Nanoparticles for Radiation Therapy Enhancement: the Key Parameters

Secondary electron dynamics in core-shell-satellite nanoparticles: a computational strategy for targeted cancer treatment

As the global incidence of cancer escalates, there exists an urgent necessity for innovative therapeutic modalities. While radiation therapy is indispensable in oncology, it faces significant challenges in achieving an optimal equilibrium between tumour ablation and the preservation of surrounding healthy tissues. Noteworthy advancements such as intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D-CRT) have enhanced the precision of treatment; however, their efficacy is still constrained by the accuracy of tumour delineation. The utilization of radiosensitizers, with a particular emphasis on metal nanoparticles, presents a promising avenue for augmenting the susceptibility of neoplastic cells to ionizing radiation. This research examines the potential of core-shell-satellite Fe3O4-SiO2-Au nanoparticles as effective radiosensitizers. By investigating the interaction of individual nanoparticles situated within a water phantom of 20 micrometers in diameter with monochromatic photon beams at energies of 50, 100, and 150 keV, we analyse how variations in the structural composition of Au nanoparticles and their concentrations within these multifaceted nanoparticles influence the efficacy of radiation therapy, employing Monte Carlo simulations corroborated by the general-purpose radiation transport code PHITS. Our investigation aspires to refine nanoparticle-based methodologies to enhance cancer treatment outcomes, potentially facilitating the development of more targeted therapeutic interventions that minimize adverse effects while improving patient survival rates.

Nanomedicine-Enhanced Radiotherapy for Glioblastoma: Advances in Targeted Therapy and Adaptive Treatment Strategies

Glioblastoma multiforme remains one of the most aggressive and treatment-resistant brain tumors that necessitate innovative therapeutic approaches. Nanomedicine has emerged as a promising strategy to enhance radiation therapy by improving drug delivery, radiosensitization, and real-time treatment monitoring. Stimuli-responsive nanoparticles can overcome limitations of the blood-brain barrier, modulate tumor microenvironment, and facilitate targeted therapeutic interventions. The integration of nanotechnology with proton and X-ray radiotherapy offers improved dose precision, enhanced radiosensitization, and adaptive treatment strategies. Furthermore, Artificial Intelligence-driven nanoparticle designs are optimizing therapeutic outcomes by tailoring formulations to tumor-specific characteristics. While promising, clinical translation remains a challenge that requires rigorous validation to ensure safety and efficacy. This review highlights advancements in nanomedicine-enhanced radiotherapy and future directions for glioblastoma multiforme treatment.

Inorganic Nanomaterials Meet the Immune System: An Intricate Balance

The immune system provides defense against foreign agents that are considered harmful for the organism. Inorganic nanomaterials can be recognized by the immune system as antigens, inducing an immune reaction dependent on the patient's immunological anamnesis and from several factors including size, shape, and the chemical nature of the nanoparticles. Furthermore, nanomaterials-driven immunomodulation might be exploited for therapeutic purposes, opening new horizons in oncology and beyond. In this scenario, we present a critical review of the state of the art regarding the preclinical evaluation of the effects of the most promising metals for biomedical applications (gold, silver, and copper) on the immune system. Because exploiting the interactions between the immune system and inorganic nanomaterials may result in a game changer for the management of (non)communicable diseases, within this review we encounter the need to summarize and organize the plethora of sometimes inconsistent information, analyzing the challenges and providing the expected perspectives. The field is still in its infancy, and our work emphasizes that a deep understanding on the influence of the features of metal nanomaterials on the immune system in both cultured cells and animal models is pivotal for the safe translation of nanotherapeutics to the clinical practice.

An alternate model to describe the radio-potentializing effects of metal-based nanoparticles in radiation therapy

BACKGROUND AND OBJECTIVES

The use of numerical models to predict radiosensitizing properties induced by metal-based nanoparticles (NPs) remains a real challenge in oncology. As most of the interactions due to radiation in biological environments originate from the secondary particles produced, we aim to formalize the relationship between these secondary particles, the irradiation dose and the NP concentration, to optimize mathematical and numerical tools for assessing NP-induced radiosensitization.

METHODS

GATE simulations were carried out to demonstrate a linear and affine relationship between specific radiophysical quantities, the irradiation dose and NP concentration. This research has led to an effective new method for predicting radiophysical events and the proposal of a new model for predicting cell death. This model was confirmed by experimental biological results obtained from a clonogenic assay performed on U251 and U87 glioblastoma cells after exposure to different concentrations of metal-based NPs.

RESULTS

We achieved an efficient method for quantifying certain radiophysical species (number of ionizations, photo- and compton electrons, bremsstrahlung and deposited dose) in the presence of NPs and at different irradiation doses. These findings have enabled us to suggest an extension of the linear quadratic (LQ) cell survival model. The LQ extension model was compared with experimental data both obtained in the laboratory and extracted from the literature.

CONCLUSIONS

Radiophysical events provide valuable information for predicting the radiobiological and radiosensitizing effects of metal-based NPs in the context of X-ray photon irradiation. The extension of the LQ model we developed enables cell death to be predicted for different NP concentrations based on concentration effects alone.

In vitro study of effect of gold nanoparticles conjugated with triptorelin peptide on the radiosensitivity of breast cancer cells (MCF-7)

INTRODUCTION

One of the significant challenges in the field of radiation therapy for cancer cells is the damage to healthy tissues in the vicinity of the tumor. In light of the recent developments in nanotechnology, as well as the historical use of materials with high atomic number to enhance contrast in medical imaging, a potential solution was proposed: the use of targeted gold nanoparticles in conjunction with the triptorelin peptide to enhance the radiation sensitivity of MCF-7 cancer cells. Consequently, due to the presence of the triptorelin peptide receptor on the surface of MCF-7 cells, the nanoparticles are absorbed by the target cells in a targeted manner. By increasing the interaction between the nanoparticles and X-ray MeV 6, it was anticipated that there will be an increase in cell death and optimization of the treatment quality.

METHODOLOGY

Following synthesis and combination with triptorelin peptide, gold nanoparticles coated with alginate were subjected to characterization tests. Subsequently, MTT and colony tests were conducted to ascertain the toxicity of the nanoparticles and the optimal dosage of the drug for use on MCF-7 cells. Subsequently, the cells were subjected to the colony assay to ascertain the level of radiation sensitivity. Following the culturing and treatment of the cells with a concentration of 20 μg/ml of nanoparticles, they were subjected to 2, 4, 6, and 8 Gy (Gray) of radiation. Following the incubation period, the resulting colonies were stained and counted. Finally, the flow cytometry test was employed by Annexin V PI kit to determine the extent of cell death caused by apoptosis.

RESULTS

The toxicity test finally indicated that a concentration of 20 μg/ml should be employed in the continuation of the study. The results of the colony assay, which was conducted to determine radiation sensitivity, revealed a dose enhancement factor (DEF) of 1.68, 2.32, 1.76 and 1.86, respectively, for radiation doses of 2, 4, 6 and 8 Gy. These findings were observed in the group that received the targeted nanoparticle in conjunction with radiation therapy, when compared to the group that received only radiation therapy. Additionally, the flow cytometry test yielded a synergistic effect of 5.63. The administration of gold nanoparticles in both forms was observed to result in a reduction in cell survival. However, the radio-sensitizing effect of targeted gold nanoparticles with triptorelin peptide was greater, which can be attributed to enhanced cellular uptake by breast cancer cells (MCF-7). Au-Triptorelin nanoparticles with their specific targeting increased radiosensitivity and increased apoptosis compared to the group that only received radiation.

CONCLUSION

The results of the tests showed that Triptorelin-AuNPs nanoparticles have the ability to cause targeted sensitivity in MCF-7 cells with triptorelin peptide receptors.

An Evaluation of the Potential Radiosensitization Effect of Spherical Gold Nanoparticles to Induce Cellular Damage Using Different Radiation Qualities

Global disparities in cancer prevention, detection, and treatment demand a unified international effort to reduce the disease's burden and improve outcomes. Despite advances in chemotherapy and radiotherapy, many tumors remain resistant to these treatments. Gold nanoparticles (AuNPs) have shown promise as radiosensitizers, enhancing the effectiveness of low-energy X-rays by emitting Auger electrons that cause localized cellular damage. In this study, spherical AuNPs of 5 nm and 10 nm were characterized and tested on various cell lines, including malignant breast cells (MCF-7), non-malignant cells (CHO-K1 and MCF-10A), and human lymphocytes. Cells were treated with AuNPs and irradiated with attenuated 6 megavoltage (MV) X-rays or p(66)/Be neutron radiation to assess DNA double-strand break (DSB) damage, cell viability, and cell cycle progression. The combination of AuNPs and neutron radiation induced higher levels of γ-H2AX foci and micronucleus formation compared to treatments with AuNPs or X-ray radiation alone. AuNPs alone reduced cellular kinetics and increased the accumulation of cells in the G2/M phase, suggesting a block of cell cycle progression. For cell proliferation, significant effects were only observed at the concentration of 50 μg/mL of AuNPs, while lower concentrations had no inhibitory effect. Further research is needed to quantify internalized AuNPs and correlate their concentration with the observed cellular effects to unravel the biological mechanisms of their radioenhancement.

