Superparamagnetic iron oxide nanoparticles as novel X-ray enhancer for low-dose radiation therapy

Sarcoma cell-specific radiation sensitization by titanate scrolled nanosheets: insights from physicochemical analysis and transcriptomic profiling

This study aimed to explore the potential of metal oxides such as Titanate Scrolled Nanosheets (TNs) in improving the radiosensitivity of sarcoma cell lines. Enhancing the response of cancer cells to radiation therapy is crucial, and one promising approach involves utilizing metal oxide nanoparticles. We focused on the impact of exposing two human sarcoma cell lines to both TNs and ionizing radiation (IR). Our research was prompted by previous in vitro toxicity assessments, revealing a correlation between TNs' toxicity and alterations in intracellular calcium homeostasis. A hydrothermal process using titanium dioxide powder in an alkaline solution produced the TNs. Our study quantified the intracellular content of TNs and analyzed their impact on radiation-induced responses. This assessment encompassed PIXE analysis, cell proliferation, and transcriptomic analysis. We observed that sarcoma cells internalized TNs, causing alterations in intracellular calcium homeostasis. We also found that irradiation influence intracellular calcium levels. Transcriptomic analysis revealed marked disparities in the gene expression patterns between the two sarcoma cell lines, suggesting a potential cell-line-dependent nano-sensitization to IR. These results significantly advance our comprehension of the interplay between TNs, IR, and cancer cells, promising potential enhancement of radiation therapy efficiency.

Radiosensitizing Effect of Dextran-Coated Iron Oxide Nanoparticles on Malignant Glioma Cells

The potential of standard methods of radiation therapy is limited by the dose that can be safely delivered to the tumor, which could be too low for radical treatment. The dose efficiency can be increased by using radiosensitizers. In this study, we evaluated the sensitizing potential of biocompatible iron oxide nanoparticles coated with a dextran shell in A172 and Gl-Tr glioblastoma cells in vitro. The cells preincubated with nanoparticles for 24 h were exposed to ionizing radiation (X-ray, gamma, or proton) at doses of 0.5-6 Gy, and their viability was assessed by the Resazurin assay and by staining of the surviving cells with crystal violet. A statistically significant effect of radiosensitization by nanoparticles was observed in both cell lines when cells were exposed to 35 keV X-rays. A weak radiosensitizing effect was found only in the Gl-Tr line for the 1.2 MeV gamma irradiation and there was no radiosensitizing effect in both lines for the 200 MeV proton irradiation at the Bragg peak. A slight (ca. 10%) increase in the formation of additional reactive oxygen species after X-ray irradiation was found when nanoparticles were present. These results suggest that the nanoparticles absorbed by glioma cells can produce a significant radiosensitizing effect, probably due to the action of secondary electrons generated by the magnetite core, whereas the dextran shell of the nanoparticles used in these experiments appears to be rather stable under radiation exposure.

Prospects of nanoparticle-based radioenhancement for radiotherapy

Radiotherapy is a key pillar of solid cancer treatment. Despite a high level of conformal dose deposition, radiotherapy is limited due to co-irradiation of organs at risk and subsequent normal tissue toxicities. Nanotechnology offers an attractive opportunity for increasing the efficacy and safety of cancer radiotherapy. Leveraging the freedom of design and the growing synthetic capabilities of the nanomaterial-community, a variety of engineered nanomaterials have been designed and investigated as radiosensitizers or radioenhancers. While research so far has been primarily focused on gold nanoparticles and other high atomic number materials to increase the absorption cross section of tumor tissue, recent studies are challenging the traditional concept of high-Z nanoparticle radioenhancers and highlight the importance of catalytic activity. This review provides a concise overview on the knowledge of nanoparticle radioenhancement mechanisms and their quantification. It critically discusses potential radioenhancer candidate materials and general design criteria for different radiation therapy modalities, and concludes with research priorities in order to advance the development of nanomaterials, to enhance the efficacy of radiotherapy and to increase at the same time the therapeutic window.

Study of the mechanism underlying the role of PINK1/Parkin in the formic acid-induced autophagy of PC12 cells

This study aimed to explore PINK1/Parkin's role in methanol metabolite formic acid-induced autophagy in PC12 cells and provide a theoretical basis for elucidating methanol-induced neurotoxicity. After treatment with different formic acid concentrations, we observed the morphology and mitochondria of PC12 cells. We used an ultra-micro enzyme kit to detect the mitochondrial Na⁺ -K⁺ -ATPase and Ca²⁺ -Mg²⁺ -ATPase activities; a JC-1 kit to detect changes in the mitochondrial membrane potential (MMP); MDC staining to detect the autophagy levels; and western blotting to measure the expression levels of the mitochondrial marker protein COX IV and the autophagy-related proteins Beclin1, P62 and LC3II/LC3I, and the mitochondrial and cytoplasmic levels of PINK1, Parkin and P-Parkin. Compared with the control group, the mitochondrial diameters, the mitochondrial Na⁺ -K⁺ -ATP and Ca²⁺ -Mg²⁺ -ATPase activities, the MMP, and the COX IV expression levels decreased significantly (P < 0.05). The fluorescence signal intensity (indicating autophagy); relative Beclin1 and LC3II/LC3I protein expression levels; and relative mitochondrial PINK1, Parkin and P-Parkin levels increased significantly, and the relative P62 protein expression levels and relative cytoplasmic PINK1, Parkin and P-Parkin levels decreased significantly (P < 0.05) compared with the control group. Thus, formic acid alters mitochondrial morphology, causes mitochondrial dysfunction, affects the PINK/Parkin pathway and, thus, activates the process of mitochondrial autophagy.

