Actual questions raised by nanoparticle radiosensitization

Oxidative stress and potential effects of metal nanoparticles: A review of biocompatibility and toxicity concerns

Metal nanoparticles (M-NPs) have garnered significant attention due to their unique properties, driving diverse applications across packaging, biomedicine, electronics, and environmental remediation. However, the potential health risks associated with M-NPs must not be disregarded. M-NPs' ability to accumulate in organs and traverse the blood-brain barrier poses potential health threats to animals, humans, and the environment. The interaction between M-NPs and various cellular components, including DNA, multiple proteins, and mitochondria, triggers the production of reactive oxygen species (ROS), influencing several cellular activities. These interactions have been linked to various effects, such as protein alterations, the buildup of M-NPs in the Golgi apparatus, heightened lysosomal hydrolases, mitochondrial dysfunction, apoptosis, cell membrane impairment, cytoplasmic disruption, and fluctuations in ATP levels. Despite the evident advantages M-NPs offer in diverse applications, gaps in understanding their biocompatibility and toxicity necessitate further research. This review provides an updated assessment of M-NPs' pros and cons across different applications, emphasizing associated hazards and potential toxicity. To ensure the responsible and safe use of M-NPs, comprehensive research is conducted to fully grasp the potential impact of these nanoparticles on both human health and the environment. By delving into their intricate interactions with biological systems, we can navigate the delicate balance between harnessing the benefits of M-NPs and minimizing potential risks. Further exploration will pave the way for informed decision-making, leading to the conscientious development of these nanomaterials and safeguarding the well-being of society and the environment.

Stimuli-Responsive Nanoradiosensitizers for Enhanced Cancer Radiotherapy

Radiotherapy (RT) has been a classical therapeutic method of cancer for several decades. It attracts tremendous attention for the precise and efficient treatment of local tumors with stimuli-responsive nanomaterials, which enhance RT. However, there are few systematic reviews summarizing the newly emerging stimuli-responsive mechanisms and strategies used for tumor radio-sensitization. Hence, this review provides a comprehensive overview of recently reported studies on stimuli-responsive nanomaterials for radio-sensitization. It includes four different approaches for sensitized RT, namely endogenous response, exogenous response, dual stimuli-response, and multi stimuli-response. Endogenous response involves various stimuli such as pH, hypoxia, GSH, and reactive oxygen species (ROS), and enzymes. On the other hand, exogenous response encompasses X-ray, light, and ultrasound. Dual stimuli-response combines pH/enzyme, pH/ultrasound, and ROS/light. Lastly, multi stimuli-response involves the combination of pH/ROS/GSH and X-ray/ROS/GSH. By elaborating on these responsive mechanisms and applying them to clinical RT diagnosis and treatment, these methods can enhance radiosensitive efficiency and minimize damage to surrounding normal tissues. Finally, this review discusses the additional challenges and perspectives related to stimuli-responsive nanomaterials for tumor radio-sensitization.

Silver sulfide coated alginate radioenhancer for enhanced X-ray radiation therapy of breast cancer

A wide range of high-Z nanomaterials are fabricated to decrease radiation dose by sensitizing cells to irradiation through various mechanisms such as ROS generation enhancement. Alginate-coated silver sulfide nanoparticles (Ag₂S@Alg) were synthesized and characterized by SEM, TEM, DLS, XRD, EPS, FT-IR, and UV-vis analysis techniques. Cytotoxicity of nanoparticles was tested against HFF-2, MCF-7, and 4 T1 cell lines for biocompatibility and radio enhancement ability evaluation, respectively. Moreover, the hemolysis assay demonstrated that the nanoparticles were biocompatible and nontoxic. In vitro intracellular ROS generation and calcein AM/PI co-staining unveiled cancerous cell death induction by nanoradiosensitizer, Ag₂S@Alg. Further, histopathology results emphasized the tumor ablation capability of Ag₂S@Alg. Silver anticancer properties were also recognized and combined with its radiosensitizing effect under X-ray irradiation.

Nanotechnology in the Diagnosis and Treatment of Osteomyelitis

Infection remains one of the largest threats to global health. Among those infections that are especially troublesome, osteomyelitis, or inflammation of the bone, typically due to infection, is a particularly difficult condition to diagnose and treat. This difficulty stems not only from the biological complexities of opportunistic infections designed to avoid the onslaught of both the host immune system as well as exogenous antibiotics, but also from changes in the host vasculature and the heterogeneity of infectious presentations. While several groups have attempted to classify and stage osteomyelitis, controversy remains, often delaying diagnosis and treatment. Despite a host of preclinical treatment advances being incubated in academic and company research and development labs worldwide, clinical treatment strategies remain relatively stagnant, including surgical debridement and lengthy courses of intravenous antibiotics, both of which may compromise the overall health of the bone and the patient. This manuscript reviews the current methods for diagnosing and treating osteomyelitis and then contemplates the role that nanotechnology might play in the advancement of osteomyelitis treatment.

