Tuning the Distance of Rattle-Shaped IONP@Shell-in-Shell Nanoparticles for Magnetically-Targeted Photothermal Therapy in the Second Near-Infrared Window

Functionalized manganese iron oxide nanoparticles: a dual potential magneto-chemotherapeutic cargo in a 3D breast cancer model

Localized heat generation from manganese iron oxide nanoparticles (MIONPs) conjugated with chemotherapeutics under the exposure of an alternating magnetic field (magneto-chemotherapy) can revolutionize targeted breast cancer therapy. On the other hand, the lack of precise control of local temperature and adequate MIONP distribution in laboratory settings using the conventional two-dimensional (2D) cellular models has limited its further translation in tumor sites. Our current study explored advanced 3D in vitro tumor models as a promising alternative to replicate the complete range of tumor characteristics. Specifically, we have focused on investigating the effectiveness of MIONP-based magneto-chemotherapy (MCT) as an anticancer treatment in a 3D breast cancer model. To achieve this, chitosan-coated MIONPs (CS-MIONPs) are synthesized and functionalized with an anticancer drug (doxorubicin) and a tumor-targeting aptamer (AS1411). CS-MIONPs with a crystallite size of 16.88 nm and a specific absorption rate (SAR) of 181.48 W g-1 are reported. In vitro assessment of MCF-7 breast cancer cell lines in 2D and 3D cell cultures demonstrated anticancer activity. In the 2D and 3D cancer models, the MIONP-mediated MCT reduced cancer cell viability to about 71.48% and 92.2%, respectively. On the other hand, MIONP-mediated MCT under an AC magnetic field diminished spheroids' viability to 83.76 ± 2%, being the most promising therapeutic modality against breast cancer.

DNA-Templated Ag@Pd Nanoclusters for NIR-II Photoacoustic Imaging-Guided Photothermal-Augmented Nanocatalytic Therapy

Developing multifunctional nanozymes with photothermal-augmented enzyme-like reaction dynamics in the second near-infrared (NIR-II) biowindow is of significance for nanocatalytic therapy (NCT). Herein, DNA-templated Ag@Pd alloy nanoclusters (DNA-Ag@Pd NCs) are prepared as a kind of novel noble-metal alloy nanozymes by using cytosine-rich hairpin-shaped DNA structures as growth templates. DNA-Ag@Pd NCs exhibit high photothermal conversion efficiency (59.32%) under 1270 nm laser and photothermally augmented peroxidase-mimicking activity with synergetic enhancement between Ag and Pd. In addition, hairpin-shaped DNA structures on the surface of DNA-Ag@Pd NCs endow them with good stability and biocompatibility in vitro and in vivo, and enhanced permeability and retention effect at tumor sites. Upon intravenous injection, DNA-Ag@Pd NCs demonstrate high-contrast NIR-II photoacoustic imaging-guided efficient photothermal-augmented NCT of gastric cancer. This work provides a strategy to synthesize versatile noble-metal alloy nanozymes in a bioinspired way for highly efficient therapy of tumors.

A Spiky Silver-Iron Oxide Nanoparticle for Highly Efficient Targeted Photothermal Therapy and Multimodal Imaging of Thrombosis

Thrombosis and its complications are responsible for 30% of annual deaths. Limitations of methods for diagnosing and treating thrombosis highlight the need for improvements. Agents that provide simultaneous diagnostic and therapeutic activities (theranostics) are paramount for an accurate diagnosis and rapid treatment. In this study, silver-iron oxide nanoparticles (AgIONPs) are developed for highly efficient targeted photothermal therapy and imaging of thrombosis. Small iron oxide nanoparticles are employed as seeding agents for the generation of a new class of spiky silver nanoparticles with strong absorbance in the near-infrared range. The AgIONPs are biofunctionalized with binding ligands for targeting thrombi. Photoacoustic and fluorescence imaging demonstrate the highly specific binding of AgIONPs to the thrombus when functionalized with a single chain antibody targeting activated platelets. Photothermal thrombolysis in vivo shows an increase in the temperature of thrombi and a full restoration of blood flow for targeted group but not in the non-targeted group. Thrombolysis from targeted groups is significantly improved (p < 0.0001) in comparison to the standard thrombolytic used in the clinic. Assays show no apparent side effects of AgIONPs. Altogether, this work suggests that AgIONPs are potential theranostic agents for thrombosis.