Breakthroughs in nanoparticle-based strategies for pancreatic cancer therapy

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers worldwide, mainly due to its high heterogeneity, resistance to therapy and late diagnosis, with a 5-year survival rate of less than 10%. This dismal prognosis has promoted strategies to develop more effective treatments. Nanoparticle-based strategies have emerged, in the last decades, as a great opportunity because they can enhance drug delivery and promote controlled release, presenting lower side effects than conventional therapeutic regimens. Moreover, nanoparticles can often be modified to target specific cells or to achieve a sustained release of the drugs into the tumor. However, very few nanoparticle-based therapies are clinically approved. Concretely for pancreatic cancer treatment only two nanoformulations have been approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) so far. Clinical translation of nanoparticles remains a challenge for modern medicine, and in particular for pancreatic cancer therapy, because of the complexity of the disease, and a lack of studies been performed in clinically relevant in vitro and in vivo models. In this review, we have summarized the most recent clinical trials using nanoparticle-based formulations in PDAC, giving a small context of the diverse types of nanoparticles employed and the most recent advancements in the field.

Revolutionizing radiotherapy: gold nanoparticles with polyphenol coating as novel enhancers in breast cancer cells-an in vitro study

Breast cancer is the most common cancer among women, with over 1 million new cases and around 400,000 deaths annually worldwide. This makes it a significant and costly global health challenge. Standard treatments like chemotherapy and radiotherapy, often used after mastectomy, show varying effectiveness based on the cancer subtype. Combining these treatments can improve outcomes, though radiotherapy faces limitations such as radiation resistance and low selectivity for malignant cells. Nanotechnologies, especially metallic nanoparticles (NPs), hold promise for enhancing radiotherapy. Gold nanoparticles (AuNPs) are particularly notable due to their high atomic number, which enhances radiation damage through the photoelectric effect. Studies shown that AuNPs can act as effective radiosensitizers, improving tumor damage during radiotherapy increasing the local radiation dose delivered. Traditional AuNPs synthesis methods involve harmful chemicals and extreme conditions, posing health risks. Green synthesis methods using plant extracts offer a safer and more environmentally friendly alternative. This study investigates the synthesis of AuNPs using Laurus nobilis leaf extract and their potential as radiosensitizers in breast carcinoma cell lines (MCF-7). These cells were exposed to varying doses of X-ray irradiation, and the study assessed cell viability, morphological changes and DNA damage. The results showed that green-synthesized AuNPs significantly enhanced the therapeutic effects of radiotherapy at lower radiation doses, indicating their potential as a valuable addition to breast cancer treatment.

Enhancing Chordoma Radiotherapy: Ta@PVP Nanoparticles as Potent Radiosensitizers

Surgical resection and high-dose radiotherapy constitute the standard therapeutic approaches for chordoma. However, the efficacy of radiotherapy is often compromised by the tumor microenvironment's hypoxic conditions, which confer radiation resistance, and by the potential damage to adjacent spinal cord and neural structures from elevated radiation doses. To address these challenges, we employed high biocompatible poly(vinylpyrrolidone)-modified tantalum nanoparticles (Ta@PVP NPs) as a potent radiosensitizer to augment the radiotherapy sensitivity of chordoma. Upon exposure to X-ray irradiation, Ta@PVP NPs demonstrated the capability to efficiently deposit X-ray radiation energy within the tumor microenvironment, subsequently generating reactive oxygen species (ROS) that induce oxidative stress in the tumor. Both in vitro and in vivo experiments revealed that Ta@PVP NPs significantly enhanced the cytotoxic effects of X-ray, thereby markedly inhibiting the proliferation of chordoma cells and impeding tumor growth. This study explored the radiosensitization potential of Ta@PVP NPs in the context of chordoma, highlighting the application of radiosensitizers as a promising strategy to augment the efficacy of chordoma radiotherapy.

Modeling synergy and individual effects of X-ray induced photodynamic therapy components

X-ray induced photodynamic therapy (XPDT) utilizes self-lighting nanoparticles to combine the benefits of radiotherapy and photodynamic therapy. These nanomaterials transform X-ray to visible light that can be absorbed by nearby photosensitizers and in the presence of surrounding oxygen molecules generates reactive oxygen species, which are very toxic to the cells. Despite many studies conducted on modelling XPDT, little focused on the contribution of each component as well as their synergy effects. We developed a multiscale physicochemical model of XPDT to incorporate the key role of molecular oxygen in PDT component efficiency. Simultaneously, the effects of RT in the presence of TiO2 nanoscintillators evaluated experimentally on HT-29 cell line. Simulation results predicted necrosis and apoptosis death of cancerous cells and estimated the minimum XPDT efficiency under specific conditions. The calculated synergism index estimated a synergism ratio greater than one indicated that tumor growth inhibition in XPDT is greater than the sum of each treatment component alone.

Microbeam Radiation Therapy Bio-Dosimetry Enhanced by Novel Radiosensitiser Combinations in the Treatment of Brain Cancer

Background/Objectives: Brain cancer is notoriously resistant to traditional treatments, including radiotherapy. Microbeam radiation therapy (MRT), arrays of ultra-fast synchrotron X-ray beams tens of micrometres wide (called peaks) and spaced hundreds of micrometres apart (valleys), is an effective alternative to conventional treatments. MRT's advantage is that normal tissues can be spared from harm whilst maintaining tumour control. Combining MRT with targeted radiosensitisers, such as nanoparticles, chemotherapeutic drugs, and halogenated pyrimidine drugs, can further improve radiotherapy by enhancing radiation damage. However, the underlying mechanisms of MRT are still being understood, which is essential to ensuring the reliable and successful use of MRT. Methods: An in vitro study was performed using γH2AX imaging, and quantification was performed via confocal microscopy and a clonogenic cell survival assay. Results: We show that methotrexate chemotherapeutics and iododeoxyuridine enhance MRT cell-killing and thulium oxide nanoparticles (TmNPs) broaden MRT peaks, and using γH2AX immunofluorescent confocal microscopy to quantify DNA damage, we further our knowledge of MRT mechanisms. γH2AX images verify the biological responses of cells aligning with the physical collimation of MRT, and we can accurately measure MRT microbeam characteristics bio-dosimetrically. The peak-to-valley dose ratio (PVDR), the ratio of the peak dose to the valley dose that characterises an MRT field, was accurately measured biologically using γH2AX imaging, despite studies previously finding this challenging. Conclusions: The measurement of biological PVDR has been performed for the first time with high-Z radiosensitisers, including nanoparticles, and several novel radiosensitiser-enhanced MRT mechanisms were discovered. Our results deepen our understanding of MRT with radiosensitisers, and can contribute to its accurate and future successful use in treating cancer.

Emerging nitric oxide gas-assisted cancer photothermal treatment

Photothermal therapy (PTT) has garnered significant attention in recent years, but the standalone application of PTT still faces limitations that hinder its ability to achieve optimal therapeutic outcomes. Nitric oxide (NO), being one of the most extensively studied gaseous molecules, presents itself as a promising complementary candidate for PTT. In response, various nanosystems have been developed to enable the simultaneous utilization of PTT and NO-mediated gas therapy (GT), with the integration of photothermal agents (PTAs) and thermally-sensitive NO donors being the prevailing approach. This combination seeks to leverage the synergistic effects of PTT and GT while mitigating the potential risks associated with gas toxicity through the use of a single laser irradiation. Furthermore, additional internal or external stimuli have been employed to trigger NO release when combined with different types of PTAs, thereby further enhancing therapeutic efficacy. This comprehensive review aims to summarize recent advancements in NO gas-assisted cancer photothermal treatment. It commences by providing an overview of various types of NO donors and precursors, including those sensitive to photothermal, light, ultrasound, reactive oxygen species, and glutathione. These NO donors and precursors are discussed in the context of dual-modal PTT/GT. Subsequently, the incorporation of other treatment modalities such as chemotherapy (CHT), photodynamic therapy (PDT), alkyl radical therapy, radiation therapy, and immunotherapy (IT) in the creation of triple-modal therapeutic nanoplatforms is presented. The review further explores tetra-modal therapies, such as PTT/GT/CHT/PDT, PTT/GT/CHT/chemodynamic therapy (CDT), PTT/GT/PDT/IT, PTT/GT/starvation therapy (ST)/IT, PTT/GT/Ca2+ overload/IT, PTT/GT/ferroptosis (FT)/IT, and PTT/GT/CDT/IT. Finally, potential challenges and future perspectives concerning these novel paradigms are discussed. This comprehensive review is anticipated to serve as a valuable resource for future studies focused on the development of innovative photothermal/NO-based cancer nanotheranostics.