In Vitro Analysis of Superparamagnetic Iron Oxide Nanoparticles Coated with APTES as Possible Radiosensitizers for HNSCC Cells

Superparamagnetic iron oxide nanoparticles (SPION) are being investigated for many purposes, e.g., for the amplification of ionizing radiation and for the targeted application of therapeutics. Therefore, we investigated SPIONs coated with (3-Aminopropyle)-Triethoxysilane (SPION-APTES) for their influence on different head and neck squamous cell carcinoma (HNSCC) cell lines, as well as for their suitability as a radiosensitizer. We used 24-well microscopy and immunofluorescence microscopy for cell observation, growth curves to determine cytostatic effects, and colony formation assays to determine cytotoxicity. We found that the APTES-SPIONs were very well taken up by the HNSCC cells. They generally have a low cytotoxic effect, showing no significant difference in clonogenic survival between the control group and cells treated with 20 µg Fe/mL (p > 0.25) for all cell lines. They have a cytostatic effect on some cell lines cells (e.g., Cal33) that is visible across different radiation doses (1, 2, 8 Gy, p = 0.05). In Cal33, e.g., SPION-APTES raised the doubling time at 2 Gy from 24.53 h to 41.64 h. Importantly, these findings vary notably between the cell lines. However, they do not significantly alter the radiation effect: only one out of eight cell lines treated with SPION-APTES showed a significantly reduced clonogenic survival after ionizing radiation with 2 Gy, and only two showed significantly reduced doubling times. Thus, although the APTES-SPIONs do not qualify as a radiosensitizer, we were still able to vividly demonstrate and analyze the effect that the APTES-SPIONs have on various cell lines as a contribution to further functionalization.

Advances in the Mechanistic Understanding of Iron Oxide Nanoparticles' Radiosensitizing Properties

Among the plethora of nanosystems used in the field of theranostics, iron oxide nanoparticles (IONPs) occupy a central place because of their biocompatibility and magnetic properties. In this study, we highlight the radiosensitizing effect of two IONPs formulations (namely 7 nm carboxylated IONPs and PEG₅₀₀₀-IONPs) on A549 lung carcinoma cells when exposed to 225 kV X-rays after 6 h, 24 h and 48 h incubation. The hypothesis that nanoparticles exhibit their radiosensitizing effect by weakening cells through the inhibition of detoxification enzymes was evidenced by thioredoxin reductase activity monitoring. In particular, a good correlation between the amplification effect at 2 Gy and the residual activity of thioredoxin reductase was observed, which is consistent with previous observations made for gold nanoparticles (NPs). This emphasizes that NP-induced radiosensitization does not result solely from physical phenomena but also results from biological events.

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

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

Nontoxic In Vivo Clearable Nanoparticle Clusters for Theranostic Applications

Disintegrable inorganic nanoclusters (GIONs) with gold seed (GS) coating of an iron oxide core with a primary nanoparticle size less than 6 nm were prepared for theranostic applications. The GIONs possessed a broad near-infrared (NIR) absorbance at ∼750 nm because of plasmon coupling between closely positioned GSs on the iron oxide nanoclusters (ION) surface, in addition to the ∼513 nm peak corresponding to the isolated GS. The NIR laser-triggered photothermal response of GIONs was found to be concentration-dependent with a temperature rise of ∼8.5 and ∼4.5 °C from physiological temperature for 0.5 and 0.25 mg/mL, respectively. The nanoclusters were nonhemolytic and showed compatibility with human umbilical vein endothelial cells up to a concentration of 0.7 mg/mL under physiological conditions. The nanoclusters completely disintegrated at a lysosomal pH of 5.2 within 1 month. With an acute increase of over 400% intracellular reactive oxygen species soon after γ-irradiation and assistance from Fenton reaction-mediated supplemental oxidative stress, GION treatment in conjunction with radiation killed ∼50% of PLC/PRF/5 hepatoma cells. Confocal microscopy images of these cells showed significant cytoskeletal and nuclear damage from radiosensitization with GIONs. The cell viability further decreased to ∼10% when they were sequentially exposed to the NIR laser followed by γ-irradiation. The magnetic and optical properties of the nanoclusters enabled GIONs to possess a T₂ relaxivity of ∼223 mM^-1 s^-1and a concentration-dependent strong photoacoustic signal toward magnetic resonance and optical imaging. GIONs did not incur any organ damage or evoke an acute inflammatory response in healthy C57BL/6 mice. Elemental analysis of various organs indicated differential clearance of gold and iron via both renal and hepatobiliary routes.

Biocompatible polymer-modified gold nanocomposites of different shapes as radiation sensitizers

Radiation therapy is a powerful approach for cancer treatment due to its low invasiveness. The development of radiation sensitizers is of great importance as they assist in providing radiation therapy at a low dose. In this study, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-modified gold nanocomposites of different shapes were created using the grafting-to approach to serve as a novel radiation sensitizer with high cellular uptake. The effect of the shape of the nanocomposite on cellular uptake by the breast cancer cell line MCF-7 was also investigated. The PMPC-modified gold nanostars showed the highest cellular uptake compared to the other gold nanocomposites (spheres and rods), whereas cell cytotoxicity was negligible among all candidates. Furthermore, the therapeutic effect of radiation of PMPC-modified nanostars was the highest among all the gold nanocomposites. These results clearly indicate that the shape of the gold nanocomposite is an important parameter for cellular uptake and radiation sensitizing effects in breast cancer cells.

Gafchromic™ EBT3 Film Measurements of Dose Enhancement Effects by Metallic Nanoparticles for 192Ir Brachytherapy, Proton, Photon and Electron Radiotherapy

Interest in combining metallic nanoparticles, such as iron (SPIONs), gold (AuNPs) and bismuth oxide (BiONPs), with radiotherapy has increased due to the promising therapeutic advantages. While the underlying physical mechanisms of NP-enhanced radiotherapy have been extensively explored, only a few research works were motivated to quantify its contribution in an experimental dosimetry setting. This work aims to explore the feasibility of radiochromic films to measure the physical dose enhancement (DE) caused by the release of secondary electrons and photons during NP–radiotherapy interactions. A 10 mM each of SPIONs, AuNPs or BiONPs was loaded into zipper bags packed with GAFCHROMIC™ EBT3 films. The samples were exposed to a single radiation dose of 4.0 Gy with clinically relevant beams. Scanning was conducted using a flatbed scanner in red-component analysis for optimum sensitivity. Experimental dose enhancement factors (DEFExperimental) were then calculated using the ratio of absorbed doses (with/without NPs) converted from the films’ calibration curves. DEFExperimental for all NPs showed no significant physical DE beyond the uncertainty limits (p > 0.05). These results suggest that SPIONs, AuNPs and BiONPs might potentially enhance the dose in these clinical beams. However, changes in NPs concentration, as well as dosimeter sensitivity, are important to produce observable impact.