Hepatotoxic and Neurotoxic Potential of Iron Oxide Nanoparticles in Wistar Rats: a Biochemical and Ultrastructural Study

Iron oxide nanoparticles (IONPs) are increasingly being employed for in vivo biomedical nanotheranostic applications. The development of novel IONPs should be accompanied by careful scrutiny of their biocompatibility. Herein, we studied the effect of administration of three formulations of IONPs, based on their starting materials along with synthesizing methods, IONPs-chloride, IONPs-lactate, and IONPs-nitrate, on biochemical and ultrastructural aspects. Different techniques were utilized to assess the effect of different starting materials on the physical, morphological, chemical, surface area, magnetic, and particle size distribution accompanied with their surface charge properties. Their nanoscale sizes were below 40 nm and demonstrated surface up to 69m²/g, and increased magnetization of 71.273 emu/g. Moreover, we investigated the effects of an oral IONP administration (100 mg/kg/day) in rat for 14 days. The liver enzymatic functions were investigated. Liver and brain tissues were analyzed for oxidative stress. Finally, a transmission electron microscope (TEM) and inductively coupled plasma optical emission spectrometer (ICP-OES) were employed to investigate the ultrastructural alterations and to estimate content of iron in the selected tissues of IONP-exposed rats. This study showed that magnetite IONPs-chloride exhibited the safest toxicological profile and thus could be regarded as a promising nanotherapeutic candidate for brain or liver disorders.

Ultrathin Two-Dimensional Plasmonic PtAg Nanosheets for Broadband Phototheranostics in Both NIR-I and NIR-II Biowindows

Broadband near-infrared (NIR) photothermal and photoacoustic agents covering from the first NIR (NIR-I) to the second NIR (NIR-II) biowindow are of great significance for imaging and therapy of cancers. In this work, ultrathin two-dimensional plasmonic PtAg nanosheets are discovered with strong broadband light absorption from NIR-I to NIR-II biowindow, which exhibit outstanding photothermal and photoacoustic effects under both 785 and 1064 nm lasers. Photothermal conversion efficiencies (PCEs) of PtAg nanosheets reach 19.2% under 785 nm laser and 45.7% under 1064 nm laser. The PCE under 1064 nm laser is higher than those of most reported inorganic NIR-II photothermal nanoagents. After functionalization with folic acid modified thiol-poly(ethylene glycol) (SH-PEG-FA), PtAg nanosheets endowed with good biocompatibility and 4T1 tumor-targeted function give high performances for photoacoustic imaging (PAI) and photothermal therapy (PTT) in vivo under both 785 and 1064 nm lasers. The effective ablation of tumors in mice can be realized without side effects and tumor metastasis by PAI-guided PTT of PtAg nanosheets under 785 or 1064 nm laser. The results demonstrate that the prepared PtAg nanosheets with ultrathin thickness and small size can serve as a promising phototheranostic nanoplatform for PAI-guided PTT of tumors in both NIR-I and NIR-II biowindows.

Rational design of tandem catalysts using a core-shell structure approach

A facile and rational approach to synthesize bimetallic heterogeneous tandem catalysts is presented. Using core-shell structures, it is possible to create spatially controlled ensembles of different nanoparticles and investigate coupled chemocatalytic reactions. The CO2 hydrogenation to methane and light olefins was tested, achieving a tandem process successfully.

Recent advances in iron oxide nanoparticles for brain cancer theranostics: from in vitro to clinical applications

Introduction: Today, the development of multifunctional nanoplatforms is more seriously considered in the field of cancer theranostics.Areas covered: In this respect, nanoparticles provide several advantages over the routine, conventional diagnostic methods, and treatments. Due to the expedient properties of iron oxide nanoparticles, such as being readily modified, great payload potential, intrinsic magnetic qualification, considerable biocompatibility, and overwhelming response to targeting strategies, these nanoparticles can be considered good candidates for application as diagnostic contrast agents and drug/gene delivery vehicles, while also being incorporated into hyperthermia-based approaches. Interestingly, these agents are detectable with routine imaging modalities such as magnetic resonance imaging.Expert opinion: Therefore, combining the traditional diagnostics and therapies with nanotechnological approaches may leave a positive impact on the survival rate of patients with cancer. This review summarizes the application of magnetic iron oxide nanoparticles in both in vitro and in vivo models of brain tumors.