A novel approach to double-strand DNA break analysis through γ-H2AX confocal image quantification and bio-dosimetry

DNA damage occurs in all living cells. γ-H2AX imaging by fluorescent microscopy is widely used across disciplines in the analysis of double-strand break (DSB) DNA damage. Here we demonstrate a method for the quantitative analysis of such DBSs. Ionising radiation, well known to induce DSBs, is used in this demonstration, and additional DBSs are induced if high-Z nanoparticles are present during irradiation. As a deliberate test of the methodology, cells are exposed to a spatially fractionated ionising radiation field, characterised by regions of high and low absorbed radiation dose that are only ever qualitatively verified biologically via γ-H2AX imaging. Here we validate our bio-dosimetric quantification method using γ-H2AX assays in the assessment of DSB enhancement. Our method reliably quantifies DSB enhancement in cells when exposed to either a spatially contiguous or fractionated irradiation fields. Using the γ-H2AX assay, we deduce the biological dose response, and for the first time, demonstrate equivalence to the independently measured physical absorbed dose. Using our novel method, we are also able quantify the nanoparticle DSB enhancement at the cellular level, which is not possible using physical dose measurement techniques. Our method therefore provides a new paradigm in γ-H2AX image quantification of DSBs, as well as an independently validated bio-dosimetry technique.

Enhancing Proton Therapy Efficacy Through Nanoparticle-Mediated Radiosensitization

Proton therapy, characterized by its unique Bragg peak, offers the potential to optimize the destruction of cancer cells while sparing healthy tissues, positioning it as one of the most advanced cancer treatment modalities currently available. However, in comparison to heavy ions, protons exhibit a relatively lower relative biological effectiveness (RBE), which limits the efficacy of proton therapy. The incorporation of nanoparticles for radiosensitization presents a novel approach to enhance the RBE of protons. This review provides a comprehensive discussion of the recent advancements in augmenting the biological effects of proton therapy through the use of nanoparticles. It examines the various types of nanoparticles that have been the focus of extensive research, elucidates their mechanisms of radiation sensitization, and evaluates the factors influencing the efficiency of this sensitization process. Furthermore, this review discusses the latest synergistic therapeutic strategies that integrate nanoparticle-mediated radiosensitization and outlines prospective directions for the future application of nanoparticles in conjunction with proton therapy.

Laser-synthesized plasmonic HfN-based nanoparticles as a novel multifunctional agent for photothermal therapy

Hafnium nitride nanoparticles (HfN NPs) can offer appealing plasmonic properties at the nanoscale, but the fabrication of stable water-dispersible solutions of non-toxic HfN NPs exhibiting plasmonic features in the window of relative biological transparency presents a great challenge. Here, we demonstrate a solution to this problem by employing ultrashort (femtosecond) laser ablation from a HfN target in organic solutions, followed by a coating of the formed NPs with polyethylene glycol (PEG) and subsequent dispersion in water. We show that the fabricated NPs exhibit plasmonic absorption bands with maxima around 590 nm, 620 nm, and 650 nm, depending on the synthesis environment (ethanol, acetone, and acetonitrile, respectively), which are largely red-shifted compared to what is expected from pure HfN NPs. The observed shift is explained by including nitrogen-deficient hafnium nitride and hafnium oxynitride phases inside the core and oxynitride coating of NPs, as follows from a series of structural characterization studies. We then show that the NPs can provide a strong photothermal effect under 808 nm excitation with a photothermal conversion coefficient of about 62%, which is comparable to the best values reported for plasmonic NPs. MTT and clonogenic assays evidenced very low cytotoxicity of PEG-coated HfN NPs to cancer cells from different tissues up to 100 μg mL-1 concentrations. We finally report a strong photothermal therapeutic effect of HfN NPs, as shown by 100% cell death under 808 nm light irradiation at NP concentrations lower than 25 μg mL-1. Combined with additional X-ray theranostic functionalities (CT scan and photon capture therapy) profiting from the high atomic number (Z = 72) of Hf, plasmonic HfN NPs promise the development of synergetically enhanced modalities for cancer treatment.

Oxidative stress-modifying effects of TiO2nanoparticles with varying content of Ti3+(Ti2+) ions

Nanoparticles (NPs) with reactive oxygen species (ROS)-regulating ability have recently attracted great attention as promising agents for nanomedicine. In the present study, we have analyzed the effects of TiO2defect structure related to the presence of stoichiometric (Ti4+) and non-stoichiometric (Ti3+and Ti2+) titanium ions in the crystal lattice and TiO2NPs aggregation ability on H2O2- and tert-butyl hydroperoxide (tBOOH)-induced ROS production in L929 cells. Synthesized TiO2-A, TiO2-B, and TiO2-C NPs with varying Ti3+(Ti2+) content were characterized by x-ray powder diffraction, transmission electron microscopy, small-angle x-ray scattering, x-ray photoelectron spectroscopy, and optical spectroscopy methods. Given the role of ROS-mediated toxicity for metal oxide NPs, L929 cell viability and changes in the intracellular ROS levels in H2O2- and tBOOH-treated L929 cells incubated with TiO2NPs have been evaluated. Our research shows that both the amount of non-stoichiometric Ti3+and Ti2+ions in the crystal lattice of TiO2NPs and NPs aggregative behavior affect their catalytic activity, in particular, H2O2decomposition and, consequently, the efficiency of aggravating H2O2- and tBOOH-induced oxidative damage to L929 cells. TiO2-A NPs reveal the strongest H2O2decomposition activity aligning with their less pronounced additional effects on H2O2-treated L929 cells due to the highest amount of Ti3+(Ti2+) ions. TiO2-C NPs with smaller amounts of Ti3+ions and a tendency to aggregate in water solutions show lower antioxidant activity and, consequently, some elevation of the level of ROS in H2O2/tBOOH-treated L929 cells. Our findings suggest that synthesized TiO2NPs capable of enhancing ROS generation at concentrations non-toxic for normal cells, which should be further investigated to assess their possible application in nanomedicine as ROS-regulating pharmaceutical agents.

Shell-by-Shell functionalized nanoparticles as radiosensitizers and radioprotectors in radiation therapy of cancer cells and tumor spheroids

Shell-by-Shell (SbS)-functionalized NPs can be tailor-made by combining a metal oxide NP core of choice with any desired phosphonic acids and amphiphiles as 1st or 2nd ligand shell building blocks. The complementary composition of such highly hierarchical structures makes them interesting candidates for various biomedical applications, as certain active ingredients can be incorporated into the structure. Here, we used TiO2 and CoFe2O4 NPs as drug delivery tools and coated them with a hexadecylphosphonic acid and with hexadecyl ammonium phenolates (caffeate, p-coumarate, ferulate), that possess anticancer as well as antioxidant properties. These architectures were then incubated in 2D and 3D cell cultures of non-tumorigenic and tumorigenic breast cells and irradiated to study their anticancer effect. It was found that both, the functionalized TiO2 and CoFe2O4 NPs acted as strong protective agents in non-tumorigenic spheroids. In contrast, the functionalized CoFe2O4 NPs induce a higher damage in irradiated tumor spheroids compared to the functionalized TiO2 NPs. CoFe3O4 NPs act additionally as radiosensitizing agents to the tumor spheroids. The radio-enhancement of the CoFe2O4 NPs is due to the generation of highly toxic hydroxyl radicals during X-ray irradiation. The irradiation exposed the CoFe2O4 surface, releasing the anticancer drugs into the cytoplasm and making the surface Co2+ ions accessible. These surface ions catalyze the Fenton reaction. This combination of radiosensitizer and anticancer drug delivery proved to be a very effective nanotherapeutic in 2D and 3D cell cultures of breast cancer cells.

Quantitative Single-Cell Comparison of Sensitization to Radiation and a Radiomimetic Drug for Diverse Gold Nanoparticle Coatings

Metal-based nanoparticles (NPs) have entered clinical use for enhancing radiotherapy, but the underlying mechanisms remain ambiguous. Herein, single-cell analysis of two cell lines in response to megavolt irradiation and a radiomimetic drug, neocarzinostatin (NCS) after coculture with gold NPs with different surface coatings, polyethylene glycol (AuPEG), PEG, and transferrin (AuT) or silica (AuSiO2), is reported. Different surface chemistry presents a major challenge for objective comparison between the biological impacts where major differences in cell-uptake exist. AuSiO2 NPs are the most efficient for promoting radiosensitization despite being associated with cells 10 times less than the actively targeted AuT NPs. Conversely, for cells exposed to NCS, AuSiO2 NPs impede the radiomimetic action and promote cell survival. AuT NPs enhance death of cells in combination with NCS showing that NPs can sensitize against cytotoxic agents in addition to radiation. While NPs contribute to radiosensitization (or enhancing/impeding chemotherapeutic drug activity), due to cell and cell line heterogeneity, the ultimate radiosensitivity of a cell appears to be dominated by its inherent radiosensitivity and how this cell-regulated response is manipulated by NPs. This is evidenced through comparison of radiobiological response of cells with equivalent NP association rather than equivalent coculture conditions.

