ROS) for ultimately killing cancer cells. Mechanistically, these magnetic NPs activate the ROS-related signaling pathway to generate more ROS. Meanwhile, these magnetic NPs with unique immunological properties can promote the maturation of dendritic cells and the polarization of macrophages from M2 to M1, resulting in the infiltration of more T cells to reprogram the immunoecology of TNBC from "cold" to "hot" state. Besides directly affecting immune cells, these magnetic NPs can also affect the secretion of some immune-related cytokines by cancer cells, to further indirectly activate the immune response. In conclusion, these catalytic immune activators are designed to achieve the synergistic treatment of chemodynamic therapy-enhanced immunotherapy guided by computed tomography (CT)/near-infrared region-II (NIR-II) dual-mode imaging, providing a new strategy for TNBC treatment.

Recent progress on bioimaging strategies based on Janus nanoparticles

Janus nanoparticles refer to a kind of asymmetric-structured nanoparticles composed of two or more distinct sides with differences in chemical nature and/or polarity on each side and thus can integrate two or more properties in one single particle. Due to their unique structure and surface properties, Janus nanoparticles have shown broad application potentials in optics, nuclear magnetic resonance, multi-mode imaging, and other fields. Unlike traditional contrast agents used in biological imaging, Janus nanoparticles are asymmetrically and directionally oriented to ensure stable partitioning of individual nanoparticles while integrating more functions. Much advancement have been carried out in the past few years, with some studies partially covering bioimaging applications. However, to our best knowledge, there are still no review papers specifically dedicated to the bioimaging applications with Janus nanoparticles. Bearing this in mind and taking the current challenges in this field into consideration, herein, we discuss representative approaches orchestrated for bioimaging applications, with the focus on the improvement of imaging quality brought by Janus nanoparticles and the development of multifunctional nanoplatforms in biological imaging fields, such as theranostics and therapies. Finally, based on the research experience of our group in this field, prospects for future research trends are put forward to provide new ideas for designing new Janus nanoparticles for clinical bioimaging.

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.

Janus bifunctional periodic mesoporous organosilica

Synthesis of a Janus periodic mesoporous organosilica material (JPMO) is presented here. In this strategy, the surface of the hollow silica material was selectively functionalized with two different bridged organic-inorganic hybrid groups. It was found that the resulting bifunctional material is able to form a stable Pickering emulsion. This new type of PMO material may be suitable for widespread applications in various fields related to material science and catalysis.

The role of morphology, shell composition and protein corona formation in Au/Fe3O4 composite nanoparticle mediated macrophage responses

The great interest in using nanoparticles (NPs) for biomedical applications is transversal to various materials despite the poorly understood correlation between their physicochemical properties and effects on the immune system. NPs, such as gold and Fe₃O₄, are generally regarded as safe, but the immunotoxicological profile of Au/Fe₃O₄ composite NPs with different physicochemical properties is not well documented. This study investigated the biological impact of Au/Fe₃O₄ composite NPs with different morphologies (spherical core-shell and flower-like) and shell composition in vitro to analyze their potential cytotoxic effects and inflammatory responses on RAW 264.7 cells. Au/Fe₃O₄ composite NPs with a flower-like structure (FLNPs) induce a pronounced reduction in cell viability compared with Au/Fe₃O₄ composite NPs with a spherical core-shell structure (CSNPs). The increased production of reactive oxygen species, which damages cellular membranes, might contribute to the cytotoxicity effect of FLNPs. However, CSNPs presented more RAW 264.7 cell adhesion and uptake than FLNPs. Remarkably, a significant TNF-α release was observed with CSNP treated RAW 264.7 cells other than that of FLNPs. Protein corona analysis revealed the adsorption of a distinct amount and profile of proteins on the surface of CSNPs and FLNPs. Given the similar particle size and ζ-potential of CSNPs and FLNPs under the cell culture condition, results indicate that the impact of Au/Fe₃O₄ composite NPs on the macrophage activity highly depends on their morphology, shell composition and protein corona profile.