Functionalized nanoprobes for in situ detection of telomerase

Telomerase, a special ribonucleoprotein reverse transcriptase, can maintain the length and stability of telomeres and plays an important role in cell proliferation and differentiation. Due to the distinguishable expression level in normal cells and cancer cells, telomerase has become an important biomarker for cancer diagnosis and prognosis evaluation. Despite major breakthroughs in the field of telomerase detection, the extracts in the cell lysate are still the first choice as the analyte nevertheless, which will bring serious inaccuracies compared with the real intracellular activity. With the development of nanotechnology and nanomaterials, extraordinary progress has been made in telomerase detection by employing different versatile nanoprobes. In this review, we list the superiority of nanoprobes and systematically summarize the applications of nanoprobes in telomerase detection from the aspects of various nanomaterials and discuss the current challenges and potential trends in the future design of nanoprobes.

Amphiphilic Janus nanoparticles for imaging-guided synergistic chemo-photothermal hepatocellular carcinoma therapy in the second near-infrared window

Hepatocellular carcinoma (HCC) is one of the most common and deadly malignant tumors worldwide. With unsatisfactory effects of traditional systematic chemotherapy for HCC owing to its drug resistance, novel therapeutic strategies based on nanomaterials for HCC treatments are promising solutions. To solve the challenges of nanoparticles (NPs)-based drug delivery systems for potential clinical applications, we designed water soluble amphiphilic oleic acid-NaYF4:Yb,Er/polydopamine Au nanoflower Janus NPs (OA-UCNPs/PDA-AuF JNPs) with discrete multi compartment nanostructures as dual-drug delivery systems (DDDSs). This unique nanostructure meets the requirements for containing hydrophobic hydroxycamptothecin/hydrophilic doxorubicin in divided spaces and releasing each drug from non-interfering channels under pH/near-infrared (NIR) dual-stimuli. The amphiphilic DDDSs were utilized to eradicate the tumor burden on a high-fidelity HCC model of a patient-derived xenograft (PDX), and represented an efficient strategy for defeating HCC using multi-modal imaging-guided dual-drug chemo-photothermal therapy in the second NIR window. In addition, the potential mechanisms of action for the DDDSs were evaluated.

MRI-traceable theranostic nanoparticles for targeted cancer treatment

Current cancer therapies, including chemotherapy and radiotherapy, are imprecise, non-specific, and are often administered at high dosages - resulting in side effects that severely impact the patient's overall well-being. A variety of multifunctional, cancer-targeted nanotheranostic systems that integrate therapy, imaging, and tumor targeting functionalities in a single platform have been developed to overcome the shortcomings of traditional drugs. Among the imaging modalities used, magnetic resonance imaging (MRI) provides high resolution imaging of structures deep within the body and, in combination with other imaging modalities, provides complementary diagnostic information for more accurate identification of tumor characteristics and precise guidance of anti-cancer therapy. This review article presents a comprehensive assessment of nanotheranostic systems that combine MRI-based imaging (T1 MRI, T2 MRI, and multimodal imaging) with therapy (chemo-, thermal-, gene- and combination therapy), connecting a range of topics including hybrid treatment options (e.g. combined chemo-gene therapy), unique MRI-based imaging (e.g. combined T1-T2 imaging, triple and quadruple multimodal imaging), novel targeting strategies (e.g. dual magnetic-active targeting and nanoparticles carrying multiple ligands), and tumor microenvironment-responsive drug release (e.g. redox and pH-responsive nanomaterials). With a special focus on systems that have been tested in vivo, this review is an essential summary of the most advanced developments in this rapidly evolving field.