Innovative 3D printing and molding process for secondary-skin-collimator fabrication

Purpose. Secondary skin collimation (SSC) is essential for shielding normal tissues near tumors during electron and orthovoltage radiation treatments. Traditional SSC fabrication methods, such as crafting in-house lead sheets, are labor-intensive and produce SSCs with low geometric accuracy. This study introduces a workflow that integrated 3D scanning and 3D printing technologies with an in-house mold process, enabling the production of patient-specific SSCs within six hours.Methods. An anthropomorphic head phantom was scanned with a handheld 3D scanner. The resulting scan data was imported into 3D modeling software for design. The completed model was exported to a 3D printer as a printable file. Subsequently, molten Cerrobend was poured into the mold and allowed to set, completing the SSC production. Geometric accuracy was assessed using CT images, and the shielding effectiveness was evaluated through film dosimetry.Results. The 3D printed mold achieved submillimeter accuracy (0.5 mm) and exhibited high conformity to the phantom surface. It successfully endured the weight and heat of the Cerrobend during pouring and curing. Dosimetric analysis conducted with radiochromic film demonstrated good agreement between the measured and expected attenuation values of the SSC slab, within ±3%.Conclusions. This study presents a proof of concept for novel mold room workflows that produce patient-specific SSCs within six hours, a significant improvement over the traditional SSC fabrication process, which takes 2-3 days. The submillimeter accuracy and versatility of 3D scanning and printing technologies afford greater design freedom and enhanced delivery accuracy for cases involving irregular geometries.

Ultrathin and Biodegradable Bismuth Oxycarbonate Nanosheets with Massive Oxygen Vacancies for Highly Efficient Tumor Therapy

Nanomaterials doped with high atom number elements can improve the efficacy of cancer radiotherapy, but their clinical application faces obstacles, such as being difficult to degrade in vivo, or still requiring relatively high radiation dose. In this work, a bismuth oxycarbonate-based ultrathin nanosheet with the thickness of 2.8 nm for safe and efficient tumor radiotherapy under low dose of X-ray irradiation is proposed. The high oxygen content (62.5% at%) and selective exposure of the facets of ultrathin 2D nanostrusctures facilitate the escape of large amounts of oxygen atoms on bismuth nanosheets from surface, forming massive oxygen vacancies and generating reactive oxygen species that explode under the action of X-rays. Moreover, the exposure of almost all atoms to environmental factors and the nature of oxycarbonates makes the nanosheets easily degrade into biocompatible species. In vivo studies demonstrate that nanosheets could induce apoptosis in cancer cells after low dose of X-ray irradiation without causing any damage to the liver or kidney. The tumor growth inhibition effect of radiotherapy increases from 49.88% to 90.76% with the help of bismuth oxycarbonate nanosheets. This work offers a promising future for nanosheet-based clinical radiotherapies of malignant cancers.

Enhanced Cytotoxicity against a Pancreatic Cancer Cell Line Combining Radiation and Gold Nanoparticles

The present work consisted of an exploratory study aiming to evaluate in vitro the potential of AuNPs during Radiation Therapy (RT) in human pancreatic adenocarcinoma cells. AuNPs coated with hyaluronic and oleic acids (HAOA-AuNPs) or with bombesin peptides (BBN-AuNPs) were used. AuNPs were characterized by Atomic Force Microscopy (AFM) and Dynamic Light Scattering. BxPC-3 tumor cells were irradiated with a 6 MV X-rays beam, in the absence or presence of AuNPs. AFM showed that HAOA-AuNPs and BBN-AuNPs are spherical with a mean size of 83 ± 20 nm and 49 ± 12 nm, respectively. For RT alone, a reduction in cell viability of up to 33 ± 12% was obtained compared to the control (p ≤ 0.0001). HAOA-AuNPs alone at 200 and 400 μM showed a reduction in cell viability of 20 ± 4% and 35 ± 4%, respectively, while for BBN-AuNPs, at 50 and 200 μM, a reduction in cell viability of 25 ± 3% and 37 ± 3% was obtained, respectively, compared to the control (p < 0.0001). At 72 h post-irradiation, a decrease in cell viability of 26 ± 3% and 22 ± 2% between RT + HAOA-AuNPs at 400 μM and RT + BBN-AuNPs at 50 μM, compared to RT alone, was obtained (p < 0.004). The combination of RT with AuNPs led to a significant decrease in cell viability compared to the control, or RT alone, thus representing an improved effect.

Evaluation of core-shell Fe3O4@Au nanoparticles as radioenhancer in A549 cell lung cancer model

In radiotherapy, metallic nanoparticles are of high interest in the fight against cancer for their radiosensitizing effects. This study aimed to evaluate the ability of core-shell Fe3O4@Au nanoparticles to potentiate the irradiation effects on redox-, pro-inflammatory markers, and cell death of A549 human pulmonary cancer cells. The hybrid Fe3O4@Au nanoparticles were synthesized using green chemistry principles by the sonochemistry method. Their characterization by transmission electron microscopy demonstrated an average size of 8 nm and a homogeneous distribution of gold. The decreased hydrodynamic size of these hybrid nanoparticles compared to magnetite (Fe3O4) nanoparticles showed that gold coating significantly reduced the aggregation of Fe3O4 particles. The internalization and accumulation of the Fe3O4@Au nanoparticles within the cells were demonstrated by Prussian Blue staining. The reactive oxygen species (ROS) levels measured by the fluorescent probe DCFH-DA were up-regulated, as well as mRNA expression of SOD, catalase, GPx antioxidant enzymes, redox-dependent transcription factor Nrf2, and ROS-producing enzymes (Nox2 and Nox4), quantified by RT-qPCR. Furthermore, irradiation coupled with Fe3O4@Au nanoparticles increased the expression of canonical pro-inflammatory cytokines and chemokines (TNF-α, IL-1β, IL-6, CXCL8, and CCL5) assessed by RT-qPCR and ELISA. Hybrid nanoparticles did not potentiate the increased DNA damage detected by immunofluorescence following the irradiation. Nevertheless, Fe3O4@Au caused cellular damage, leading to apoptosis through activation of caspase 3/7, secondary necrosis quantified by LDH release, and cell growth arrest evaluated by clonogenic-like assay. This study demonstrated the potential of Fe3O4@Au nanoparticles to potentiate the radiosensitivity of cancerous cells.

Investigation of Photodynamic Therapy Promoted by Cherenkov Light Activated Photosensitizers-New Aspects and Revelations

This work investigates the proposed enhanced efficacy of photodynamic therapy (PDT) by activating photosensitizers (PSs) with Cherenkov light (CL). The approaches of Yoon et al. to test the effect of CL with external radiation were taken up and refined. The results were used to transfer the applied scheme from external radiation therapy to radionuclide therapy in nuclear medicine. Here, the CL for the activation of the PSs (psoralen and trioxsalen) is generated by the ionizing radiation from rhenium-188 (a high-energy beta-emitter, Re-188). In vitro cell survival studies were performed on FaDu, B16 and 4T1 cells. A characterization of the PSs (absorbance measurement and gel electrophoresis) and the CL produced by Re-188 (luminescence measurement) was performed as well as a comparison of clonogenic assays with and without PSs. The methods of Yoon et al. were reproduced with a beam line at our facility to validate their results. In our studies with different concentrations of PS and considering the negative controls without PS, the statements of Yoon et al. regarding the positive effect of CL could not be confirmed. There are slight differences in survival fractions, but they are not significant when considering the differences in the controls. Gel electrophoresis showed a dominance of trioxsalen over psoralen in conclusion of single and double strand breaks in plasmid DNA, suggesting a superiority of trioxsalen as a PS (when irradiated with UVA). In addition, absorption measurements showed that these PSs do not need to be shielded from ambient light during the experiment. An observational test setup for a PDT nuclear medicine approach was found. The CL spectrum of Re-188 was measured. Fluctuating inconclusive results from clonogenic assays were found.