Magnetic Nanoparticle Composites: Synergistic Effects and Applications

Composite materials are made from two or more constituent materials with distinct physical or chemical properties that, when combined, produce a material with characteristics which are at least to some degree different from its individual components. Nanocomposite materials are composed of different materials of which at least one has nanoscale dimensions. Common types of nanocomposites consist of a combination of two different elements, with a nanoparticle that is linked to, or surrounded by, another organic or inorganic material, for example in a core-shell or heterostructure configuration. A general family of nanoparticle composites concerns the coating of a nanoscale material by a polymer, SiO2 or carbon. Other materials, such as graphene or graphene oxide (GO), are used as supports forming composites when nanoscale materials are deposited onto them. In this Review we focus on magnetic nanocomposites, describing their synthetic methods, physical properties and applications. Several types of nanocomposites are presented, according to their composition, morphology or surface functionalization. Their applications are largely due to the synergistic effects that appear thanks to the co-existence of two different materials and to their interface, resulting in properties often better than those of their single-phase components. Applications discussed concern magnetically separable catalysts, water treatment, diagnostics-sensing and biomedicine.

Engineered Fe3O4-based nanomaterials for diagnosis and therapy of cancer

Recent developments of Fe₃O₄ NP-based theranostic nanoplatforms and their applications in tumor-targeted imaging and therapy.

Improved Stability and Photothermal Performance of Polydopamine-Modified Fe3 O4 Nanocomposites for Highly Efficient Magnetic Resonance Imaging-Guided Photothermal Therapy

Magnetic nanomaterials are a promising class of contrast agents for magnetic resonance imaging (MRI). However, their poor stability and low relaxivity are major challenges hindering their clinical applications. In this study, magnetic theranostic nanoagents based on polydopamine-modified Fe₃ O₄ (Fe₃ O₄ @PDA) nanocomposites are fabricated for MRI-guided photothermal therapy (PTT) cancer treatments. Their high transverse relaxivity of 337.8 mM^-1 s^-1 makes these Fe₃ O₄ @PDA nanocomposites a promising T₂ -weighted MRI contrast agent for cancer diagnosis and image-guided cancer therapy. Due to the good photothermal effect of polydopamine (PDA), the tumors of 4T1 tumor-bearing mice are completely excised by PTT. Most importantly, the PDA shell also improves the stability of the Fe₃ O₄ @PDA nanocomposites, which contributes to their excellent, long-term performance in MRI and PTT applications. Their good stability, high T₂ relaxivity, robust biocompatibility, and satisfactory treatment effect give these Fe₃ O₄ @PDA nanocomposites great potential for use in cancer theranostics.

Janus Nanoparticles with Tunable Amphiphilicity for Stabilizing Pickering-Emulsion Droplets via Assembly Behavior at Oil-Water Interfaces

Janus particles (JNPs) with controlled anisotropies are regarded as promising materials for sophisticated building blocks and assembly. Herein a straightforward method was proposed for the synthesis of uniformly distributed JNPs with controllable anisotropies, showing two compartmental bulbs with different surface wettability. The synthetic strategy is based on the phase separation-induced styrene liquid protrusion on seed poly(styrene-co-acrylic acid) (CPSAA) nanoparticles via controlled swelling, with the formed polystyrene (PS) and CPSAA compartments corresponding to the amount of monomers. The size (lateral length) ratio of formed PS and CPSAA bulbs, D_PS/D_CPSAA, defined as "Janusity", has been precisely tuned in the range of 0-0.91 by controlling the mass ratio of two monomers. Obtained JNPs with tunable amphiphilicity are utilized as colloid surfactants to prepare Pickering-emulsions of both water-in-oil (W/O) and oil-in-water (O/W) with proper Janusity. The stability of achieved W/O and O/W Pickering-emulsions is dependent on the adhesion energy of a JNP at the water-oil interfaces. Prepared JNPs have also being utilized to prepare and stabilize monodisperse droplets in microfluidic devices, demonstrating their high potential for fundamental research and practical applications.