Near-infrared light II - assisted rapid biofilm elimination platform for bone implants at mild temperature

Light-triggered therapy is a prospective method to combat implant-associated infection but near-infrared I (NIR-I) light has insufficient penetrating ability in tissues and local hyperthermia induced by the photothermal treatment may destroy surrounding healthy tissues. Herein, a near-infrared II (NIR-II) phototherapy system composed of upconversion elements doped titanium dioxide nanorods (TiO₂ NRs)/curcumin (Cur)/hyaluronic acid (HA)/bone morphogenetic protein-2 (BMP-2) is designed for biomedical titanium and demonstrated to overcome the above hurdles simultaneously. Incorporation of F, Yb, and Ho not only improves the photocatalytic ability, but also renders the implants with the upconversion capability, so that the NRs can generate enough reactive oxygen species (ROS) when irradiated by the NIR-II laser. Furthermore, the combined actions of quorum sensing inhibitors, ROS, and physical puncture by NRs eliminate Staphylococcus aureus biofilms on titanium rapidly at a mild temperature of 45 °C by only requiring irradiation with the 1060 nm laser for only 15 min in vitro and in vivo. The presence of Cur mitigates the immune response and BMP-2 improves osteogenic differentiation, thus accelerating new bone formation. This low-temperature NIR-II light-triggered antibacterial platform has large potential in combating deep-tissue infection in clinical applications.

Multi-Stimuli-Responsive DOX Released from Magnetosome for Tumor Synergistic Theranostics

Background

To improve responses to tumor microenvironments for achieving a better therapeutic outcome in combination cancer therapy, poly(ε-caprolactone)-SS-poly(methacrylic acid) diblock copolymer (PCL-SS-PMAA) with a disulfide linkage between the hydrophobic and hydrophilic junctions was synthesized.

Materials and Methods

Repeating units of PCL and PMAA in PCL-SS-PMAA were controlled and formulated into polymersomes (PSPps). Truncated octahedral Fe₃O₄ nanoparticles (IONPs) were synthesized and encapsulated to produce IONPs-PSPps NPs and doxorubicin (DOX) was further loaded to produce IONPs-PSPps@DOX NPs for theranostic applications.

Results

IONPs-PSPps NPs remained a superparamagnetic property with a saturation magnetization value of 85 emu⋅g_Fe3O4 ^-1 and a relaxivity value of 180 mM^-1⋅s^-1. Upon exposure to an alternating magnetic field (AMF), IONPs-PSPps NPs increased temperature from 25°C to 54°C within 15 min. Among test groups, the cell apoptosis was greatest in the group exposed to IONPs-PSPps@DOX NPs with AMF and magnet assistance. In vivo T₂-weighted magnetic resonance images of A549 tumor-bearing mice also showed highest contrast and greatest tumor suppression in the tumor with AMF and magnet assistance.

Conclusion

IONPs-PSPps@DOX NPs are a potential theranostic agent having multifaceted applications involving magnetic targeting, MRI diagnosis, hyperthermia and chemotherapy.

Near-infrared-II activated inorganic photothermal nanomedicines

The emergence of near-infrared-II (NIR-II) activated photomedicines has extended the penetration depth for noninvasive theranostics, especially for photothermal nanomedicines. The current early development stage for NIR-II activated photomedicines has focused on creating a greater variety of photothermal agents (PTAs) with superior photothermal conversion ability. However, there is no thorough review for NIR-II inorganic PTAs and most comparisons of the photothermal performances of NIR-II inorganic PTAs are made with NIR-I PTAs. This review will first discuss about the key mechanisms of NIR-II absorption and photothermal conversion. Subsequently, this review will summarize recently developed advanced NIR-II inorganic PTAs based on the dominant inorganic elements and provide a comparison of their NIR-II photothermal performances. The nanostructure design, enhancement strategies and potential biomedical applications will be listed and discussed. We hope this review will further inspire active development and study of NIR-II activated inorganic PTAs with good photothermal conversion ability, multifunctionality, biocompatibility or biodegradability, and disease targeting ability.

Antimicrobial Metal Nanomaterials: From Passive to Stimuli-Activated Applications

The development of antimicrobial drug resistance among pathogenic bacteria and fungi is one of the most significant health issues of the 21st century. Recently, advances in nanotechnology have led to the development of nanomaterials, particularly metals that exhibit antimicrobial properties. These metal nanomaterials have emerged as promising alternatives to traditional antimicrobial therapies. In this review, a broad overview of metal nanomaterials, their synthesis, properties, and interactions with pathogenic micro-organisms is first provided. Secondly, the range of nanomaterials that demonstrate passive antimicrobial properties are outlined and in-depth analysis and comparison of stimuli-responsive antimicrobial nanomaterials are provided, which represent the next generation of microbiocidal nanomaterials. The stimulus applied to activate such nanomaterials includes light (including photocatalytic and photothermal) and magnetic fields, which can induce magnetic hyperthermia and kinetically driven magnetic activation. Broadly, this review aims to summarize the currently available research and provide future scope for the development of metal nanomaterial-based antimicrobial technologies, particularly those that can be activated through externally applied stimuli.

