Iron Oxide Nanoflowers @ CuS Hybrids for Cancer Tri-Therapy: Interplay of Photothermal Therapy, Magnetic Hyperthermia and Photodynamic Therapy

Using magnetic particle imaging systems to localize and guide magnetic hyperthermia treatment: tracers, hardware, and future medical applications

Magnetic fluid hyperthermia (MFH) treatment makes use of a suspension of superparamagnetic iron oxide nanoparticles, administered systemically or locally, in combination with an externally applied alternating magnetic field, to ablate target tissue by generating heat through a process called induction. The heat generated above the mammalian euthermic temperature of 37°C induces apoptotic cell death and/or enhances the susceptibility of the target tissue to other therapies such as radiation and chemotherapy. While most hyperthermia techniques currently in development are targeted towards cancer treatment, hyperthermia is also used to treat restenosis, to remove plaques, to ablate nerves and to alleviate pain by increasing regional blood flow. While RF hyperthermia can be directed invasively towards the site of treatment, non-invasive localization of heat through induction is challenging. In this review, we discuss recent progress in the field of RF magnetic fluid hyperthermia and introduce a new diagnostic imaging modality called magnetic particle imaging that allows for a focused theranostic approach encompassing treatment planning, treatment monitoring and spatially localized inductive heating.

Spatial focusing of magnetic particle hyperthermia

Magnetic particle hyperthermia is a promising cancer therapy, but a typical constraint of its applicability is localizing heat solely to malignant regions sparing healthy surrounding tissues. By simultaneous application of a constant magnetic field together with the hyperthermia inducing alternating magnetic field, heating focus may be confined to smaller regions in a tunable manner. The main objective of this work is to evaluate the focusing parameters, by adequate selection of magnetic nanoparticles and field conditions, and explore spatially focused magnetic particle hyperthermia efficiency in tissue phantom systems comprising agarose gel and magnetic nanoparticles. Our results suggest the possibility of spatially focused heating efficiency of magnetic nanoparticles through the application of a constant magnetic field. Tuning of the constant magnetic field parameters may result in minimizing thermal shock in surrounding regions without affecting the beneficiary thermal outcome in the focusing region.

PEGylated Bilirubin-coated Iron Oxide Nanoparticles as a Biosensor for Magnetic Relaxation Switching-based ROS Detection in Whole Blood

Rationale: Magnetic relaxation switching (MRSw) induced by target-triggered aggregation or dissociation of superparamagnetic iron oxide nanoparticles (SPIONs) have been utilized for detection of diverse biomarkers. However, an MRSw-based biosensor for reactive oxygen species (ROS) has never been documented.

Methods: To this end, we constructed a biosensor for ROS detection based on PEGylated bilirubin (PEG-BR)-coated SPIONs (PEG-BR@SPIONs) that were prepared by simple sonication via ligand exchange. In addition, near infra-red (NIR) fluorescent dye was loaded onto PEG-BR@SPIONs as a secondary option for fluorescence-based ROS detection.

Results: PEG-BR@SPIONs showed high colloidal stability under physiological conditions, but upon exposure to the model ROS, NaOCl, in vitro, they aggregated, causing a decrease in signal intensity in T2-weighted MR images. Furthermore, ROS-responsive PEG-BR@SPIONs were taken up by lipopolysaccharide (LPS)-activated macrophages to a much greater extent than ROS-unresponsive control nanoparticles (PEG-DSPE@SPIONs). In a sepsis-mimetic clinical setting, PEG-BR@SPIONs were able to directly detect the concentrations of ROS in whole blood samples through a clear change in T2 MR signals and a 'turn-on' signal of fluorescence.

Conclusions: These findings suggest that PEG-BR@SPIONs have the potential as a new type of dual mode (MRSw-based and fluorescence-based) biosensors for ROS detection and could be used to diagnose many diseases associated with ROS overproduction.

Nanoparticle-based Cell Trackers for Biomedical Applications

The continuous or real-time tracking of biological processes using biocompatible contrast agents over a certain period of time is vital for precise diagnosis and treatment, such as monitoring tissue regeneration after stem cell transplantation, understanding the genesis, development, invasion and metastasis of cancer and so on. The rationally designed nanoparticles, including aggregation-induced emission (AIE) dots, inorganic quantum dots (QDs), nanodiamonds, superparamagnetic iron oxide nanoparticles (SPIONs), and semiconducting polymer nanoparticles (SPNs), have been explored to meet this urgent need. In this review, the development and application of these nanoparticle-based cell trackers for a variety of imaging technologies, including fluorescence imaging, photoacoustic imaging, magnetic resonance imaging, magnetic particle imaging, positron emission tomography and single photon emission computing tomography are discussed in detail. Moreover, the further therapeutic treatments using multi-functional trackers endowed with photodynamic and photothermal modalities are also introduced to provide a comprehensive perspective in this promising research field.