Carbon-Iodine Polydiacetylene Nanofibers for Image-Guided Radiotherapy and Tumor-Microenvironment-Enhanced Radiosensitization

Radiotherapy is a mainstay treatment used in clinics for locoregional therapy, although it still represents a great challenge to improve the sensitivity and accuracy of radiotherapy for tumors. Here, we report the conjugated polymer, polydiiododiacetylene (PIDA), with an iodine content of 84 wt %, as a highly effective computed tomography (CT) contrast agent and tumor microenvironment-responsive radiosensitizer. PIDA exhibited several key properties that contribute to the improvement of precision radiotherapy. The integrated PIDA nanofibers confined within the tumor envelope demonstrated amplified CT intensity and prolonged retention, providing an accurate calculation of dose distribution and precise radiation delivery for CT image-guided radiotherapy. Therefore, our strategy pioneers PIDA nanofibers as a bridge to cleverly connect a fiducial marker to guide accurate radiotherapy and a radiosensitizer to improve tumor sensitivity, thereby minimizing potential damage to surrounding tissues and facilitating on-demand therapeutic intervention in tumors.

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.

Synthesis and Bioapplication of Emerging Nanomaterials of Hafnium

A significant amount of progress in nanotechnology has been made due to the development of engineered nanoparticles. The use of metallic nanoparticles for various biomedical applications has been extensively investigated. Biomedical research is highly focused on them because of their inert nature, nanoscale structure, and similar size to many biological molecules. The intrinsic characteristics of these particles, including electronic, optical, physicochemical, and surface plasmon resonance, that can be altered by altering their size, shape, environment, aspect ratio, ease of synthesis, and functionalization properties, have led to numerous biomedical applications. Targeted drug delivery, sensing, photothermal and photodynamic therapy, and imaging are some of these. The promising clinical results of NBTXR3, a high-Z radiosensitizing nanomaterial derived from hafnium, have demonstrated translational potential of this metal. This radiosensitization approach leverages the dependence of energy attenuation on atomic number to enhance energy-matter interactions conducive to radiation therapy. High-Z nanoparticle localization in tumor issue differentially increases the effect of ionizing radiation on cancer cells versus nearby healthy ones and mitigates adverse effects by reducing the overall radiation burden. This principle enables material multifunctionality as contrast agents in X-ray-based imaging. The physiochemical properties of hafnium (Z = 72) are particularly advantageous for these applications. A well-placed K-edge absorption energy and high mass attenuation coefficient compared to elements in human tissue across clinical energy ranges leads to significant attenuation. Chemical reactivity allows for variety in nanoparticle synthesis, composition, and functionalization. Nanoparticles such as hafnium oxide exhibit excellent biocompatibility due to physiochemical inertness prior to incidence with ionizing radiation. Additionally, the optical and electronic properties are applicable in biosensing, optical component coatings, and semiconductors. The wide interest has prompted extensive research in design and synthesis to facilitate property fine-tuning. This review summarizes synthetic methods for hafnium-based nanomaterials and applications in therapy, imaging, and biosensing with a mechanistic focus. A discussion and future perspective section highlights clinical progress and elaborates on current challenges. By focusing on factors impacting applicational effectiveness and examining limitations this review aims to support researchers and expedite clinical translation of future hafnium-based nanomedicine.

Nanotechnology-enhanced radiotherapy and the abscopal effect: Current status and challenges of nanomaterial-based radio-immunotherapy

Rare but consistent reports of abscopal remission in patients challenge the notion that radiotherapy (RT) is a local treatment; radiation-induced cancer cell death can trigger activation and recruitment of dendritic cells to the primary tumor site, which subsequently initiates systemic immune responses against metastatic lesions. Although this abscopal effect was initially considered an anomaly, combining RT with immune checkpoint inhibitor therapies has been shown to greatly improve the incidence of abscopal responses via modulation of the immunosuppressive tumor microenvironment. Preclinical studies have demonstrated that nanomaterials can further improve the reliability and potency of the abscopal effect for various different types of cancer by (1) altering the cell death process to be more immunogenic, (2) facilitating the capture and transfer of tumor antigens from the site of cancer cell death to antigen-presenting cells, and (3) co-delivering immune checkpoint inhibitors along with radio-enhancing agents. Several unanswered questions remain concerning the exact mechanisms of action for nanomaterial-enhanced RT and for its combination with immune checkpoint inhibition and other immunostimulatory treatments in clinically relevant settings. The purpose of this article is to summarize key recent developments in this field and also highlight knowledge gaps that exist in this field. An improved mechanistic understanding will be critical for clinical translation of nanomaterials for advanced radio-immunotherapy. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Radioprotective Potency of Nanoceria

Cancer presents a significant medical challenge that requires effective management. Current cancer treatment options, such as chemotherapy, targeted therapy, radiotherapy, and immunotherapy, have limitations in terms of their efficacy and the potential harm they can cause to normal tissues. In response, researchers have been focusing on developing adjuvants that can enhance tumor responses while minimizing damage to healthy tissues. Among the promising options, nanoceria (NC), a type of nanoparticle composed of cerium oxide, has garnered attention for its potential to improve various cancer treatment regimens. Nanoceria has demonstrated its ability to exhibit toxicity towards cancer cells, inhibit invasion, and sensitize cancer cells to both radiation therapy and chemotherapy. The remarkable aspect is that nanoceria show minimal toxicity to normal tissues while protecting against various forms of reactive oxygen species generation. Its capability to enhance the sensitivity of cancer cells to chemotherapy and radiotherapy has also been observed. This paper thoroughly reviews the current literature on nanoceria's applications within different cancer treatment modalities, with a specific focus on radiotherapy. The emphasis is on nanoceria's unique role in enhancing tumor radiosensitization and safeguarding normal tissues from radiation damage.

Nanoparticle-Mediated Radiotherapy: Unraveling Dose Enhancement and Apoptotic Responses in Cancer and Normal Cell Lines

Cervical cancer remains a pressing global health concern, necessitating advanced therapeutic strategies. Radiotherapy, a fundamental treatment modality, has faced challenges such as targeted dose deposition and radiation exposure to healthy tissues, limiting optimal outcomes. To address these hurdles, nanomaterials, specifically gold nanoparticles (AuNPs), have emerged as a promising avenue. This study delves into the realm of cervical cancer radiotherapy through the meticulous exploration of AuNPs' impact. Utilizing ex vivo experiments involving cell lines, this research dissected intricate radiobiological interactions. Detailed scrutiny of cell survival curves, dose enhancement factors (DEFs), and apoptosis in both cancer and normal cervical cells revealed profound insights. The outcomes showcased the substantial enhancement of radiation responses in cancer cells following AuNP treatment, resulting in heightened cell death and apoptotic levels. Significantly, the most pronounced effects were observed 24 h post-irradiation, emphasizing the pivotal role of timing in AuNPs' efficacy. Importantly, AuNPs exhibited targeted precision, selectively impacting cancer cells while preserving normal cells. This study illuminates the potential of AuNPs as potent radiosensitizers in cervical cancer therapy, offering a tailored and efficient approach. Through meticulous ex vivo experimentation, this research expands our comprehension of the complex dynamics between AuNPs and cells, laying the foundation for their optimized clinical utilization.

Nanodiamond Effects on Cancer Cell Radiosensitivity: The Interplay between Their Chemical/Physical Characteristics and the Irradiation Energy

Nanoparticles are being increasingly studied to enhance radiation effects. Among them, nanodiamonds (NDs) are taken into great consideration due to their low toxicity, inertness, chemical stability, and the possibility of surface functionalization. The objective of this study is to explore the influence of the chemical/physical properties of NDs on cellular radiosensitivity to combined treatments with radiation beams of different energies. DAOY, a human radioresistant medulloblastoma cell line was treated with NDs-differing for surface modifications [hydrogenated (H-NDs) and oxidized (OX-NDs)], size, and concentration-and analysed for (i) ND internalization and intracellular localization, (ii) clonogenic survival after combined treatment with different radiation beam energies and (iii) DNA damage and apoptosis, to explore the nature of ND-radiation biological interactions. Results show that chemical/physical characteristics of NDs are crucial in determining cell toxicity, with hydrogenated NDs (H-NDs) decreasing either cellular viability when administered alone, or cell survival when combined with radiation, depending on ND size and concentration, while OX-NDs do not. Also, irradiation at high energy (γ-rays at 1.25 MeV), in combination with H-NDs, is more efficient in eliciting radiosensitisation when compared to irradiation at lower energy (X-rays at 250 kVp). Finally, the molecular mechanisms of ND radiosensitisation was addressed, demonstrating that cell killing is mediated by the induction of Caspase-3-dependent apoptosis that is independent to DNA damage. Identifying the optimal combination of ND characteristics and radiation energy has the potential to offer a promising therapeutic strategy for tackling radioresistant cancers using H-NDs in conjunction with high-energy radiation.