Magnetic iron oxide nanoparticles for imaging, targeting and treatment of primary and metastatic tumors of the brain

Magnetic nanoparticles in general, and iron oxide nanoparticles in particular, have been studied extensively during the past 20 years for numerous biomedical applications. The main applications of these nanoparticles are in magnetic resonance imaging (MRI), magnetic targeting, gene and drug delivery, magnetic hyperthermia for tumor treatment, and manipulation of the immune system by macrophage polarization for cancer treatment. Recently, considerable attention has been paid to magnetic particle imaging (MPI) because of its better sensitivity compared to MRI. In recent years, MRI and MPI have been combined as a dual or multimodal imaging method to enhance the signal in the brain for the early detection and treatment of brain pathologies. Because magnetic and iron oxide nanoparticles are so diverse and can be used in multiple applications such as imaging or therapy, they have attractive features for brain delivery. However, the greatest limitations for the use of MRI/MPI for imaging and treatment are in brain delivery, with one of these limitations being the brain-blood barrier (BBB). This review addresses the current status, chemical compositions, advantages and disadvantages, toxicity and most importantly the future directions for the delivery of iron oxide based substances across the blood-brain barrier for targeting, imaging and therapy of primary and metastatic tumors of the brain.

Synthesis of Gold Nanoparticle: Peptide-Drug Conjugates for Targeted Drug Delivery

Peptide-drug conjugates (PDCs) are being developed for the targeted delivery of drugs to cancer cells. Several approaches are being followed to enhance their stability in biological solutions. Here we describe an effective method to easily couple PDCs to polyethylene-coated gold nanoparticles. We also outline analytical methods to validate the coupling and assays to measure the stability and cytotoxic efficacy of the conjugates.

Bio-application of Inorganic Nanomaterials in Tissue Engineering

Inorganic nanomaterials or nanoparticles (INPs) have drawn high attention for their usage in the biomedical field. In addition to the facile synthetic and modifiable property of INPs, INPs have various unique properties that originate from the components of the INPs, such as metal ions that are essential for the human body. Apart from their roles as components of the human body, inorganic materials have unique properties, such as magnetic, antibacterial, and piezoelectric, so that INPs have been widely used as either carriers or inducers. However, most of the bio-applicable INPs, especially those consisting of metal, can cause cytotoxicity. Therefore, INPs require modification to alleviate the harmful effect toward the cells by controlling the release of metal ions from INPs. Even though many attempts have been made to modify INPs, many things, including the side effects of INPs, still remain as obstacles in the bio-application, which need to be elucidated. In this chapter, we introduce novel INPs in terms of their synthetic method and bio-application in tissue engineering.

Endogenous oxygen generating multifunctional theranostic nanoplatform for enhanced photodynamic-photothermal therapy and multimodal imaging

Phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT), has been considered as a noninvasive option for cancer therapy. However, insufficient penetration depth, tumor hypoxia, and a single treatment method severely limit the effectiveness of treatment. Methods: In this study, a multifunctional theranostic nanoplatform has been fabricated based on Au/Ag-MnO2 hollow nanospheres (AAM HNSs). The Au/Ag alloy HNSs were first synthesized by galvanic replacement reaction and then the MnO2 nanoparticles were deposited on the Au/Ag alloy HNSs by the reaction between Ag and permanganate (KMnO4), finally obtained the AAM HNSs. Then, SH-PEG was modified on the surface of AAM HNSs by the interaction of sulfhydryl and Au/Ag alloy, which improved the dispersibility and biocompatibility of the HNS. Next, the PDT photosensitizer Ce6 was loaded into AAM HNSs, benefiting from the hollow interior of the structure, and the AAM-Ce6 HNSs were obtained. Results: The AAM HNSs exhibit broad absorption at the near infrared (NIR) biological window and remarkable photothermal conversion ability in the NIR-II window. The MnO2 nanoparticles can catalyze endogenous H2O2 to generate O2 and enhance the therapeutic effect of PDT on tumor tissue. Simultaneously, MnO2 nanoparticles intelligently respond to the tumor microenvironment and degrade to release massive Mn2+ ions, which introduce magnetic resonance imaging (MRI) properties. When AAM-Ce6 HNSs are loaded with Ce6, the AAM-Ce6 HNSs can be used for triple-modal imaging (fluorescence/photoacoustic/magnetic resonance imaging, FL/PAI/MRI) guided combination tumor phototherapy (PTT/PDT). Conclusion: This multifunctional nanoplatform shows synergistic therapeutic efficacy better than any single therapy by achieving multimodal imaging guided cancer combination phototherapy, which are promising for the diagnosis and treatment of cancer.