Pulmonary Delivery of Theranostic Nanoclusters for Lung Cancer Ferroptosis with Enhanced Chemodynamic/Radiation Synergistic Therapy

Inefficient tumor accumulation and penetration remain as the main challenges to therapy efficacy of lung cancer. Local delivery of smart nanoclusters can increase drug penetration and provide superior antitumor effects than systemic routes. Here, we report self-assembled pH-sensitive superparamagnetic iron oxide nanoclusters (SPIONCs) that enhance in situ ferroptosis and apoptosis with radiotherapy and chemodynamic therapy. After pulmonary delivery in orthotopic lung cancer, SPIONCs disintegrate into smaller nanoparticles and release more iron ions in an acidic microenvironment. Under single-dose X-ray irradiation, endogenous superoxide dismutase converts superoxide radicals produced by mitochondria to hydrogen peroxide, which in turn generates hydroxyl radicals by the Fenton reaction from iron ions accumulated inside the tumor. Finally, irradiation and iron ions enhance tumor lipid peroxidation and induce cell apoptosis and ferroptosis. Thus, rationally designed pulmonary delivered nanoclusters provide a promising strategy for noninvasive imaging of lung cancer and synergistic therapy.

Nanoparticle radiosensitization: from extended local effect modeling to a survival modification framework of compound Poisson additive killing and its carbon dots validation

Objective. To construct an analytical model instead of local effect modeling for the prediction of the biological effectiveness of nanoparticle radiosensitization. Approach. An extended local effects model is first proposed with a more comprehensive description of the nanoparticles mediated local killing enhancements, but meanwhile puts forward challenging issues that remain difficult and need to be further studied. As a novel method instead of local effect modeling, a survival modification framework of compound Poisson additive killing is proposed, as the consequence of an independent additive killing by the assumed equivalent uniform doses of individual nanoparticles per cell under the LQ model. A compound Poisson killing (CPK) model based on the framework is thus derived, giving a general expression of nanoparticle mediated LQ parameter modification. For practical use, a simplified form of the model is also derived, as a concentration dependent correction only to the α parameter, with the relative correction (α″/α) dominated by the mean number, and affected by the agglomeration of nanoparticles per cell. For different agglomeration state, a monodispersion model of the dispersity factor η = 1, and an agglomeration model of 2/3 < η < 1, are provided for practical prediction of (α″/α) value respectively. Main results. Initial validation by the radiosensitization of HepG2 cells by carbon dots showed a high accuracy of the CPK model. In a safe range of concentration (0.003–0.03 μg μl−1) of the carbon dots, the prediction errors of the monodispersion and agglomeration models were both within 2%, relative to the clonogenic survival data of the sensitized HepG2 cells. Significance. The compound Poisson killing model provides a novel approach for analytical prediction of the biological effectiveness of nanoparticle radiosensitization, instead of local effect modeling.

A Pre-clinical Trial Study: Anti-human Colon Cancer Effect of Thalassiolin B in vitro with Enzymes Inhibition Effects and Molecular Docking Studies

In this study, it is recorded the inhibition effect of Thalassiolin B on aldose reductase, alpha-glucosidase and alpha-amylase enzymes. In the next step, the molecular docking method was used to compare the biological activities of the Thalassiolin B molecule against enzymes formed from the assembly of proteins. In these calculations, the enzymes used are Aldose reductase, Alpha-Amylase, and Alpha-Glucosidase, respectively. After the docking method, ADME/T analysis of Thalassiolin B molecule was performed to be used as a drug in the pharmaceutical industry. In the MTT assay, the anti-human colon cancer properties of Thalassiolin B against EB, LS1034, and SW480 cell lines were investigated. The cell viability of Thalassiolin B was very low against human colon cancer cell lines without any cytotoxicity on the human normal (HUVEC) cell line. The IC₅₀ of the Thalassiolin B against EB, LS1034, and SW480 were 483, 252, and 236 µg/mL, respectively. Thereby, the best cytotoxicity results and anti-human colon cancer potentials of our Thalassiolin B were observed in the case of the SW480 cell line. Maybe the anti-human colon cancer properties of Thalassiolin B are related to their antioxidant effects.

Radiation nanosensitizers in cancer therapy-From preclinical discoveries to the outcomes of early clinical trials

Improving the efficacy and spatial targeting of radiation therapy while sparing surrounding normal tissues has been a guiding principle for its use in cancer therapy. Nanotechnologies have shown considerable growth in terms of innovation and the development of new therapeutic approaches, particularly as radiosensitizers. The aim of this study was to systematically review how nanoparticles (NPs) are used to enhance the radiotherapeutic effect, including preclinical and clinical studies. Clinicaltrials.gov was used to perform the search using the following terms: radiation, cancer, and NPs. In this review, we describe the various designs of nano-radioenhancers, the rationale for using such technology, as well as their chemical and biological effects. Human trials are then discussed with an emphasis on their design and detailed clinical outcomes.