Chemical Synthesis of Magnetic Nanoparticles for Permanent Magnet Applications

Permanent magnets are a class of critical materials for information storage, energy storage, and other magneto-electronic applications. Compared with conventional bulk magnets, magnetic nanoparticles (MNPs) show unique size-dependent magnetic properties, which make it possible to control and optimize their magnetic performance for specific applications. The synthesis of MNPs has been intensively explored in recent years. Among different methods developed thus far, chemical synthesis based on solution-phase reactions has attracted much attention owing to its potential to achieve the desired size, morphology, structure, and magnetic controls. This Minireview focuses on the recent chemical syntheses of strongly ferromagnetic MNPs (H_c >10 kOe) of rare-earth metals and FePt intermetallic alloys. It further discusses the potential of enhancing the magnetic performance of MNP composites by assembly of hard and soft MNPs into exchange-coupled nanocomposites. High-performance nanocomposites are key to fabricating super-strong permanent magnets for magnetic, electronic, and energy applications.

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.

Reverse Microemulsion Synthesis of Fe3O4-Ag2S Heteronanocrystals for Dual-Modal Imaging-Guided Photothermal Tumor Ablation

Heterojunction nanomaterials have revealed a significant possibility in tumor diagnosis and therapeutic owing to tightly combining two parts of different chemical properties. Herein, we successfully synthesized heterogenous Fe₃O₄-Ag₂S nanocrystals through a reverse microemulsion. Based on the prepared heterostructure, a new drug nanoplatform was developed, which served as a contrast agent for T₂-weighted magnetic resonance imaging, computed tomography imaging, and photothermal imaging. In addition, these Fe₃O₄-Ag₂S heteronanocrystals exhibited a high photothermal conversion efficiency of 75.5% irradiated by a laser of 808 nm wavelength. After injection into glioma cancer mode in vivo, efficient tumor accumulation of Fe₃O₄-Ag₂S heteronanocrystals was observed under triple-modal imaging. The prepared heteronanocrystals further showed an excellent ablated tumor destruction effect through the generated hyperthermia with the irradiation of an 808 nm laser. Our work suggests that the potential of Fe₃O₄-Ag₂S heteronanocrystals may be a promising theranostic agent for multimodal imaging guidance and photothermal therapy toward cancer.

Janus particles: recent advances in the biomedical applications

Janus particles, which are named after the two-faced Roman god Janus, have two distinct sides with different surface features, structures, and compositions. This asymmetric structure enables the combination of different or even incompatible physical, chemical, and mechanical properties within a single particle. Much effort has been focused on the preparation of Janus particles with high homogeneity, tunable size and shape, combined functionalities, and scalability. With their unique features, Janus particles have attracted attention in a wide range of applications such as in optics, catalysis, and biomedicine. As a biomedical device, Janus particles offer opportunities to incorporate therapeutics, imaging, or sensing modalities in independent compartments of a single particle in a spatially controlled manner. This may result in synergistic actions of combined therapies and multi-level targeting not possible in isotropic systems. In this review, we summarize the latest advances in employing Janus particles as therapeutic delivery carriers, in vivo imaging probes, and biosensors. Challenges and future opportunities for these particles will also be discussed.

Janus nanoparticles in cancer diagnosis, therapy and theranostics

Anisotropic Janus nanoparticles (JNPs), due to their several distinct merits, have been widely investigated for cancer theranostics.

AgBiS2-TPP nanocomposite for mitochondrial targeting photodynamic therapy, photothermal therapy and bio-imaging under 808 nm NIR laser irradiation

AgBiS₂ nanodots as an NIR light-excited photosensitizer produce a PDT effect, which is reported for the first time.

Preparation of a one-dimensional nanorod/metal organic framework Janus nanoplatform via side-specific growth for synergistic cancer therapy

A unique LA-AuNR/ZIF-8 Janus nanoparticle is firstly prepared by side-specific growth of ZIF-8 on one-dimensional AuNR for drug loading to realize the CT image-guided active targeted synergistic chemo-photothermal cancer therapy.