Iron Metabolism in Cancer

Demanded as an essential trace element that supports cell growth and basic functions, iron can be harmful and cancerogenic though. By exchanging between its different oxidized forms, iron overload induces free radical formation, lipid peroxidation, DNA, and protein damages, leading to carcinogenesis or ferroptosis. Iron also plays profound roles in modulating tumor microenvironment and metastasis, maintaining genomic stability and controlling epigenetics. in order to meet the high requirement of iron, neoplastic cells have remodeled iron metabolism pathways, including acquisition, storage, and efflux, which makes manipulating iron homeostasis a considerable approach for cancer therapy. Several iron chelators and iron oxide nanoparticles (IONPs) has recently been developed for cancer intervention and presented considerable effects. This review summarizes some latest findings about iron metabolism function and regulation mechanism in cancer and the application of iron chelators and IONPs in cancer diagnosis and therapy.

Magnetic Drug Delivery: Where the Field Is Going

Targeted delivery of anticancer drugs is considered to be one of the pillars of cancer treatment as it could allow for a better treatment efficiency and less adverse effects. A promising drug delivery approach is magnetic drug targeting which can be realized if a drug delivery vehicle possesses a strong magnetic moment. Here, we discuss different types of magnetic nanomaterials which can be used as magnetic drug delivery vehicles, approaches to magnetic targeted delivery as well as promising strategies for the enhancement of the imaging-guided delivery and the therapeutic action.

A light-induced nitric oxide controllable release nano-platform based on diketopyrrolopyrrole derivatives for pH-responsive photodynamic/photothermal synergistic cancer therapy

Emerging treatment approaches, such as gas therapy (GT), photodynamic therapy (PDT) and photothermal therapy (PTT), have received widespread attention. The development of an intelligent multifunctional nano-platform responding to tumor microenvironments for multimodal therapy is highly desirable. Herein, a near-infrared (NIR) light-responsive nitric oxide (NO) photodonor (4-nitro-3-trifluoromethylaniline, NF) and a pH-sensitive group (dimethylaminophenyl) have been introduced into a diketopyrrolopyrrole core (denoted as DPP-NF). The DPP-NF nanoparticles (NPs) can be activated under weakly acidic conditions of lysosomes (pH 4.5-5.0) to generate reactive oxygen species (ROS) and enhance photothermal efficiency. The fluorescence detection demonstrated that NO controllable release can be realized by "on-off" switching of the NF unit under NIR light irradiation or dark conditions. The controllable NO release of DPP-NF NPs can not only trigger tumor cell death by DNA damage, but also overcome PDT inefficiencies caused by hypoxia in tumors. Additionally, DPP-NF NPs displayed 45.6% photothermal conversion efficiency, making them superior to other reported DPP derivatives. In vitro studies showed that DPP-NF NPs possessed low dark toxicity and high phototoxicity with a half-maximal inhibitory concentration of about 38 μg mL-1. In vivo phototherapy indicated that DPP-NF NPs exhibited excellent tumor phototherapeutic efficacy with passive targeting of the tumor site via the enhanced permeability and retention (EPR) effect. These results highlight that the nano-platform has promising potential for NO-mediated multimodal synergistic phototherapy in clinical settings.