Gums-based engineered bio-nanostructures for greening the 21st-century biotechnological settings

Naturally occurring plant-based gums and their engineered bio-nanostructures have gained an immense essence of excellence in several industrial, biotechnological, and biomedical sectors of the modern world. Gums derived from bio-renewable resources that follow green chemistry principles are considered green macromolecules with unique structural and functional attributes. For instance, gum mostly obtained as exudates are bio-renewable, bio-degradable, bio-compatible, sustainable, overall cost-effective, and nontoxic. Gum exudates also offer tunable attributes that play a crucial role in engineering bio-nanostructures of interest for several bio- and non-bio applications, e.g., food-related items, therapeutic molecules, sustained and controlled delivery cues, bio-sensing constructs, and so on. With particular reference to plant gum exudates, this review focuses on applied perspectives of various gums, i.e., gum Arabic, gum albizzia, gum karaya, gum tragacanth, and gum kondagogu. After a brief introduction with problem statement and opportunities, structural and physicochemical attributes of plant-based natural gums are presented. Following that, considerable stress is given to green synthesis and stabilization of gum-based bio-nanostructures. The final part of the review focuses on the bio- and non-bio related applications of various types of gums polysaccharides-oriented bio-nanostructures.

First observation of radiolytic bubble formation in unstirred nano-powder sludges and a consistent model thereof

Experiments involving the irradiation of water contained within magnesium hydroxide and alumina nanoparticle sludges were conducted and culminated in observations of an increased yield of molecular hydrogen when compared to the yield from the irradiation of bulk water. We show that there is a relationship linking this increased yield to the direct nanoscale ionization mechanism in the nanoparticles, indicating that electron emission from the nanoparticles drives new radiative pathways in the water. Because the chemical changes in these sludges are introduced by irradiation only, we have a genuinely unstirred system. This feature allows us to determine the diffusivity of the dissolved gas. Using the measured gas production rate, we have developed a method for modelling when hydrogen bubble formation will occur within the nanoparticle sludges. This model facilitates the determination of a consistent radiolytic consumption rate coinciding with the observations of bubble formation. Thus, we demonstrate a nanoscale radiation effect directly influencing the formation of molecular hydrogen.

One Pot Synthesis of PEGylated Bimetallic Gold-Silver Nanoparticles for Imaging and Radiosensitization of Oral Cancers

Background

Radiotherapy is an important treatment modality for many types of head and neck squamous cell carcinomas. Nanomaterials comprised of high atomic number (Z) elements are novel radiosensitizers enhance radiation injury by production of free radicals and subsequent DNA damage. Gold nanoparticles are upcoming as promising radiosensitizers due to their high (Z) biocompatibility, and ease for surface engineering. Bimetallic nanoparticles have shown enhanced anticancer activity compared to monometallic nanoparticles.

Materials and Methods

PEG-coated Au–Ag alloy nanoparticles (BNPs) were synthesized using facile one pot synthesis techniques. Size of ~50±5nm measured by dynamic light scattering. Morphology, structural composition and elemental mapping were analyzed by electron microscopy and SAXS (small-angle X-ray scattering). The radiosensitization effects on KB oral cancer cells were evaluated by irradiation with 6MV X-rays on linear accelerator. Nuclear damage was imaged using confocal microscopy staining cells with Hoechst stain. Computed tomography (CT) contrast enhancement of BNPs was compared to that of the clinically used agent, Omnipaque.

Results

BNPs were synthesized using PEG 600 as reducing and stabilizing agent. The surface charge of well dispersed colloidal BNPs solution was −5mV. Electron microscopy reveals spherical morphology. HAADF-STEM and elemental mapping studies showed that the constituent metals were Au and Ag intermixed nanoalloy. Hydrodynamic diameter was ~50±5nm due to PEG layer and water molecules absorption. SAXS measurement confirmed BNPs size around 35nm. Raman shift of around 20 cm⁻¹ was observed when BNPs were coated with PEG. ¹H NMR showed extended involvement of ⁻OH in synthesis. BNPs efficiently enter cytoplasm of KB cells and demonstrated potent in vitro radiosensitization with enhancement ratio ~1.5–1.7. Imaging Hoechst-stained nuclei demonstrated apoptosis in a dose-dependent manner. BNPs exhibit better CT contrast enhancement ability compared to Omnipaque.