Using a Hybrid Radioenhancer to Discover Tumor Cell-targeted Treatment for Osteosarcoma: An In Vitro Study

Osteosarcoma is insensitive to radiation. High-dose radiation is often used as a treatment but causes side effects in patients. Hence, it is important to develop tumor cell-- targeted radiotherapy that could improve radiotherapy efficiency on tumor cells and reduce the toxic effect on normal cells during radiation treatment. In this study, we developed an innovative method for treating osteosarcoma by using a novel radiation-enhancer (i.e., carboxymethyl-hexanoyl chitosan-coated self-assembled Au@Fe3O4 nanoparticles; CSAF NPs). CSAF NPs were employed together with 5-aminolevulinic acid (5- ALA) to achieve tumor cell-targeted radiotherapy. In this study, osteosarcoma cells (MG63) and normal cells (MC3T3-E1) were used for an in vitro investigation, in which reactive oxygen species (ROS) assay, cell viability assay, clonogenic assay, and western blot were used to confirm the treatment efficiency. The ROS assay showed that the combination of CSAF NPs and 5-ALA enhanced radiation-induced ROS production in tumor cells (MG63); however, this was not observed in normal cells (MC3T3-E1). The cell viability ratio of normal cells to tumor cells after treatment with CSAF NPs and 5-ALA reached 2.79. Moreover, the clonogenic assay showed that the radiosensitivity of MG63 cells was increased by the combination use of CSAF NPs and 5-ALA. This was supported by performing a western blot that confirmed the expression of cytochrome c (a marker of cell mitochondria damage) and caspase-3 (a marker of cell apoptosis). The results provide an essential basis for developing tumor-cell targeted radiotherapy by means of low-- dose radiation.

Intracellular Delivery of Doxorubicin by Iron Oxide-Based Nano-Constructs Increases Clonogenic Inactivation of Ionizing Radiation in HeLa Cells

In this study, we determined the potential of polyethylene glycol-encapsulated iron oxide nanoparticles (IONP_CO) for the intracellular delivery of the chemotherapeutic doxorubicin (IONP_DOX) to enhance the cytotoxic effects of ionizing radiation. The biological effects of IONP and X-ray irradiation (50 kV and 6 MV) were determined in HeLa cells using the colony formation assay (CFA) and detection of γH2AX foci. Data are presented as mean ± SEM. IONP were efficiently internalized by HeLa cells. IONP_CO radiomodulating effect was dependent on nanoparticle concentration and photon energy. IONP_CO did not radiosensitize HeLa cells with 6 MV X-rays, yet moderately enhanced cellular radiosensitivity to 50 kV X-rays (DMF_SF0.1 = 1.13 ± 0.05 (p = 0.01)). IONP_DOX did enhance the cytotoxicity of 6 MV X-rays (DMF_SF0.1 = 1.3 ± 0.1; p = 0.0005). IONP treatment significantly increased γH2AX foci induction without irradiation. Treatment of HeLa cells with IONP_CO resulted in a radiosensitizing effect for low-energy X-rays, while exposure to IONP_DOX induced radiosensitization compared to IONP_CO in cells irradiated with 6 MV X-rays. The effect did not correlate with the induction of γH2AX foci. Given these results, IONP are promising candidates for the controlled delivery of DOX to enhance the cytotoxic effects of ionizing radiation.

Liposome technologies towards colorectal cancer therapeutics

Colorectal cancer (CRC) is the third most common cancer and the fourth most common deadly cancer worldwide. After treatment with curative intent recurrence rates vary with staging 0-13% in Stage 1, 11-61% in S2 and 28-73% in Stage 3. The toxicity to healthy tissues from chemotherapy and radiotherapy and drug resistance severely affect the quality of life and cancer specific outcomes of CRC patients. To overcome some of these limitations, many efforts have been made to develop nanomaterial-based drug delivery systems. Among these nanocarriers, liposomes represented one of the most successful candidates in delivering targeted oncological treatment, improving safety profile and therapeutic efficacy of encapsulated drugs. In this review we will discuss liposome design with a particular focus on the targeting feature and triggering functions. We will also summarise the recent advances in liposomal delivery system for CRC treatment in both the preclinical and clinical studies. We will finally provide our perspectives on the liposome technology development for the future clinical translation. STATEMENT OF SIGNIFICANCE: Conventional treatments for colorectal cancer (CRC) severely affect the therapeutic effects for advanced patients. With the development of nanomedicines, liposomal delivery system appears to be one of the most promising nanocarriers for CRC treatment. In last three years several reviews in this area have been published focusing on the preclinical research and drug delivery function, which is a fairly narrow focus in the field of liposome technology for CRC therapy. Our review presented the most recent advances of the liposome technology (both clinical and preclinical applications) for CRC with strong potential for further clinical translation. We believe it will attract lots of attention from various audiences, including researchers, clinicians and the industry.

Caffeic Acid, Quercetin and 5-Fluorocytidine-Functionalized Au-Fe3O4 Nanoheterodimers for X-ray-Triggered Drug Delivery in Breast Tumor Spheroids

Au-Fe3O4 nanoheterodimers (NHD) were functionalized with the natural and synthetic anticancer drugs caffeic acid (CA), quercetin (Q) and 5-fluorocytidine (5FC). Their X-radiation dose-enhancing potential and chemotherapeutic efficacy for bimodal cancer therapy were investigated by designing multicellular tumor spheroids (MCTS) to in vitro avascular tumor models. MCTS were grown from the breast cancer cell lines MCF-7, MDA-MB-231, and MCF-10A. The MCF-7, MDA-MB-231 and MCF-10A MCTS were incubated with NHD-CA, NHD-Q, or NHD-5FC and then exposed to fractionated X-radiation comprising either a single 10 Gy dose, 2 daily single 5 Gy doses or 5 daily single 2 Gy doses. The NHD-CA, NHD-Q, and NHD-5FC affected the growth of X-ray irradiated and non-irradiated MCTS in a different manner. The impact of the NHDs on the glycolytic metabolism due to oxygen deprivation inside MCTS was assessed by measuring lactate secretion and glucose uptake by the MCTS. The NHD-CA and NHD-Q were found to act as X-radiation dose agents in MCF-7 MCTS and MDA-MB-231 MCTS and served as radioprotector in MCF-10A MCTS. X-ray triggered release of CA and Q inhibited lactate secretion and thereupon disturbed glycolytic reprogramming, whereas 5FC exerted their cytotoxic effects on both, healthy and tumor cells, after their release into the cytosol.