Selective Growth Synthesis of Ternary Janus Nanoparticles for Imaging-Guided Synergistic Chemo- and Photothermal Therapy in the Second NIR Window

Multifunctional therapeutic agents in the second near-infrared (NIR-II) window have attracted wide attention on account of their synergetic properties for effective cancer therapy. Here, we construct a selective growth strategy for the first time to fabricate ternary Janus nanoparticles (JNPs) containing hemispherical MnO₂ at one side and Au core covered with CuS shell at opposite side. The obtained ternary JNPs are further modified with poly(ethylene glycol)thiol to enhance the stability and biocompatibility (designated as PEG-CuS-Au-MnO₂ ternary JNPs). The MnO₂ domain with mesoporous structures can serve as hydrophobic drug carriers and magnetic resonance (MR) imaging contrast agents. Meanwhile, the Au segment is used for X-ray computed tomography (CT) imaging. Moreover, the PEG-CuS-Au-MnO₂ ternary JNPs can conduct hyperthermia at 1064 nm in NIR-II window to ablate tumors in deep tissue, which is ascribed to the localized surface plasmon resonance coupling effect of the Au core and CuS domain. All of the results reveal that PEG-CuS-Au-MnO₂ ternary JNPs not only exhibit pre-eminent CT/MR imaging capabilities, but also provide high chemo-photothermal antitumor efficacy under the guidance of CT/MR imaging. Taking together, the PEG-CuS-Au-MnO₂ ternary JNPs can be regarded as a prospective therapeutic nanoplatform for dual-modal imaging-guided synergistic chemo-photothermal cancer therapy in the NIR-II window.

Iron Oxide Nanoparticles in Photothermal Therapy

Photothermal therapy is a kind of therapy based on increasing the temperature of tumoral cells above 42 °C. To this aim, cells must be illuminated with a laser, and the energy of the radiation is transformed in heat. Usually, the employed radiation belongs to the near-infrared radiation range. At this range, the absorption and scattering of the radiation by the body is minimal. Thus, tissues are almost transparent. To improve the efficacy and selectivity of the energy-to-heat transduction, a light-absorbing material, the photothermal agent, must be introduced into the tumor. At present, a vast array of compounds are available as photothermal agents. Among the substances used as photothermal agents, gold-based compounds are one of the most employed. However, the undefined toxicity of this metal hinders their clinical investigations in the long run. Magnetic nanoparticles are a good alternative for use as a photothermal agent in the treatment of tumors. Such nanoparticles, especially those formed by iron oxides, can be used in combination with other substances or used themselves as photothermal agents. The combination of magnetic nanoparticles with other photothermal agents adds more capabilities to the therapeutic system: the nanoparticles can be directed magnetically to the site of interest (the tumor) and their distribution in tumors and other organs can be imaged. When used alone, magnetic nanoparticles present, in theory, an important limitation: their molar absorption coefficient in the near infrared region is low. The controlled clustering of the nanoparticles can solve this drawback. In such conditions, the absorption of the indicated radiation is higher and the conversion of energy in heat is more efficient than in individual nanoparticles. On the other hand, it can be designed as a therapeutic system, in which the heat generated by magnetic nanoparticles after irradiation with infrared light can release a drug attached to the nanoparticles in a controlled manner. This form of targeted drug delivery seems to be a promising tool of chemo-phototherapy. Finally, the heating efficiency of iron oxide nanoparticles can be increased if the infrared radiation is combined with an alternating magnetic field.

Heating Induced by Therapeutic Ultrasound in the Presence of Magnetic Nanoparticles

The efficiency of ultrasound hyperthermia for anti-cancer treatments such as radiotherapy or chemotherapy can be improved by using sonosensitizers, which are materials that enhance the attenuation and dissipation of acoustic energy. We propose the use of magnetic nanoparticles as sonosensitizers because of their biocompatibility, nontoxicity, and common use in several medical applications. A magnetic material was synthetized and then incorporated in the form of a magnetic fluid in agar tissue-mimicking phantoms. Ultrasound hyperthermia studies were conducted at various ultrasound frequencies and concentrations of magnetic nanoparticles in the phantoms. The theoretical modeling based on a heat transfer equation and the experimental results show good agreement and confirm that the temperature rise during ultrasound heating in tissue-mimicking phantoms doped with sonosensitizers is greater than that in a pure agar phantom. Furthermore, on the basis of Pennes' bio-heat equation, which takes into consideration the blood perfusion and metabolic heat, the thermal dose and lesion shapes after sonication were determined for a hypothetical tissue.