The Role of Magnetic Nanoparticles in Cancer Nanotheranostics

Technological development is in constant progress in the oncological field. The search for new concepts and strategies for improving cancer diagnosis, treatment and outcomes constitutes a necessary and continuous process, aiming at more specificity, efficiency, safety and better quality of life of the patients throughout the treatment. Nanotechnology embraces these purposes, offering a wide armamentarium of nanosized systems with the potential to incorporate both diagnosis and therapeutic features, towards real-time monitoring of cancer treatment. Within the nanotechnology field, magnetic nanosystems stand out as complex and promising nanoparticles with magnetic properties, that enable the use of these constructs for magnetic resonance imaging and thermal therapy purposes. Additionally, magnetic nanoparticles can be tailored for increased specificity and reduced toxicity, and functionalized with contrast, targeting and therapeutic agents, revealing great potential as multifunctional nanoplatforms for application in cancer theranostics. This review aims at providing a comprehensive description of the current designs, characterization techniques, synthesis methods, and the role of magnetic nanoparticles as promising nanotheranostic agents. A critical appraisal of the impact, potentialities and challenges associated with each technology is also presented.

Enhanced Tumor Synergistic Therapy by Injectable Magnetic Hydrogel Mediated Generation of Hyperthermia and Highly Toxic Reactive Oxygen Species

Nanoparticle-mediated tumor magnetic induction hyperthermia has received tremendous attention. However, it has been a challenge to improve the efficacy at 42 °C therapeutic temperatures without resistance to induced thermal stress. Therefore, we designed a magnetic hydrogel nanozyme (MHZ) utilizing inclusion complexation between PEGylated nanoparticles and α-cyclodextrin, which can enhance tumor oxidative stress levels by generating reactive oxygen species through nanozyme-catalyzed reactions based on tumor magnetic hyperthermia. MHZ can be injected and diffused into the tumor tissue due to shear thinning as well as magnetocaloric phase transition properties, and magnetic heat generated by the Fe₃O₄ first gives 42 °C of hyperthermia to the tumor. Fe₃O₄ nanozyme exerts peroxidase-like properties in the acidic environment of tumor to generate hydroxyl radicals (^•OH) by the Fenton reaction. The hyperthermia promotes the enzymatic activity of Fe₃O₄ nanozyme to produce more ^•OH. Simultaneously, ^•OH further damages the protective heat shock protein 70, which is highly expressed in hyperthermia to enhance the therapeutic effect of hyperthermia. This single magnetic nanoparticle exerts dual functions of hyperthermia and catalytic therapy to synergistically treat tumors, overcoming the resistance of tumor cells to induced thermal stress without causing severe side effects to normal tissues at 42 °C hyperthermia.

Glutathione triggered degradation of polydopamine to facilitate controlled drug release for synergic combinational cancer treatment

Here we report a novel mechanism for triggering drug release in the polydopamine (PDA)-coated magnetic CuCo2S4 core-shell nanostructure by glutathione (GSH) triggered degradation of PDA for release. In the design, we used PDA coated CuCo2S4 as the nanocarrier with polyethylene glycol and folic acid targeting molecules to ensure the safe delivery of doxorubicin (DOX) to cancer cells. In addition, the controlled release could be enforced by taking advantage of the pH sensitivity of PDA to tumor acidic environments. The targeting and treatment of HeLa cancer cells were very effective and the killing was more efficient at higher levels of GSH. Furthermore, the designed system not only could be used for drug delivery but also could combine photothermal therapy with chemotherapy in a synergetic way. Plus, the system could be used for magnetic resonance imaging (MRI), which is beneficial for imaging-guided treatment.

Near-infrared photothermally activated nanomachines for cancer theragnosis

Near-infrared photothermal-activated nanomaterials are emerging as a promising tool in precise cancer theranostics. This Frontier article highlights the recent advances of photothermal-activated nanoagents in biomedical applications, namely photothermal-initiated drug/contrast agent release, gene silencing, programmed targeting and gas theranostics. In the end, we give a perspective on the further development of photothermal-sensitive nanomedicines.

Maghemite nanoparticles stabilize the protein corona formed with transferrin presenting different iron-saturation levels

Magnetic nanoparticles are ideal candidates for biomedical applications given their potential use in magnetic resonance imaging, magnetic hyperthermia and targeted drug delivery. Understanding protein-nanoparticle interactions in the blood stream is of major importance due to their potential risks, especially immunogenicity (i.e. the ability to induce an immune response). Here, we report on the interaction of superparamagnetic maghemite (γ-Fe2O3) nanoparticles with human blood plasma protein transferrin presenting different iron-saturation levels: partially iron-saturated (i.e. transferrin) and iron-free transferrin (i.e. apotransferrin). The nanoparticle-protein interaction and the protein corona formation were studied using biophysical and chemical approaches based on dynamic light scattering, gel electrophoresis, circular dichroism spectroscopy and differential scanning fluorimetry. We found that iron content governs the protein corona formation and induces a strong effect on the thermal stability of the bound protein. Our results demonstrate a stabilizing effect of the nanoparticles with a change of the unfolding position of approximately 10 °C towards higher temperatures for transferrin. Our study may be relevant for the further development of magnetic nanoparticles as diagnostic and therapeutic tools.