Conclusion

This bimetallic intermix nanoparticles could serve a dual function as radiosensitizer and CT contrast agent against oral cancers, and by extension possibly other cancers as well.

Engineering of bioactive metal sulfide nanomaterials for cancer therapy

Metal sulfide nanomaterials (MeSNs) are a novel class of metal-containing nanomaterials composed of metal ions and sulfur compounds. During the past decade, scientists found that the MeSNs engineered by specific approaches not only had high biocompatibility but also exhibited unique physicochemical properties for cancer therapy, such as Fenton catalysis, light conversion, radiation enhancement, and immune activation. To clarify the development and promote the clinical transformation of MeSNs, the first section of this paper describes the appropriate fabrication approaches of MeSNs for medical science and analyzes the features and limitations of each approach. Secondly, we sort out the mechanisms of functional MeSNs in cancer therapy, including drug delivery, phototherapy, radiotherapy, chemodynamic therapy, gas therapy, and immunotherapy. It is worth noting that the intact MeSNs and the degradation products of MeSNs can exert different types of anti-tumor activities. Thus, MeSNs usually exhibit synergistic antitumor properties. Finally, future expectations and challenges of MeSNs in the research of translational medicine are spotlighted.

Radiosensitizing effects of citrate-coated cobalt and nickel ferrite nanoparticles on breast cancer cells

Aim: Evaluation of the biocompatibility and radiosensitizer potential of citrate-coated cobalt (cit-CF) and nickel (cit-NF) ferrite nanoparticles (NPs). Materials & methods: Normal fibroblast and breast cancer cells were treated with different concentrations of citrate-coated ferrite NPs (cit-NPs) and irradiated with a cobalt-60 source at doses of 1 and 3 Gy. After 24 h, cell metabolism, morphology alterations and nanoparticle uptake were evaluated. Results: Cit-CF and cit-NF NPs showed no toxicity to normal cells up to 250 and 100 μg.ml^-1, respectively. Combination of cit-NP and ionizing radiation resulted in up to fivefold increase in the radiation therapeutic efficacy against breast cancer cells. Conclusion: Cit-CF and cit-NF NPs are suitable candidates for application as breast cancer cell radiosensitizers.

A Short Review on Biomedical Applications of Nanostructured Bismuth Oxide and Related Nanomaterials

In this review, we reported the main achievements reached by using bismuth oxides and related materials for biological applications. We overviewed the complex chemical behavior of bismuth during the transformation of its compounds to oxide and bismuth oxide phase transitions. Afterward, we summarized the more relevant studies regrouped into three categories based on the use of bismuth species: (i) active drugs, (ii) diagnostic and (iii) theragnostic. We hope to provide a complete overview of the great potential of bismuth oxides in biological environments.

Synergetic Influence of Bismuth Oxide Nanoparticles, Cisplatin and Baicalein-Rich Fraction on Reactive Oxygen Species Generation and Radiosensitization Effects for Clinical Radiotherapy Beams

Purpose

This study aimed to quantify synergetic effects induced by bismuth oxide nanoparticles (BiONPs), cisplatin (Cis) and baicalein-rich fraction (BRF) natural-based agent on the reactive oxygen species (ROS) generation and radiosensitization effects under irradiation of clinical radiotherapy beams of photon, electron and HDR-brachytherapy. The combined therapeutic responses of each compound and clinical radiotherapy beam were evaluated on breast cancer and normal fibroblast cell line.

Methods

In this study, individual BiONPs, Cis, and BRF, as well as combinations of BiONPs-Cis (BC), BiONPs-BRF (BB) and BiONPs-Cis-BRF (BCB) were treated to the cells before irradiation using HDR brachytherapy with 0.38 MeV iridium-192 source, 6 MV photon beam and 6 MeV electron beam. The individual or synergetic effects from the application of the treatment components during the radiotherapy were elucidated by quantifying the ROS generation and radiosensitization effects on MCF-7 and MDA-MB-231 breast cancer cell lines as well as NIH/3T3 normal cell line.