Ferrite Nanoparticles-Based Reactive Oxygen Species-Mediated Cancer Therapy

Ferrite nanoparticles have been widely used in the biomedical field (such as magnetic targeting, magnetic resonance imaging, magnetic hyperthermia, etc.) due to their appealing magnetic properties. In tumor acidic microenvironment, ferrite nanoparticles show intrinsic peroxidase-like activities, which can catalyze the Fenton reaction of hydrogen peroxide (H₂O₂) to produce highly toxic hydroxyl free radicals (•OH), causing the death of tumor cell. Recent progresses in this field have shown that the enzymatic activity of ferrite can be improved via converting external field energy such as alternating magnetic field and near-infrared laser into nanoscale heat to produce more •OH, enhancing the killing effect on tumor cells. On the other hand, combined with other nanomaterials or drugs for cascade reactions, the production of reactive oxygen species (ROS) can also be increased to obtain more efficient cancer therapy. In this review, we will discuss the current status and progress of the application of ferrite nanoparticles in ROS-mediated cancer therapy and try to provide new ideas for this area.

Oxi-Redox Selective Breast Cancer Treatment: An In Vitro Study of Theranostic In-Based Oxide Nanoparticles for Controlled Generation or Prevention of Oxidative Stress

In this article, we demonstrate that specifically engineered oxide nanoparticles (NPs) have the potential to act as theranostic materials that are able to generate or prevent oxidative stress through their oxi-redox activity in various types of malignant and nonmalignant cells. The oxi-redox activity is related to the type and presence of surface defects, which is modified with appropriate synthesis conditions. In the present work, we used MDA-MB-231 and MCF-7 human breast cancer cells and nonmalignant MCF-10A human breast cells to demonstrate how controlled oxidative stress mediated by specifically nanoengineered indium tin oxide (ITO) NPs can selectively induce cell death in the cancer cells while reducing the oxidative stress in the normal cells and supporting their proliferation. The ITO NPs are also promising nanotheranostic materials for cancer therapy and contrast agents because of their multimodal imaging capabilities. We demonstrate that the synthesized ITO NPs can selectively increase the generation of reactive oxygen species (ROS) in both breast tumor cell lines, resulting in activation of apoptosis, and can also greatly suppress the cellular proliferation in both types of tumor cells. In contrast, the ITO NPs exhibit ROS scavenging-like behavior, significantly decreasing the ROS levels in MCF-10A cells exposed to the additional ROS, hydrogen peroxide (H₂O₂), so that they protect the proliferation of nonmalignant MCF-10A cells from ROS damage. In addition, fluorescent microscopy images revealed that the ITO NPs emit strong fluorescence that could be used to reveal their location. Moreover, computed tomography imaging demonstrated that the ITO NPs exhibited a comparable capability toward anatomical contrast enhancement. These results suggest that the synthesized ITO NPs have the potential to be a novel selective therapeutic agent with a multimodal imaging property for anticancer treatment.

Roadmap for metal nanoparticles in radiation therapy: current status, translational challenges, and future directions

This roadmap outlines the potential roles of metallic nanoparticles (MNPs) in the field of radiation therapy. MNPs made up of a wide range of materials (from Titanium, Z = 22, to Bismuth, Z = 83) and a similarly wide spectrum of potential clinical applications, including diagnostic, therapeutic (radiation dose enhancers, hyperthermia inducers, drug delivery vehicles, vaccine adjuvants, photosensitizers, enhancers of immunotherapy) and theranostic (combining both diagnostic and therapeutic), are being fabricated and evaluated. This roadmap covers contributions from experts in these topics summarizing their view of the current status and challenges, as well as expected advancements in technology to address these challenges.

Encapsulation of Hydrophobic Drugs in Shell-by-Shell Coated Nanoparticles for Radio-and Chemotherapy-An In Vitro Study

Our research objective was to develop novel drug delivery vehicles consisting of TiO₂ and Al₂O₃ nanoparticles encapsulated by a bilayer shell that allows the reversible embedment of hydrophobic drugs. The first shell is formed by covalent binding of hydrophobic phosphonic acid at the metal oxide surface. The second shell composed of amphiphilic sodium dodecylbenzenesulfonate emerges by self-aggregation driven by hydrophobic interactions between the dodecylbenzene moiety and the hydrophobic first shell. The resulting double layer provides hydrophobic pockets suited for the intake of hydrophobic drugs. The nanoparticles were loaded with the anticancer drugs quercetin and 7-amino-4-methylcoumarin. Irradiation with X-rays was observed to release the potential anticancer drugs into the cytoplasm. In Michigan Cancer Foundation (MCF)-10 A cells, quercetin and 7-amino-4-methylcoumarin acted as antioxidants by protecting the non-tumorigenic cells from harmful radiation effects. In contrast, these agents increased the reactive oxygen species (ROS) formation in cancerous MCF-7 cells. Quercetin and 7-amino-4-methylcoumarin were shown to induce apoptosis via the mitochondrial pathway in cancer cells by determining an increase in TUNEL-positive cells and a decrease in mitochondrial membrane potential after irradiation. After X-ray irradiation, the survival fraction of MCF-7 cells with drug-loaded nanoparticles considerably decreased, which demonstrates the excellent performance of the double-layer stabilized nanoparticles as drug delivery vehicles.

Shell-by-Shell Functionalization of Inorganic Nanoparticles

The current state of the hierarchical chemical functionalization of inorganic nanoparticles (NPs) by shell-by-shell (SbS)-assembly of organic layers around the NP cores is summarized. This supramolecular functionalization concept is based on two steps: 1) the covalent grafting of a first ligand-shell consisting of, for example, long chain phosphonic acids and 2) the noncovalent interdigitation of amphiphiles forming the second ligand shell. The latter process is guaranteed predominantly by solvophobic interactions. These highly order organic-inorganic hybrid architectures are currently an emerging field at the interface of synthetic chemistry, nanotechnology, and materials science. The doubly functionalized NPs display tunable materials properties, such a controlled dispersibility and stability in various solvents, highly efficient trapping of guest molecules in between the ligand shells (water cleaning) as well as compartmentalization and modification of electronic interactions between photoactive components integrated in such complex nano-architectures. Such SbS-functionalized NPs have a high potential as water-cleaning materials and also some first prototype applications as biomedicinal therapeutics have been presented.

