Photothermia at the nanoscale induces ferroptosis via nanoparticle degradation

Substrate softness increases magnetic microdiscs-induced cytotoxicity

Cytotoxicity of nanoparticles is primarily assessed on cells grown in plastic culture plates, a mechanical environment that is a million times stiffer than most of the human tissues. Here we question whether nanoparticles cytotoxicity is sensitive to the stiffness of the extracellular environment. To this end, we compare the metabolic activity, the proliferation and death rates, and the motility of a glioblastoma cancer cell line and a fibroblast cell line exposed to gold-coated Ni80Fe20 microdiscs when grown on a glass substrate or on a soft substrate whose mechanical properties are close to physiology. Our main result is that cells grown on soft substrates take up more microdiscs which results in greater toxic effects, but also that toxicity at similar particle load is more pronounced on soft substrates especially at large concentration of nanoparticles. These results suggest that both microdiscs uptake and their intracellular processing differ between soft and rigid substrates.

Key factors influencing magnetic nanoparticle-based photothermal therapy: physicochemical properties, irradiation power, and particle concentration in vitro

A collection of magnetic nanoparticles with average particle sizes in the range between 9 and 78 nm were prepared using several synthetic approaches that also provided different particle morphologies (spherical, octahedral and flowers). Some of these particles were also subsequently coated with different molecules in order to generate a set of materials that allowed us to evaluate the impact that the particle size, shape and coating had on the heating capacity of the nanoparticles when exposed to near infrared (NIR) laser light. Moreover, one of the prepared materials (octahedral particles of ∼32 nm coated with dextran) was used to perform an in vitro assay to study the possible use of this material in the frame of photothermal treatments to trigger cell death. It was found that both the laser power and the particle concentration played a significant role in the reduction of the cell viability. Under the most extreme conditions of laser power and nanoparticle concentration, cell viability was reduced to 11% of the whole cell population using only 10 min exposure to laser light. These results open the possibility of further studies of photothermal treatments using magnetic nanoparticles, a material already approved for clinical practice.

Multiscale Thermal Analysis of Gold Nanostars in 3D Tumor Spheroids: Integrating Cellular-Level Photothermal Effects and Nanothermometry via X-Ray Spectroscopy

In the pursuit of enhancing cancer treatment efficacy while minimizing side effects, near-infrared (NIR) photothermal therapy (PTT) has emerged as a promising approach. By using photothermally active nanomaterials, PTT enables localized hyperthermia, effectively eliminating cancer cells with minimal invasiveness and toxicity. Among these nanomaterials, gold nanostars (AuNS) stand out due to their tunable plasmon resonance and efficient light absorption. This study addresses the challenge of measuring nanoscale temperatures during AuNS-mediated PTT by employing X-ray absorption spectroscopy (XAS) within 3D tumor spheroids. It also aims to investigate the heat generated at the nanoscale and the resultant biological damage observed at a larger scale, utilizing confocal microscopy to establish connections between AuNS heat generation, tissue damage, and their impacts on cellular structure. These nanoscale and microscale thermal effects have been compared with macroscopic values obtained from infrared thermography, as part of a multiscale thermal analysis. The findings underscore the efficacy of AuNS in enhancing PTT and provide insights into the spatial distribution of thermal effects within tumor tissues. This research advances the understanding of localized hyperthermia in cancer therapy and underscores the potential of AuNS-based PTT for clinical applications.

Elucidating the Dynamics of Biodegradation and Biosynthesis of Magnetic Nanoparticles in Human Stem Cells

Iron oxide nanoparticles, due to their magnetic properties, are versatile tools for biomedical applications serving both diagnostic and therapeutic roles. Their performance is intricately intertwined with their fate in the demanding biological environment. Once inside cells, these nanoparticles can be degraded, implying a loss of magnetic efficacy, but also transformed into neo-synthesized magnetic nanoparticles, potentially restoring functionality. This study aims to delineate biological features governing these processes. Magnetic nanoparticles are internalized in human mesenchymal stem cells (hMSCs), and their biotransformations are investigated from nano- to micro-scale using electron microscopy (STEM-HAADF, HRTEM, SAED), a benchtop magnetic sensor, and fine structural characterizations (synchrotron XRD, VSM). Results evidence a delicate equilibrium between the biodegradation and biosynthesis of magnetic nanoparticles, with biotransformation kinetics depending on cell density at magnetic labeling and on spatial cell configuration (monolayers vs spheroids). The biotransformed nanoparticles, composed of magnetite or maghemite, are localized within endosomal/lysosomal compartments and associated with the recruitment of ferritin proteins.

Advanced Nanomaterials for Cancer Therapy: Gold, Silver, and Iron Oxide Nanoparticles in Oncological Applications

Cancer remains one of the most challenging health issues globally, demanding innovative therapeutic approaches for effective treatment. Nanoparticles, particularly those composed of gold, silver, and iron oxide, have emerged as promising candidates for changing cancer therapy. This comprehensive review demonstrates the landscape of nanoparticle‐based oncological interventions, focusing on the remarkable advancements and therapeutic potentials of gold, silver, and iron oxide nanoparticles. Gold nanoparticles have garnered significant attention for their exceptional biocompatibility, tunable surface chemistry, and distinctive optical properties, rendering them ideal candidates for various cancer diagnostic and therapeutic strategies. Silver nanoparticles, renowned for their antimicrobial properties, exhibit remarkable potential in cancer therapy through multiple mechanisms, including apoptosis induction, angiogenesis inhibition, and drug delivery enhancement. With their magnetic properties and biocompatibility, iron oxide nanoparticles offer unique cancer diagnosis and targeted therapy opportunities. This review critically examines the recent advancements in the synthesis, functionalization, and biomedical applications of these nanoparticles in cancer therapy. Moreover, the challenges are discussed, including toxicity concerns, immunogenicity, and translational barriers, and ongoing efforts to overcome these hurdles are highlighted. Finally, insights into the future directions of nanoparticle‐based cancer therapy and regulatory considerations, are provided aiming to accelerate the translation of these promising technologies from bench to bedside.