Results

The ROS generated in the presence of Cis stimulated the most substantial amount of ROS compared to the BiONPs and BRF. Meanwhile, the combination of the components had induced the higher ROS levels for photon beam than the brachytherapy and electron beam. The highest ROS enhancement relative to the control is attributable to the presence of BC combination in MDA-MB-231 cells, in comparison to the BB and BCB combinations. The radiosensitization effects which were quantified using the sensitization enhancement ratio (SER) indicate the highest value by BC in MCF-7 cells, followed by BCB and BB treatment. The radiosensitization effects are found to be more prominent for brachytherapy in comparison to photon and electron beam.

Conclusion

The BiONPs, Cis and BRF are the potential radiosensitizers that could improve the efficiency of radiotherapy to eradicate the cancer cells. The combination of these potent radiosensitizers might produce multiple effects when applied in radiotherapy. The BC combination is found to have the highest SER, followed by the BCB combination. This study is also the first to investigate the effect of BRF in combination with BiONPs (BB) and BC (BCB) treatments.

Mechanisms of nanoparticle radiosensitization

Metal-based nanoparticles applied to potentiating the effects of radiotherapy have drawn significant attention from the research community and are now available clinically. By improving our mechanistic understanding, nanoparticles are likely to evolve to provide very significant improvements in radiotherapy outcomes with only incremental increase in cost. This review critically assesses the inconsistent observations surrounding physical, physicochemical, chemical and biological mechanisms of radiosensitization. In doing so, a number of needs are identified for continuing research and are highlighted. The large degree of variability from one nanoparticle to another emphasizes that it is a mistake to generalize nanoparticle radiosensitizer mechanisms. Nanoparticle formulations should be considered in an analogous way as pharmacological agents and as a broad class of therapeutic agents, needing to be considered with a high degree of individuality with respect to their interactions and ultimate impact on radiobiological response. In the same way that no universal anti-cancer drug exists, it is unlikely that a single nanoparticle formulation will lead to the best therapeutic outcomes for all cancers. The high degree of complexity and variability in mechanistic action provides notable opportunities for nanoparticle formulations to be optimized for specific indications. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Systematic quantification of nanoscopic dose enhancement of gold nanoparticles in ion beams

High-Z material nanoparticles are being studied as localized dose enhancers in radiotherapeutic applications. Here, the nano-scale physical dose enhancement of proton, carbon and oxygen ion beam radiation by gold nanoparticles was studied by means of Monte Carlo track structure simulation with the TRAX code. We present 2D distributions and radial profiles of the additional dose and the dose enhancement factor for two geometries which consider an isolated and a water-embedded nanoparticle, respectively. Different nanoparticle sizes (radius of 1.2-22 nm) were found to yield qualitatively different absolute and relative dose enhancement distributions and different maximum dose enhancement factors (up to 20). Whereas the smallest nanoparticles produced the highest local dose enhancement factor close to the metal, larger ones led to lower, more diffuse dose enhancement factors that contributed more at larger distances. Differential absorption effects inside the metal were found to be responsible for those characteristics. For the energy range 15-204 MeVu^-1, also a mild trend with ion E/A, regardless of the ion species, was found for embedded nanoparticles. In analogy to the width of the ion track itself, slower ions increased the enhancement at the nanoparticle surface. In contrast, no dependence on linear energy transfer was encountered. For slower ions (3-10 MeVu^-1), the enhancement effect began to break down over all distances. Finally, the significance of any indirect physical effect was excluded, giving important hints especially in view of the low probabilities (at realistic concentrations and fluences) of direct ion-NP-hits. The very localized nature of the physical dose enhancement found suggests a strong action upon targets closeby, but no relevant effect at cellular distances. When pondering different possible damage enhancement mechanisms of gold nanoparticles in the context of published in vitro and in vivo experimental results, biological pathways are likely to play the key role.

Platinum-gold nanoraspberries as effective photosensitizer in anticancer photothermal therapy

BACKGROUND

New nanophotosensitizers for photothermal cancer therapy (PTT) are still sought. In this paper we propose fancy shaped, non agglomerated core/shell PtAu NRs nanoraspberries (PtAu NRs) as potential nanophotosensitizers in PTT.

RESULTS

Light microscopy images of two colon cancer cell lines (SW480, SW620) showed, that the laser irradiation combined with PtAu NRs caused visible changes in the cell morphology. Fourier Transform InfraRed (FTIR) and Raman spectroscopies showed chemical changes in the DNA, phospholipids, lipids and protein structures caused by laser irradiation in the presence of PtAu NRs. The MTS assay showed ~ 25% mortality of cancer cells due to the addition of PtAu NRs to the cell culture, while for laser irradiation combined with nanoparticles, the mortality of cancer cells increased to 65% for the 650 nm laser and to 60% for the 808 nm laser. The calculated photothermal conversion efficiency reached 62% and 51% for the 650 nm and 808 nm lasers, respectively.