Human Serum Albumin in the Presence of AGuIX Nanoagents: Structure Stabilisation without Direct Interaction

The gadolinium-based nanoagent named AGuIX^® is a unique radiosensitizer and contrast agent which improves the performance of radiotherapy and medical imaging. Currently tested in clinical trials, AGuIX^® is administrated to patients via intravenous injection. The presence of nanoparticles in the blood stream may induce harmful effects due to undesired interactions with blood components. Thus, there is an emerging need to understand the impact of these nanoagents when meeting blood proteins. In this work, the influence of nanoagents on the structure and stability of the most abundant blood protein, human serum albumin, is presented. Synchrotron radiation circular dichroism showed that AGuIX^® does not bind to the protein, even at the high ratio of 45 nanoparticles per protein at 3 mg/L. However, it increases the stability of the albumin. Isothermal thermodynamic calorimetry and fluorescence emission spectroscopy demonstrated that the effect is due to preferential hydration processes. Thus, this study confirms that intravenous injection of AGuIX^® presents limited risks of perturbing the blood stream. In a wider view, the methodology developed in this work may be applied to rapidly evaluate the impact and risk of other nano-products that could come into contact with the bloodstream.

Efficient uptake and retention of iron oxide-based nanoparticles in HeLa cells leads to an effective intracellular delivery of doxorubicin

The purpose of this study was to construct and characterize iron oxide nanoparticles (IONP_CO) for intracellular delivery of the anthracycline doxorubicin (DOX; IONP_DOX) in order to induce tumor cell inactivation. More than 80% of the loaded drug was released from IONP_DOX within 24 h (100% at 70 h). Efficient internalization of IONP_DOX and IONP_CO in HeLa cells occurred through pino- and endocytosis, with both IONP accumulating in a perinuclear pattern. IONP_CO were biocompatible with maximum 27.9% ± 6.1% reduction in proliferation 96 h after treatment with up to 200 µg/mL IONP_CO. Treatment with IONP_DOX resulted in a concentration- and time-dependent decrease in cell proliferation (IC₅₀ = 27.5 ± 12.0 μg/mL after 96 h) and a reduced clonogenic survival (surviving fraction, SF = 0.56 ± 0.14; versus IONP_CO (SF = 1.07 ± 0.38)). Both IONP constructs were efficiently internalized and retained in the cells, and IONP_DOX efficiently delivered DOX resulting in increased cell death vs IONP_CO.

Chemical Mechanisms of Nanoparticle Radiosensitization and Radioprotection: A Review of Structure-Function Relationships Influencing Reactive Oxygen Species

Metal nanoparticles are of increasing interest with respect to radiosensitization. The physical mechanisms of dose enhancement from X-rays interacting with nanoparticles has been well described theoretically, however have been insufficient in adequately explaining radiobiological response. Further confounding experimental observations is examples of radioprotection. Consequently, other mechanisms have gained increasing attention, especially via enhanced production of reactive oxygen species (ROS) leading to chemical-based mechanisms. Despite the large number of variables differing between published studies, a consensus identifies ROS-related mechanisms as being of significant importance. Understanding the structure-function relationship in enhancing ROS generation will guide optimization of metal nanoparticle radiosensitisers with respect to maximizing oxidative damage to cancer cells. This review highlights the physico-chemical mechanisms involved in enhancing ROS, commonly used assays and experimental considerations, variables involved in enhancing ROS generation and damage to cells and identifies current gaps in the literature that deserve attention. ROS generation and the radiobiological effects are shown to be highly complex with respect to nanoparticle physico-chemical properties and their fate within cells. There are a number of potential biological targets impacted by enhancing, or scavenging, ROS which add significant complexity to directly linking specific nanoparticle properties to a macroscale radiobiological result.

Light-triggered crosslinking of gold nanoparticles for remarkably improved radiation therapy and computed tomography imaging of tumors

Aim: We aimed to characterize the tumor-targeting and radiosensitization properties of the photo-responsive gold nanoparticles (AuNPs) decorated photolabile diazirine group and folic acid for improved radiotherapy and computed tomography imaging of tumors. Methods: Folic acid and photolabile diazirine group were covalently conjugated on the surface of AuNPs to afford the desired photo-responsive dAuNP-FA (AuNPs capped with poly(ethylene) glycol ligands bearing photolabile diazirine group and folic acid). The probes were intravenously injected into tumor-bearing mice followed by photocrosslinking upon 405 nm laser irradiation for radiotherapy and computed tomography imaging of tumors in vivo. Results: Light-triggered crosslinking of AuNPs in vivo remarkably enhanced the accumulation and retention of AuNPs within tumors. Conclusion: We have successfully developed a novel photo-responsive Au particle-based tumor theranostic probe showing remarkably improved tumor targeting ability and radiosensitization effect.

Bifunctional Au-Fe3O4 Nanoheterodimers Acting as X-ray Protector in Healthy Cells and as X-ray Enhancer in Tumor Cells

Bifunctional Au-Fe₃O₄ nanoheterodimers were synthesized by thermally decomposing Fe(III)oleate on gold nanoparticles followed by functionalizing with tiron, 2,3-dihydroxybenzoic acid, or caffeic acid. These catechol derivatives are antioxidative and thus are predicted to function as superoxide scavengers. In particular, caffeic acid lost its antioxidant capacity, although it was covalently linked through its carboxyl moiety to the Fe₃O₄ surface. Tiron was shown to bind via its catechol group to the Au-Fe₃O₄ nanoheterodimers, and 2,3-dihydroxybenzoic was just physisorbed between the oleic acid surface structures. Caffeic-acid stabilized Au-Fe₃O₄ nanoheterodimers turned out to act as X-ray protector in healthy cells but as X-ray enhancing agents in cancer cells. Furthermore, these functionalized Au-Fe₃O₄ nanoheterodimers were found to inhibit the migratory capacity of the cancer cells.