Roadmap on magnetic nanoparticles in nanomedicine

Magnetic nanoparticles (MNPs) represent a class of small particles typically with diameters ranging from 1 to 100 nanometers. These nanoparticles are composed of magnetic materials such as iron, cobalt, nickel, or their alloys. The nanoscale size of MNPs gives them unique physicochemical (physical and chemical) properties not found in their bulk counterparts. Their versatile nature and unique magnetic behavior make them valuable in a wide range of scientific, medical, and technological fields. Over the past decade, there has been a significant surge in MNP-based applications spanning biomedical uses, environmental remediation, data storage, energy storage, and catalysis. Given their magnetic nature and small size, MNPs can be manipulated and guided using external magnetic fields. This characteristic is harnessed in biomedical applications, where these nanoparticles can be directed to specific targets in the body for imaging, drug delivery, or hyperthermia treatment. Herein, this roadmap offers an overview of the current status, challenges, and advancements in various facets of MNPs. It covers magnetic properties, synthesis, functionalization, characterization, and biomedical applications such as sample enrichment, bioassays, imaging, hyperthermia, neuromodulation, tissue engineering, and drug/gene delivery. However, as MNPs are increasingly explored forin vivoapplications, concerns have emerged regarding their cytotoxicity, cellular uptake, and degradation, prompting attention from both researchers and clinicians. This roadmap aims to provide a comprehensive perspective on the evolving landscape of MNP research.

Metal ion interference therapy: metal-based nanomaterial-mediated mechanisms and strategies to boost intracellular "ion overload" for cancer treatment

Metal ion interference therapy (MIIT) has emerged as a promising approach in the field of nanomedicine for combatting cancer. With advancements in nanotechnology and tumor targeting-related strategies, sophisticated nanoplatforms have emerged to facilitate efficient MIIT in xenografted mouse models. However, the diverse range of metal ions and the intricacies of cellular metabolism have presented challenges in fully understanding this therapeutic approach, thereby impeding its progress. Thus, to address these issues, various amplification strategies focusing on ionic homeostasis and cancer cell metabolism have been devised to enhance MIIT efficacy. In this review, the remarkable progress in Fe, Cu, Ca, and Zn ion interference nanomedicines and understanding their intrinsic mechanism is summarized with particular emphasis on the types of amplification strategies employed to strengthen MIIT. The aim is to inspire an in-depth understanding of MIIT and provide guidance and ideas for the construction of more powerful nanoplatforms. Finally, the related challenges and prospects of this emerging treatment are discussed to pave the way for the next generation of cancer treatments and achieve the desired efficacy in patients.

Iron Oxide Nanoparticles Inhibit Tumor Progression and Suppress Lung Metastases in Mouse Models of Breast Cancer

Systemic exposure to starch-coated iron oxide nanoparticles (IONPs) can stimulate antitumor T cell responses, even when little IONP is retained within the tumor. Here, we demonstrate in mouse models of metastatic breast cancer that IONPs can alter the host immune landscape, leading to systemic immune-mediated disease suppression. We report that a single intravenous injection of IONPs can inhibit primary tumor growth, suppress metastases, and extend survival. Gene expression analysis revealed the activation of Toll-like receptor (TLR) pathways involving signaling via Toll/Interleukin-1 receptor domain-containing adaptor-inducing IFN-β (TRIF), a TLR pathway adaptor protein. Requisite participation of TRIF in suppressing tumor progression was demonstrated with histopathologic evidence of upregulated IFN-regulatory factor 3 (IRF3), a downstream protein, and confirmed in a TRIF knockout syngeneic mouse model of metastatic breast cancer. Neither starch-coated polystyrene nanoparticles lacking iron, nor iron-containing dextran-coated parenteral iron replacement agent, induced significant antitumor effects, suggesting a dependence on the type of IONP formulation. Analysis of multiple independent clinical databases supports a hypothesis that upregulation of TLR3 and IRF3 correlates with increased overall survival among breast cancer patients. Taken together, these data support a compelling rationale to re-examine IONP formulations as harboring anticancer immune (nano)adjuvant properties to generate a therapeutic benefit without requiring uptake by cancer cells.

Boosting chemotherapy of bladder cancer cells by ferroptosis using intelligent magnetic targeting nanoparticles

A versatile nano-delivery platform was reported to enhance the tumor suppression effect of chemotherapy by augmenting tumor cells' ferroptosis. The platform consists of pomegranate-like magnetic nanoparticles (rPAE@SPIONs) fabricated by encapsulating superparamagnetic iron oxide nanoparticles (SPIONs) within a reduced poly(β-amino ester)s-PEG amphiphilic copolymer (rPAE). The resulting platform exhibits several functionalities. Firstly, it promotes the doxorubicin (DOX) release by leveraging the mild hyperthermia generated by NIR irradiation. Secondly, it triggers ferroptosis in tumor cells, inducing their demise. Thirdly, it induces polarization of macrophages towards an anti-tumor M1 phenotype, contributing to ferroptosis of tumor cells and enhanced tumor cell suppression. This study effectively capitalizes on the versatility of SPIONs and offers a simple yet powerful strategy for developing a new nanosized ferroptosis-inducing agent, ultimately improving the inhibition of bladder cancer cells.

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.