Critical parameters to translate gold nanoparticles as radiosensitizing agents into the clinic

Radiotherapy is an inevitable choice for cancer treatment that is applied as combinatorial therapy along with surgery and chemotherapy. Nevertheless, radiotherapy at high doses kills normal and tumor cells at the same time. In addition, some tumor cells are resistant to radiotherapy. Recently, many researchers have focused on high-Z nanomaterials as radiosensitizers for radiotherapy. Among them, gold nanoparticles (GNPs) have shown remarkable potential due to their promising physical, chemical, and biological properties. Although few clinical trial studies have been performed on drug delivery and photosensitization with lasers, GNPs have not yet received Food and Drug Administration approval for use in radiotherapy. The sensitization effects of GNPs are dependent on their concentration in cells and x-ray energy deposition during radiotherapy. Notably, some limitations related to the properties of the GNPs, including their size, shape, surface charge, and ligands, and the radiation source energy should be resolved. At the first, this review focuses on some of the challenges of using GNPs as radiosensitizers and some biases among in vitro/in vivo, Monte Carlo, and clinical studies. Then, we discuss the challenges in the clinical translation of GNPs as radiosensitizers for radiotherapy and proposes feasible solutions. And finally, we suggest that certain areas be considered in future research. This article is categorized under: Therapeutic Approaches and Drug Discovery > NA.

A physicochemical model of X-ray induced photodynamic therapy (X-PDT) with an emphasis on tissue oxygen concentration and oxygenation

X-PDT is one of the novel cancer treatment approaches that uses high penetration X-ray radiation to activate photosensitizers (PSs) placed in deep seated tumors. After PS activation, some reactive oxygen species (ROS) like singlet oxygen (1O2) are produced that are very toxic for adjacent cells. Efficiency of X-PDT depends on 1O2 quantum yield as well as X-ray mortality rate. Despite many studies have been modeled X-PDT, little is known about the investigation of tissue oxygen content in treatment outcome. In the present study, we predicted X-PDT efficiency through a feedback of physiological parameters of tumor microenvironment includes tissue oxygen and oxygenation properties. The introduced physicochemical model of X-PDT estimates 1O2 production in a vascularized and non-vascularized tumor under different tissue oxygen levels to predict cell death probability in tumor and adjacent normal tissue. The results emphasized the importance of molecular oxygen and the presence of a vascular network in predicting X-PDT efficiency.

The use of nanomaterials in advancing photodynamic therapy (PDT) for deep-seated tumors and synergy with radiotherapy

Photodynamic therapy (PDT) has been under development for at least 40 years. Multiple studies have demonstrated significant anti-tumor efficacy with limited toxicity concerns. PDT was expected to become a major new therapeutic option in treating localized cancer. However, despite a shifting focus in oncology to aggressive local therapies, PDT has not to date gained widespread acceptance as a standard-of-care option. A major factor is the technical challenge of treating deep-seated and large tumors, due to the limited penetration and variability of the activating light in tissue. Poor tumor selectivity of PDT sensitizers has been problematic for many applications. Attempts to mitigate these limitations with the use of multiple interstitial fiberoptic catheters to deliver the light, new generations of photosensitizer with longer-wavelength activation, oxygen independence and better tumor specificity, as well as improved dosimetry and treatment planning are starting to show encouraging results. Nanomaterials used either as photosensitizers per se or to improve delivery of molecular photosensitizers is an emerging area of research. PDT can also benefit radiotherapy patients due to its complementary and potentially synergistic mechanisms-of-action, ability to treat radioresistant tumors and upregulation of anti-tumoral immune effects. Furthermore, recent advances may allow ionizing radiation energy, including high-energy X-rays, to replace external light sources, opening a novel therapeutic strategy (radioPDT), which is facilitated by novel nanomaterials. This may provide the best of both worlds by combining the precise targeting and treatment depth/volume capabilities of radiation therapy with the high therapeutic index and biological advantages of PDT, without increasing toxicities. Achieving this, however, will require novel agents, primarily developed with nanomaterials. This is under active investigation by many research groups using different approaches.

Evolving role of novel radiosensitizers and immune checkpoint inhibitors in (chemo)radiotherapy of locally advanced head and neck squamous cell carcinoma

Chemoradiotherapy (CRT) remains the standard treatment for locally advanced head and neck squamous cell carcinoma (LA-HNSCC), based on numerous randomized controlled trials and meta-analyses demonstrating that CRT improved locoregional control and overall survival. Achieving locoregional control is a crucial outcome for the treatment of HNSCC, as it directly affects patient quality of life and survival. Cisplatin is the recommended standard-of-care radiosensitizing agent for LA-HNSCC patients undergoing CRT, whereas cetuximab-radiotherapy is reserved for cisplatin-ineligible patients. Immune checkpoint inhibitors (ICIs) have shown promise in the treatment of recurrent or metastatic HNSCC. However, the combination of ICIs with standard-of-care radiotherapy or chemoradiotherapy in LA-HNSCC has not demonstrated significant improvement in survivals. Over the past few decades, significant advancements in radiotherapy techniques have allowed for more precise and effective radiation delivery while minimizing toxicity to surrounding normal tissues. These advances have led to improved treatment outcomes and quality of life for patients with LA-HNSCC. Despite these advancements, the development of novel radiosensitizing agents remains an unmet need. This review discusses the mechanism of radiotherapy and its impact on the immune system. We summarize the latest clinical development of novel radiosensitizing agents, such as SMAC mimetics, DDR pathway inhibitors, and CDK4/6 inhibitor. We also elucidate the emerging evidence of combining ICIs with radiotherapy or chemoradiotherapy in curative settings for LA-HNSCC, using both concurrent and sequential approaches. Lastly, we discuss the future direction of systemic therapy in combination with radiotherapy in treatment for LA-HNSCC.

Zinc-Doped Iron Oxide Nanoparticles as a Proton-Activatable Agent for Dose Range Verification in Proton Therapy

Proton therapy allows the treatment of specific areas and avoids the surrounding tissues. However, this technique has uncertainties in terms of the distal dose fall-off. A promising approach to studying the proton range is the use of nanoparticles as proton-activatable agents that produce detectable signals. For this, we developed an iron oxide nanoparticle doped with Zn (IONP@Zn-cit) with a hydrodynamic size of 10 nm and stability in serum. Cytotoxicity, defined as half of the surveillance, was 100 μg Zn/mL in the U251 cell line. The effect on clonogenic cell death was tested after X-ray irradiation, which suggested a radioprotective effect of these nanoparticles at low concentrations (1-10 μg Zn/mL). To evaluate the production of positron emitters and prompt-gamma signals, IONP@Zn-cit was irradiated with protons, obtaining prompt-gamma signals at the lowest measured concentration (10 mg Zn/mL). Finally, 67Ga-IONP@Zn-cit showed accumulation in the liver and spleen and an accumulation in the tumor tissue of 0.95% ID/g in a mouse model of U251 cells. These results suggest the possibility of using Zn nanoparticles as proton-activatable agents to verify the range by prompt gamma detection and face the challenges of prompt gamma detection in a specific biological situation, opening different avenues to go forward in this field.

Nanomaterials: a promising multimodal theranostics platform for thyroid cancer

Thyroid cancer is the most prevalent malignant neoplasm of the cervical region and endocrine system, characterized by a discernible upward trend in incidence over recent years. Ultrasound-guided fine needle aspiration is the current standard for preoperative diagnosis of thyroid cancer, albeit with limitations and a certain degree of false-negative outcomes. Although differentiated thyroid carcinoma generally exhibits a favorable prognosis, dedifferentiation is associated with an unfavorable clinical course. Anaplastic thyroid cancer, characterized by high malignancy and aggressiveness, remains an unmet clinical need with no effective treatments available. The emergence of nanomedicine has opened new avenues for cancer theranostics. The unique features of nanomaterials, including multifunctionality, modifiability, and various detection modes, enable non-invasive and convenient thyroid cancer diagnosis through multimodal imaging. For thyroid cancer treatment, nanomaterial-based photothermal therapy or photodynamic therapy, combined with chemotherapy, radiotherapy, or gene therapy, holds promise in reducing invasiveness and prolonging patient survival or alleviating pain in individuals with anaplastic thyroid carcinoma. Furthermore, nanomaterials enable simultaneous diagnosis and treatment of thyroid cancer. This review aims to provide a comprehensive survey of the latest developments in nanomaterials for thyroid cancer diagnosis and treatment and encourage further research in developing innovative and effective theranostic approaches for thyroid cancer.