Radiosensitive core/satellite ternary heteronanostructure for multimodal imaging-guided synergistic cancer radiotherapy

Developing safe, effective and targeting radiosensitizers with clear action mechanisms to achieve synergistic localized cancer treatment is an important strategy for radiotherapy. Herein, we design and synthesize a ternary heteronanostructure radiosensitizer (SeAuFe-EpC) with core/satellite morphology by a simple method to realize multimodal imaging-guided cancer radiotherapy. The mechanistic studies reveal that Se incorporation could drastically improve the electrical conductivity and lower the energy barrier between the three components, resulting in more electrons transfer between Se-Au interface and migration over the heterogeneous junction of Au-Fe₃O₄ NPs interface. This synergistic interaction enhanced the energy transfer and facilitated more excited excitons generated by SeAuFe-EpC NPs, thus promoting the transformation of ³O₂ to ¹O₂via resonance energy transfer, finally resulting in irreversible cancer cell apoptosis. Additionally, based on the X-ray attenuation ability and high NIR absorption of AuNPs and the superparamagnetism of Fe₃O₄, in vivo computer tomography, photoacoustic and magnetic resonance tri-modal imaging have been employed to visualize the tracking and targeting ability of the NPs. As expected, the NPs specifically accumulated in orthotopic breast tumor area and achieved synergistic anticancer efficacy, but showed no toxic side effects on main organs. Collectively, this study sheds light on the potential roles of core/satellite heteronanostructure in imaging-guided cancer radiotherapy.

Radio-enhancement effects by radiolabeled nanoparticles

In cancer radiation therapy, dose enhancement by nanoparticles has to date been investigated only for external beam radiotherapy (EBRT). Here, we report on an in silico study of nanoparticle-enhanced radiation damage in the context of internal radionuclide therapy. We demonstrate the proof-of-principle that clinically relevant radiotherapeutic isotopes (i.e. 213Bi, 223Ra, 90Y, 177Lu, 67Cu, 64Cu and 89Zr) labeled to clinically relevant superparamagnetic iron oxide nanoparticles results in enhanced radiation damage effects localized to sub-micron scales. We find that radiation dose can be enhanced by up to 20%, vastly outperforming nanoparticle dose enhancement in conventional EBRT. Our results demonstrate that in addition to the favorable spectral characteristics of the isotopes and their proximity to the nanoparticles, clustering of the nanoparticles results in a nonlinear collective effect that amplifies nanoscale radiation damage effects by electron-mediated inter-nanoparticle interactions. In this way, optimal radio-enhancement is achieved when the inter-nanoparticle distance is less than the mean range of the secondary electrons. For the radioisotopes studied here, this corresponds to inter-nanoparticle distances <50 nm, with the strongest effects within 20 nm. The results of this study suggest that radiolabeled nanoparticles offer a novel and potentially highly effective platform for developing next-generation theranostic strategies for cancer medicine.

Smart Hybrid Nanocomposite for Photodynamic Inactivation of Cancer Cells with Selectivity

Photodynamic therapy has been efficiently applied for cancer therapy. Here, we have fabricated the folic acid (FA)- and pheophorbide A (PA)-conjugated FA/PA@Fe₃O₄ nanoparticle (smart hybrid nanocomposite, SHN) to enhance the photodynamic inactivation (PDI) of specific cancer cells. SHN coated with the PDI agent is designed to have selectivity for the folate receptor (FR) expressed on cancer cells. Structural characteristics and morphology of the fabricated MNPs were studied with X-ray diffraction and scanning electron microscopy. The photophysical properties of SHN were investigated with absorption, emission spectroscopies, and Fourier transform infrared spectroscopy. In addition, the magnetic property of Fe₃O₄ nanoparticle (MNP) can be utilized for the collection of SHNs by an external magnetic field. The photofunctionality was given by the photosensitizer, PA, which generates reactive oxygen species by irradiation of visible light. Generation of singlet oxygen was directly evaluated with time-resolved phosphorescence spectroscopy. Biocompatibility and cellular interaction of SHN were also analyzed by using various cancer cells, such as KB, HeLa, and MCF-7 cells which express different levels of FR on the surface. Cellular adsorption and the PDI effect of SHN on the various cancer cells in vitro were correlated well with the surface expression levels of FR, suggesting potential applicability of SHN on specific targeting and PDI of FR-positive cancers.

Impact of Locally Administered Carboxydextran-Coated Super-Paramagnetic Iron Nanoparticles on Cellular Immune Function

Interstitially administered iron oxide particles are currently used for interoperative localization of sentinel lymph nodes (LNs) in cancer staging. Several studies have described concerns regarding the cellular accumulation of iron oxide nanoparticles relating them to phenotype and function deregulation of macrophages, impairing their ability to mount an appropriate immune response once an insult is present. This study aims to address what phenotypic and functional changes occur during lymphatic transit and accumulation of these particles. Data show that 60 nm carboxydextran-coated iron nanoparticles use a noncellular mechanism to reach the draining LNs and that their accumulation in macrophages induces transient phenotypic and functional changes. Nevertheless, macrophages recover their baseline levels of response within 7 days, and are still able to mount an appropriate response to bacterially induced inflammation.

Copper Oxide Nanoparticles Induce Enhanced Radiosensitizing Effect via Destructive Autophagy

Emerging nanotechnologies for radiotherapy are attracting increasing interest from researchers in recent years. To improve the radiotherapeutic performance, developing nanoparticles that can efficiently generate toxic reactive oxygen species (ROS) under X-ray irradiation are highly desirable. Here, we investigate the potential of copper oxide nanoparticles (CuO NPs) as nanoradiosensitizers. Increased cancer cell inhibition is observed in colony formation assay and real-time cell analysis after the combined treatment with CuO NPs and X-ray irradiation, whereas the CuO NPs alone do not have any negative influence on cell viability, indicating the radiosensitization effect of CuO NPs. Importantly, the significantly increased ROS level in cells contributes to the enhanced damage to cancer cells under the combined treatment. Besides, the cell cycle is regulated to the X-ray-sensitive phase (G₂/M phase) by CuO NPs, which may also account for the inhibited proliferation of cancer cells. Furthermore, results from Western blot analysis and colony formation assay reveal that the increased cell death may be mainly attributed to the excessive autophagy induced by both CuO NPs and X-ray irradiation. Moreover, in vivo experiments verify the radiosensitization of CuO NPs and their favorable biosafety. The current study suggests that CuO NPs can be utilized as nanoradiosensitizers for increasing the efficiency of cancer radiotherapy.