Biosafety evaluation of Janus Fe3O4-TiO2 nanoparticles in Sprague Dawley rats after intravenous injection

Introduction

Newly synthesized Janus-structured Fe₃O₄-TiO₂ nanoparticles (NPs) appear to be a promising candidate for the diagnosis and therapy of cancer. Although the toxicity of individual Fe₃O₄ or TiO₂ NPs has been studied extensively, the toxicity of Janus Fe₃O₄-TiO₂ NPs is not clear.

Methods

In this study, the biosafety of both Janus Fe₃O₄-TiO₂ NPs (20–25 nm) and the maternal material TiO₂ NPs (7–10 nm) were evaluated in Sprague Dawley rats after one intravenous injection into the tail vein. Healthy rats were randomly divided into one control group and six experimental groups. Thirty days after treatment, rats were killed, then blood and tissue samples were collected for hematological, biochemical, element-content, histopathological, and Western blot analysis.

Results

The results show that only a slight Ti element accumulation in the heart, spleen, and liver could be found in the Janus Fe₃O₄-TiO₂ NP groups (P>0.05 compared with control). However, significant Ti element accumulation in the spleen, lungs, and liver was found in the TiO₂ NP-treated rats. Both Fe₃O₄-TiO₂ NPs and TiO₂ NPs could induce certain histopathological abnormalities. Western blot analysis showed that both NPs could induce certain apoptotic or inflammatory-related molecular protein upregulation in rat livers. A certain degree of alterations in liver function and electrolyte and lipid parameters was also observed in rats treated with both materials. However, compared to Janus structure Fe₃O₄-TiO₂ NP-treated groups, TiO₂ NPs at 30 mg/kg showed more severe adverse effects.

Conclusion

Our results showed that under a low dose (5 mg/kg), both NP types had no significant toxicity in rats. Janus NPs certainly seem less toxic than TiO₂ NPs in rats at 30 mg/kg. To ensure safe use of these newly developed Janus NPs in cancer diagnosis and therapy, further animal studies are needed to evaluate long-term bioeffects.

In vitro evaluation of the toxicity and underlying molecular mechanisms of Janus Fe3 O4 -TiO2 nanoparticles in human liver cells

Recent studies show that Janus Fe3 O4 -TiO2 nanoparticles (NPs) have potential applications as a multifunctional agent of magnetic resonance imaging (MRI) and photodynamic therapy (PDT) for the diagnosis and therapy of cancer. However, little work has been done on their biological effects. To evaluate the toxicity and underlying molecular mechanisms of Janus Fe3 O4 -TiO2 nanoparticles, an in vitro study using a human liver cell line HL-7702 cells was conducted. For comparison, the Janus Fe3 O4 -TiO2 NPs parent material TiO2 NPs was also evaluated. Results showed that both Fe3 O4 -TiO2 NPs and TiO2 NPs decreased cell viability and ATP levels when applied in treatment, but increased malonaldehyde (MDA) and reactive oxygen species (ROS) generation. Mitochondria JC-1 staining assay showed that mitochondrial membrane permeability injury occurred in both NPs treated cells. Cell viability analysis showed that TiO2 NPs induced slightly higher cytotoxicity than Fe3 O4 -TiO2 NPs in HL7702 cells. Western blotting indicated that both TiO2 NPs and Fe3 O4 -TiO2 NPs could induce apoptosis, inflammation, and carcinogenesis related signal protein alterations. Comparatively, Fe3 O4 -TiO2 NPs induced higher signal protein expressions than TiO2 NPs under a high treatment dose. However, under a low dose (6.25 μg/cm2 ), neither NPs had any significant toxicity on HL7702 cells. In addition, our results suggest both Fe3 O4 -TiO2 NPs and TiO2 NPs could induce oxidative stress and have a potential carcinogenetic effect in vitro. Further studies are needed to elaborate the detailed mechanisms of toxicity induced by a high dose of Fe3 O4 -TiO2 NPs.