Surface Chemistry and Specific Surface Area Rule the Efficiency of Gold Nanoparticle Sensitizers in Proton Therapy

Gold nanoparticles (AuNPs) are currently the most studied radiosensitizers in proton therapy (PT) applicable for the treatment of solid tumors, where they amplify production of reactive oxygen species (ROS). However, it is underexplored how this amplification is correlated with the AuNPs' surface chemistry. To clarify this issue, we fabricated ligand-free AuNPs of different mean diameters by laser ablation in liquids (LAL) and laser fragmentation in liquids (LFL) and irradiated them with clinically relevant proton fields by using water phantoms. ROS generation was monitored by the fluorescent dye 7-OH-coumarin. Our findings reveal an enhancement of ROS production driven by I) increased total particle surface area, II) utilization of ligand-free AuNPs avoiding sodium citrate as a radical quencher ligands, and III) a higher density of structural defects generated by LFL synthesis, indicated by surface charge density. Based on these findings it may be concluded that the surface chemistry is a major and underexplored contributor to ROS generation and sensitizing effects of AuNPs in PT. We further highlight the applicability of AuNPs in vitro in human medulloblastoma cells.

In vivo Biodistribution and Clearance of Magnetic Iron Oxide Nanoparticles for Medical Applications

Magnetic iron oxide nanoparticles (magnetite and maghemite) are intensively studied due to their broad potential applications in medical and biological sciences. Their unique properties, such as nanometric size, large specific surface area, and superparamagnetism, allow them to be used in targeted drug delivery and internal radiotherapy by targeting an external magnetic field. In addition, they are successfully used in magnetic resonance imaging (MRI), hyperthermia, and radiolabelling. The appropriate design of nanoparticles allows them to be delivered to the desired tissues and organs. The desired biodistribution of nanoparticles, eg, cancerous tumors, is increased using an external magnetic field. Thus, knowledge of the biodistribution of these nanoparticles is essential for medical applications. It allows for determining whether nanoparticles are captured by the desired organs or accumulated in other tissues, which may lead to potential toxicity. This review article presents the main organs where nanoparticles accumulate. The sites of their first uptake are usually the liver, spleen, and lymph nodes, but with the appropriate design of nanoparticles, they can also be accumulated in organs such as the lungs, heart, or brain. In addition, the review describes the factors affecting the biodistribution of nanoparticles, including their size, shape, surface charge, coating molecules, and route of administration. Modern techniques for determining nanoparticle accumulation sites and concentration in isolated tissues or the body in vivo are also presented.

3-Bromopyruvate-loaded bismuth sulfide nanospheres improve cancer treatment by synergizing radiotherapy with modulation of tumor metabolism

BACKGROUND

Radiotherapy (RT) is one of the most mainstream cancer therapeutic modalities. However, due to the lack of specificity of the radiation adopted, both normal and cancerous cells are destroyed indiscriminately. This highlights the crucial need to improve radiosensitization. This study aims to address this issue by constructing a multifunctional nanospheres that can sensitize multiple aspects of radiotherapy.

RESULTS

Nanospheres containing high atomic element Bi can effectively absorb ionizing radiation and can be used as radiosensitizers. Cell viability after Bi₂S₃ + X-ray treatment was half that of X-ray treatment alone. On the other hand, exposed 3-bromopyruvate (3BP) could reduce the overactive oxygen (O₂) metabolism of tumor cells and alleviate tumor hypoxia, thereby promoting radiation-induced DNA damage. The combination index (CI) of 3BP and Bi₂S₃-based RT in Bi₂S₃-3BP + X-ray was determined to be 0.46 with the fraction affected (f_a) was 0.5 via Chou-Talalay's isobolographic method, which indicated synergistic effect of 3BP and Bi₂S₃-based RT after integration into Bi₂S₃-3BP + X-ray. Under the combined effect of 3BP and RT, autophagy was over-activated through starvation-induced and redox homeostasis dysregulation pathways, which in turn exhibited pro-death effects. In addition, the prepared nanospheres possess strong X-ray attenuation and high near-infrared (NIR) optical absorption, thus eliminating the need for additional functional components and could serve as bimodal contrast agents for computed tomography/photoacoustic (CT/PA) imaging.

CONCLUSIONS

The rational design of multifunctional nanospheres with the unique properties provided a novel strategy to achieving high therapeutic efficacy in RT. This was accomplished through simultaneous activation of multiple sensitization pathways by increasing ionizing radiation, reducing tumor oxygen consumption, inducing pro-death autophagy, and providing multiple-imaging guidance/monitoring.

X-ray-responsive prodrugs and polymeric nanocarriers for multimodal cancer therapy

Radiotherapy as one of the most important cancer treatment modalities has been widely used in the therapy of various cancers. The clinically used radiation (e.g. X-ray) for radiotherapy has the advantages of precise spatiotemporal controllability and deep tissue penetration. However, traditional radiotherapy is frequently limited by the high side effects and tumor hypoxia. The combination of radiotherapy and other cancer treatment modalities may overcome the disadvantages of radiotherapy and improve the final therapeutic efficacy. In recent years, X-ray-activable prodrugs and polymeric nanocarriers have been extensively explored to introduce other treatment modalities in the precise position during radiotherapy, which can reduce the side toxicity of the drugs and improve the combination therapeutic efficacy. In this review, we focus on recent advances in X-ray-activable prodrugs and polymeric nanocarriers to boost X-ray-based multimodal synergistic therapy with reduced toxicity. The design strategies of prodrugs and polymeric nanocarriers are highlighted. Finally, challenges and outlooks of X-ray-activable prodrugs and polymeric nanocarriers are discussed.

Reprogramming of the tumor microenvironment using a PCN-224@IrNCs/D-Arg nanoplatform for the synergistic PDT, NO, and radiosensitization therapy of breast cancer and improving anti-tumor immunity

The low X-ray attenuation coefficient of tumor soft tissue and the hypoxic tumor microenvironment (TME) during radiation therapy (RT) of breast cancer result in RT resistance and thus reduced therapeutic efficacy. In addition, immunosuppression induced by the TME severely limits the antitumor immunity of radiation therapy. In this paper, we propose a PCN-224@IrNCs/D-Arg nanoplatform for the synergistic radiosensitization, photodynamic, and NO therapy of breast cancer that also boosts antitumor immunity (PCN = porous coordination network, IrNCs = iridium nanocrystals, D-Arg = D-arginine). The local tumors can be selectively ablated via reprogramming the tumor microenvironment (TME), photodynamic therapy (PDT) and NO therapy, and the presence of the high-Z element Ir that sensitizes radiotherapy. The synergistic execution of these treatment modalities also resulted in adapted antitumor immune response. The intrinsic immunomodulatory effects of the nanoplatform also repolarize macrophages toward the M1 phenotype and induce dendritic cell maturation, activating antitumor T cells to induce immunogenic cell death as demonstrated in vitro and in vivo. The nanocomposite design reported herein represents a new regimen for the treatment of breast cancer through TME reprogramming to exert a synergistic effect for effective cancer therapy and antitumor immunity.

Combining Pr3+-Doped Nanoradiosensitizers and Endogenous Protoporphyrin IX for X-ray-Mediated Photodynamic Therapy of Glioblastoma Cells

Glioblastoma multiforme is an aggressive type of brain cancer with high recurrence rates due to the presence of radioresistant cells remaining after tumor resection. Here, we report the development of an X-ray-mediated photodynamic therapy (X-PDT) system using NaLuF₄:25% Pr³⁺ radioluminescent nanoparticles in conjunction with protoporphyrin IX (PPIX), an endogenous photosensitizer that accumulates selectively in cancer cells. Conveniently, 5-aminolevulinic acid (5-ALA), the prodrug that is administered for PDT, is the only drug approved for fluorescence-guided resection of glioblastoma, enabling dual detection and treatment of malignant cells. NaLuF₄:Pr³⁺ nanoparticles were synthesized and spectroscopically evaluated at a range of Pr³⁺ concentrations. This generated radioluminescent nanoparticles with strong emissions from the ¹S₀ excited state of Pr³⁺, which overlaps with the Soret band of PPIX to perform photodynamic therapy. The spectral overlap between the nanoparticles and PPIX improved treatment outcomes for U251 cells, which were used as a model for the thin tumor margin. In addition to sensitizing PPIX to induce X-PDT, our nanoparticles exhibit strong radiosensitizing properties through a radiation dose-enhancement effect. We evaluate the effects of the nanoparticles alone and in combination with PPIX on viability, death, stress, senescence, and proliferation. Collectively, our results demonstrate this as a strong proof of concept for nanomedicine.