Functionalized Superparamagnetic Iron Oxide Nanoparticles (SPIONs) as Platform for the Targeted Multimodal Tumor Therapy

Standard cancer treatments involve surgery, radiotherapy, chemotherapy, and immunotherapy. In clinical practice, the respective drugs are applied orally or intravenously leading to their systemic circulation in the whole organism. For chemotherapeutics or immune modulatory agents, severe side effects such as immune depression or autoimmunity can occur. At the same time the intratumoral drug doses are often too low for effective cancer therapy. Since monotherapies frequently cannot cure cancer, due to their synergistic effects multimodal therapy concepts are applied to enhance treatment efficacy. The targeted delivery of drugs to the tumor by employment of functionalized nanoparticles might be a promising solution to overcome these challenges. For multimodal therapy concepts and individualized patient care nanoparticle platforms can be functionalized with compounds from various therapeutic classes (e.g. radiosensitizers, phototoxic drugs, chemotherapeutics, immune modulators). Superparamagnetic iron oxide nanoparticles (SPIONs) as drug transporters can add further functionalities, such as guidance or heating by external magnetic fields (Magnetic Drug Targeting or Magnetic Hyperthermia), and imaging-controlled therapy (Magnetic Resonance Imaging).

Sequentially Triggered Delivery System of Black Phosphorus Quantum Dots with Surface Charge-Switching Ability for Precise Tumor Radiosensitization

Cancer radiotherapy suffers from drawbacks such as radiation resistance of hypoxic cells, excessive radiation that causes damage of adjacent healthy tissues, and concomitant side effects. Hence, radiotherapy sensitizers with improved radiotherapeutic performance and requiring a relatively small radiation dose are highly desirable. In this study, a nanosystem based on poly(lactic- co-glycolic acid) (PLGA) and ultrasmall black phosphorus quantum dots (BPQDs) is designed and prepared to accomplish precise tumor radiosensitization. The PLGA nanoparticles act as carriers to package the BPQDs to avoid off-target release and rapid degradation during blood circulation. The nanosystem that targets the polypeptide peptide motif Arg-Gly-Asp-Gys actively accumulates in tumor tissues. The 2,3-dimethylmaleic anhydride shell decomposes in an acidic microenvironment, and the nanoparticles become positively charged, thereby favoring cellular uptake. Furthermore, glutathione (GSH) deoxidizes the disulfide bond of cystamine and sequentially triggers release of BPQDs, rendering tumor cells sensitive to radiotherapy. The treatment utilizing the PLGA_-SS-D@BPQDs nanosystem and X-ray induces cell apoptosis triggered by overproduction of reactive oxygen species. In the in vivo study, the nanosystem shows excellent radiotherapy sensitization efficiency but negligible histological damage of the major organs. This study provides insights into the design and fabrication of surface-charge-switching and pH-responsive nanosystems as potent radiosensitizers to achieve excellent radiotherapy sensitization efficacy and negligible toxic side effects.

A Facile One-Pot Synthesis of Water-Soluble, Patchy Fe3O4-Au Nanoparticles for Application in Radiation Therapy

A facile one-pot synthesis route for the preparation of water-soluble, biocompatible patchy Fe3O4-Au nanoparticles (Fe3O4-Au pNPs) was developed. Biocompatibility was attained through surface functionalization with 1-methyl-3-(dodecylphosphonic acid) imidazolium bromide. The morphology, composition, crystal structure and magnetic properties of the Fe3O4-Au pNPs were investigated by conducting experiments with transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and superconducting quantum interference device, respectively. Internalization of the Fe3O4-Au pNPs by MCF-7 cells occurred via endocytosis. The performance of the Fe3O4-Au pNPs as X-ray radiosensitizer in tumor cells was compared with that of gold nanocluster and Fe3O4 NPs. For this reason, MCF-7, A549 and MCF-10A cells were loaded with the respective kind of nanoparticles and treated with X-rays at doses of 1, 2 or 3 Gy. The nanoparticle-induced changes of the concentration of the reactive oxygen species (ROS) were detected using specific assays, and the cell survival under X-ray exposure was assessed employing the clonogenic assay. In comparison with the gold nanocluster and Fe3O4 NPs, the Fe3O4-Au pNPs exhibited the highest catalytic capacity for ROS generation in MCF-7 and A549 cells, whereas in the X-ray-induced ROS formation in healthy MCF-10A cells was hardly enhanced by the Fe3O4 NPs and Fe3O4-Au pNPs. Moreover, the excellent performance of Fe3O4-Au pNPs as X-ray radiosensitizers was verified by the quickly decaying radiation dose survival curve of the nanoparticle-loaded MCF-7 and A549 cells and corroborated by the small values of the associated dose-modifying factors.

Mechanisms of the Antibacterial Effects of TiO2–FeOx under Solar or Visible Light: Schottky Barriers versus Surface Plasmon Resonance

This study reports the significant mechanistic difference between binary-oxide antibacterial films with the same composition but different microstructures. Binary TiO2-FeOx films were found to present a faster bacterial inactivation kinetics under visible light irradiation than each single oxide acting independently. The interaction between the film active surface species and the bacteria within the disinfection period was followed by X-ray photoelectron spectroscopy (XPS) and provided the evidence for a redox catalysis taking place during the bacterial inactivation time. The optical and surface properties of the films were evaluated by appropriate surface analytical methods. A differential mechanism is suggested for each specific microstructure inducing bacterial inactivation. The surface FeOx plasmon resonance transferred electrons into the conduction band of TiO2 because of the Schottky barrier after Fermi level equilibration of the two components. An electric field at the interface between TiO2 and FeOx, favors the separation of the photo-generated charges leading to a faster bacterial inactivation by TiO2–FeOx compared to the bacterial inactivation kinetics by each of the single oxides.