CONCLUSIONS

PtAu NRs could be applied as effective light-absorbers in the PTT anticancer therapy.

Physical, chemical and biological enhancement in X-ray nanochemistry

X-ray nanochemistry studies how to use nanomaterials and particularly how to create new nanomaterials to increase the effects of X-rays such as chemical reactivity, damage to cells, tumor destruction, scintillation and more. The increase, also called enhancement, can be categorized into several groups, and the current categorization of enhancement follows a natural division of physical, chemical and biological enhancement based on how nanomaterials behave under X-ray irradiation. In physical enhancement, electrons released from atoms in the nanomaterials upon X-ray ionization interact with the nanomaterials and surrounding media to increase the effects. Scintillation also belongs to this category. Chemical enhancement results when reactive oxygen species (ROS) or reactive radical intermediates (RRI) produced in aqueous solutions under X-ray irradiation interact with the surface of catalytic nanomaterials to increase the effects. When the damage of cells is enhanced through biological pathways beyond the abovementioned physical or chemical enhancement due to the presence of nanomaterials under X-ray irradiation, the enhancement is called biological enhancement. Works supporting this systematic categorization, the reported values of these enhancements, and important aspects of the development of enhancement in the X-ray nanochemistry framework are given and discussed in this perspective.

A Water Solvation Shell Can Transform Gold Metastable Nanoparticles in the Fluxional Regime

Solvated gold nanoparticles have been modeled in the fluxional regime by density functional theory including dispersion forces for an extensive set of conventional morphologies. The study of isolated adsorption of one water molecule shows that the most stable adsorption forms are similar (corners and edges) regardless of the nanoparticle shape and size, although the adsorption strength differs significantly (0.15 eV). When a complete and explicit water solvation shell interacts with gold nanoclusters, metastable in vacuum and presenting a predominance of (100) square facets (ino-decahedra Au₅₅ and Au₁₄₇), these nanoparticles are found unstable and transform into the closest morphologies exhibiting mainly (111) triangular facets and symmetries. The corresponding adsorption strength per water molecule becomes independent of shape and size and is enhanced by the formation of two hydrogen bonds on average. For applications in radiotherapy, this study suggests that the shapes of small gold nanoparticles should be homogenized by interacting with the biological environment.

Emerging Strategies of Nanomaterial-Mediated Tumor Radiosensitization

Nano-radiosensitization has been a hot concept for the past ten years, and the nanomaterial-mediated tumor radiosensitization method is mainly focused on increasing intracellular radiation deposition by high atomic number (high Z) nanomaterials, particularly gold (Au)-mediated radiation enhancement. Recently, various new nanomaterial-mediated radiosensitive approaches have been successively reported, such as catalyzing reactive oxygen species (ROS) generation, consuming intracellular reduced glutathione (GSH), overcoming tumor hypoxia, and various synergistic radiotherapy ways. These strategies may open a new avenue for enhancing the radiotherapeutic effect and avoiding its side effects. Nevertheless, reviews systematically summarizing these newly emerging methods and their radiosensitive mechanisms are still rare. Therefore, the general strategies of nanomaterial-mediated tumor radiosensitization are comprehensively summarized, particularly aiming at introducing the emerging radiosensitive methods. The strategies are divided into three general parts. First, methods on account of the intrinsic radiosensitive properties of nanoradiosensitizers for radiosensitization are highlighted. Then, newly developed synergistic strategies based on multifunctional nanomaterials for enhancing radiotherapy efficacy are emphasized. Third, nanomaterial-mediated radioprotection approaches for increasing the radiotherapeutic ratio are discussed. Importantly, the clinical translation of nanomaterial-mediated tumor radiosensitization is also covered. Finally, further challenges and outlooks in this field are discussed.

Applications of Noble Metal-Based Nanoparticles in Medicine

Nanoparticles have unique, size-dependent properties, which means they are widely used in various branches of industry. The ability to control the properties of nanoparticles makes these nanomaterials very interesting for medicine and pharmacology. The application of nanoparticles in medicine is associated with the design of specific nanostructures, which can be used as novel diagnostic and therapeutic modalities. There are a lot of applications of nanoparticles, e.g., as drug delivery systems, radiosensitizers in radiation or proton therapy, in bioimaging, or as bactericides/fungicides. This paper aims to introduce the characteristics of noble metal-based nanoparticles with particular emphasis on their applications in medicine and related sciences.