Nanotechnology-based radiation therapy to cure cancer and the challenges in its clinical applications

Radiation therapy against cancer frequently fails to attain the desired outcomes because of several restricting aspects. Radiation therapy is not a targeted antitumor treatment, and it poses serious threats to normal tissues as well. In many cases, some inherent features of tumors make them resistant to radiation therapy. Several nanoparticles have shown the capacity to upgrade the viability of radiation treatment because they can directly interact with ionizing radiation to increase cellular radiation sensitivity. Several types of nanomaterials have been investigated as radio-sensitizers, to improve the efficacy of radiotherapy and overcome radio-resistance including, metal-based nanoparticles, quantum dots, silica-based nanoparticles, polymeric nanoparticles, etc. Despite all this research and development, certain challenges associated with the exploitation of nanoparticles to enhance and improve radiation therapy for cancer treatment are encountered. Potential applications of nanoparticles as radiosensitizers is hindered by the difficulties associated with ensuring their production at a large scale with improved characterizations and because of certain biological challenges. By overcoming the shortcomings of nanoparticles like working on the pharmacokinetics, and physical and chemical characterization, the therapy can be improved. It is expected that in the future more knowledge will be available regarding nanoparticles and their clinical efficacy, leading to the successful development of nanotechnology-based radiation therapies for a variety of cancers. This review highlights the limitations of conventional radiotherapy in cancer treatment and explores the potential of nanotechnology, specifically the use of nanomaterials, to overcome these challenges. It discusses the concept of using nanomaterials to enhance the effectiveness of radiation therapy and provides an overview of different types of nanomaterials and their beneficial properties. The review emphasizes the need to address the obstacles and limitations associated with the application of nanotechnology in cancer radiation therapy for successful clinical translation.

Gold-Nanoparticles-Enhanced Production of Reactive Oxygen Species in Cells at Spread-Out Bragg Peak under Proton Beam Radiation

This study investigates the radiobiological effects of gold nanoparticles (GNPs) as radiosensitizers for proton beam therapy (PBT). Specifically, we explore the enhanced production of reactive oxygen species (ROS) in GNP-loaded tumor cells irradiated by a 230 MeV proton beam in a spread-out Bragg peak (SOBP) zone obtained by a passive scattering system. Our findings indicate that the radiosensitization enhancement factor is 1.24 at 30% cell survival fraction, 8 days after 6 Gy proton beam irradiation. Since protons deposit the majority of their energy at the SOBP region and interact with GNPs to induce more ejected electrons from the high-Z GNPs, these ejected electrons then react with water molecules to produce excessive ROS that can damage cellular organelles. Laser scanning confocal microscopy reveals the excessive ROS induced inside the GNP-loaded cells immediately after proton irradiation. Furthermore, the damage to cytoskeletons and mitochondrial dysfunction in GNP-loaded cells caused by the induced ROS becomes significantly severe, 48 h after proton irradiation. Our biological evidence suggests that the cytotoxicity of GNP-enhanced ROS production has the potential to increase the tumoricidal efficacy of PBT.

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

The Promise of Nanoparticles-Based Radiotherapy in Cancer Treatment

Radiation has been utilized for a long time for the treatment of cancer patients. However, radiotherapy (RT) has many constraints, among which non-selectivity is the primary one. The implementation of nanoparticles (NPs) with RT not only localizes radiation in targeted tissue but also provides significant tumoricidal effect(s) compared to radiation alone. NPs can be functionalized with both biomolecules and therapeutic agents, and their combination significantly reduces the side effects of RT. NP-based RT destroys cancer cells through multiple mechanisms, including ROS generation, which in turn damages DNA and other cellular organelles, inhibiting of the DNA double-strand damage-repair system, obstructing of the cell cycle, regulating of the tumor microenvironment, and killing of cancer stem cells. Furthermore, such combined treatments overcome radioresistance and drug resistance to chemotherapy. Additionally, NP-based RT in combined treatments have shown synergistic therapeutic benefit(s) and enhanced the therapeutic window. Furthermore, a combination of phototherapy, i.e., photodynamic therapy and photothermal therapy with NP-based RT, not only reduces phototoxicity but also offers excellent therapeutic benefits. Moreover, using NPs with RT has shown promise in cancer treatment and shown excellent therapeutic outcomes in clinical trials. Therefore, extensive research in this field will pave the way toward improved RT in cancer treatment.

Tween-20-Modified BiVO4 Nanorods for CT Imaging-Guided Radiotherapy of Tumor

Oral cancer is the most common malignant tumor in the oral and maxillofacial region, which seriously threatens the health of patients. At present, radiotherapy is one of the commonly used methods for oral cancer treatment. However, the resistance of cancerous tissues to ionizing radiation, as well as the side effects of X-rays on healthy tissues, still limit the application of radiotherapy. Therefore, how to effectively solve the above problems is still a challenge at present. Generally speaking, elements with high atomic numbers, such as bismuth, tungsten, and iodine, have a high X-ray attenuation capacity. Using nanomaterials containing these elements as radiosensitizers can greatly improve the radiotherapy effect. At the same time, the modification of nanomaterials based on the above elements with the biocompatible polymer can effectively reduce the side effects of radiosensitizers, providing a new method for the realization of efficient and safe radiotherapy for oral cancer. In this work, we prepared Tween-20-modified BiVO₄ nanorods (Tw20-BiVO₄ NRs) and further used them in the radiotherapy of human tongue squamous cell carcinoma. Tw20-BiVO₄ NRs are promising radiosensitizers, which can generate a large number of free radicals under X-rays, leading to the damage of cancer cells and thus playing a role in tumor therapy. In cell experiments, radiotherapy sensitization of Tw20-BiVO₄ NRs significantly enhanced the production of free radicals in oral cancer cells, aggravated the destruction of chromosomes, and improved the therapeutic effect of radiotherapy. In animal experiments, the strong X-ray absorption ability of Tw20-BiVO₄ NRs makes them effective contrast agents in computed tomography (CT) imaging. After the tumors are located by CT imaging, it helps to apply precise radiotherapy; the growth of subcutaneous tumors in nude mice was significantly inhibited, confirming the remarkable effect of CT imaging-guided radiotherapy.

Improving Radiotherapy Response in the Treatment of Head and Neck Cancer

The application of radiotherapy to the treatment of cancer has existed for over 100 years. Although its use has cured many, much work remains to be done to minimize side effects, and in-field tumor recurrences. Resistance of the tumor to a radiation-mediated death remains a complex issue that results in local recurrence and significantly decreases patient survival. Here, we review mechanisms of radioresistance and selective treatment combinations that improve the efficacy of the radiation that is delivered. Further investigation into the underlying mechanisms of radiation resistance is warranted to develop not just novel treatments, but treatments with improved safety profiles relative to current radiosensitizers. This review is written in memory and honor of Dr. Peter Stambrook, an avid scientist and thought leader in the field of DNA damage and carcinogenesis, and a mentor and advocate for countless students and faculty.

XFCT-MRI hybrid multimodal contrast agents for complementary imaging

Multimodal contrast agents in biomedical imaging enable the collection of more comprehensive diagnostic information. In the present work, we design hybrid ruthenium-decorated superparamagnetic iron oxide nanoparticles (NPs) as the contrast agents for both magnetic resonance imaging (MRI) and X-ray fluorescence computed tomography (XFCT). The NPs are synthesized via a one-pot polyol hot injection route, in diethylene glycol. In vivo preclinical studies demonstrate the possibility of correlative bioimaging with these contrast agents. The complementarity allows accurate localization, provided by the high contrast of the soft tissues in MRI combined with the elemental selectivity of XFCT, leading to NP detection with high specificity and resolution. We envision that this multimodal imaging could find future applications for early tumor diagnosis, improved long-term treatment monitoring, and enhanced radiotherapy planning.

Nanoparticle-Mediated Drug Delivery of Doxorubicin Induces a Differentiated Clonogenic Inactivation in 3D Tumor Spheroids In Vitro

Involvement of 3D tumor cell models in the in vitro biological testing of novel nanotechnology-based strategies for cancer management can provide in-depth information on the real behavior of tumor cells in complex biomimetic architectures. Here, we used polyethylene glycol-encapsulated iron oxide nanoparticles for the controlled delivery of a doxorubicin chemotherapeutic substance (IONP_DOX), and to enhance cytotoxicity of photon radiation therapy. The biological effects of nanoparticles and 150 kV X-rays were evaluated on both 2D and 3D cell models of normal human keratinocytes (HaCaT) and tumor cells-human cervical adenocarcinoma (HeLa) and human squamous carcinoma (FaDu)-through cell survival. In all 2D cell models, nanoparticles were similarly internalized in a peri-nuclear pattern, but resulted in different survival capabilities following radiation treatment. IONP on normal keratinocytes showed a protective effect, but a cytotoxic effect for cancer cells. In 3D tumor cell models, IONP_DOX were able to penetrate the cell spheroids towards the hypoxic areas. However, IONP_DOX and 150 kV X-rays led to a dose-modifying factor DMF_SF=0.1 = 1.09 ± 0.1 (200 µg/mL IONP_DOX) in HeLa spheroids, but to a radioprotective effect in FaDu spheroids. Results show that the proposed treatment is promising in the management of cervical adenocarcinoma.