TRAIL acts synergistically with iron oxide nanocluster-mediated magneto- and photothermia

Targeting TRAIL (Tumor necrosis factor (TNF)-Related Apoptosis-Inducing Ligand) receptors for cancer therapy remains challenging due to tumor cell resistance and poor preparations of TRAIL or its derivatives. Herein, to optimize its therapeutic use, TRAIL was grafted onto iron oxide nanoclusters (NCs) with the aim of increasing its pro-apoptotic potential through nanoparticle-mediated magnetic hyperthermia (MHT) or photothermia (PT). Methods: The nanovector, NC@TRAIL, was characterized in terms of size, grafting efficiency, and potential for MHT and PT. The therapeutic function was assessed on a TRAIL-resistant breast cancer cell line, MDA-MB-231, wild type (WT) or TRAIL-receptor-deficient (DKO), by combining complementary methylene blue assay and flow cytometry detection of apoptosis and necrosis. Results: Combined with MHT or PT under conditions of "moderate hyperthermia" at low concentrations, NC@TRAIL acts synergistically with the TRAIL receptor to increase the cell death rate beyond what can be explained by the mere global elevation of temperature. In contrast, all results are consistent with the idea that there are hotspots, close to the nanovector and, therefore, to the membrane receptor, which cause disruption of the cell membrane. Furthermore, nanovectors targeting other membrane receptors, unrelated to the TNF superfamily, were also found to cause tumor cell damage upon PT. Indeed, functionalization of NCs by transferrin (NC@Tf) or human serum albumin (NC@HSA) induces tumor cell killing when combined with PT, albeit less efficiently than NC@TRAIL. Conclusions: Given that magnetic nanoparticles can easily be functionalized with molecules or proteins recognizing membrane receptors, these results should pave the way to original remote-controlled antitumoral targeted thermal therapies.

Construction of a Polypyrrole-Based Multifunctional Nanocomposite for Dual-Modal Imaging and Enhanced Synergistic Phototherapy against Cancer Cells

Design and construction of multifunctional theranostic nanoplatforms are still desired for cancer-effective treatment. Herein, a kind of polypyrrole (PPy)-based multifunctional nanocomposite was designed and successfully constructed for dual-model imaging and enhanced synergistic phototherapy against cancer cells. Through graphene oxide (GO) sheet coating, PPy nanoparticles (NPs) were effectively combined with polyethylene glycol chains, Au NPs, and IR820 molecules. The obtained PGPAI NPs showed promising ability for photoacoustic/computed tomography imaging. Under near-infrared light irradiation, the PPy core and IR820 molecule effectively generated heat and reactive oxygen species (ROS), respectively. Furthermore, the loaded Au NPs owning catalase-like activity produced oxygen by decomposing H₂O₂ (up-regulated in tumor region), enhancing the oxygen-dependent photodynamic therapy efficacy. The formed PGPAI NPs were also proved to own desirable photothermal conversion efficiency, photothermal stability, colloidal stability, cytocompatibility, and cellular internalization behaviors. Furthermore, cell assay demonstrated that PGPAI NPs displayed enhanced synergistic phototherapy efficacy against cancer cells. These developed multifunctional nanoplatforms are promising for effective cancer theranostic applications.

Use of magnetic fields and nanoparticles to trigger drug release and improve tumor targeting

Drug delivery strategies aim to maximize a drug's therapeutic index by increasing the concentration of drug at target sites while minimizing delivery to off-target tissues. Because biological tissues are minimally responsive to magnetic fields, there has been a great deal of interest in using magnetic nanoparticles in combination with applied magnetic fields to selectively control the accumulation and release of drug in target tissues while minimizing the impact on surrounding tissue. In particular, spatially variant magnetic fields have been used to encourage accumulation of drug-loaded magnetic nanoparticles at target sites, while time-variant magnetic fields have been used to induce drug release from thermally sensitive nanocarriers. In this review, we discuss nanoparticle formulations and approaches that have been developed for magnetic targeting and/or magnetically induced drug release, as well as ongoing challenges in using magnetism for therapeutic applications. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Copper sulfide: An emerging adaptable nanoplatform in cancer theranostics

Copper sulfide nanoparticles (CuS NPs), emerging nanoplatforms with dual diagnostic and therapeutic applications, are being actively investigated in this era of "war on cancer" owing to their versatility and adaptability. This article discusses the pros and cons of using CuS NPs in diagnostics, therapeutics, and theranostics. The first section introduces CuS NPs and discusses the features that render them more advantageous than other established nanoplatforms in cancer management. Subsequent sections include specific in vitro and in vivo results of different studies showing the potential of CuS NPs as nanoplatforms. Methods used for visualization (photoacoustic imaging and magnetic resonance imaging) of CuS NPs and treatment (phototherapy and combinatorial therapy) have also been discussed. Furthermore, the challenges and opportunities associated with using CuS NPs have been elucidated. Further investigations on CuS NPs are required to translate it for clinical applications.