Gold nanoparticles, radiations and the immune system: Current insights into the physical mechanisms and the biological interactions of this new alliance towards cancer therapy

Biocompatible cellulose nanocrystal-based Trojan horse enables targeted delivery of nano-Au radiosensitizers to triple negative breast cancer cells

A hybrid cellulose-based programmable nanoplatform for applications in precision radiation oncology is described. Here, sugar heads work as tumor targeting moieties and steer the precise delivery of radiosensitizers, i.e. gold nanoparticles (AuNPs) into triple negative breast cancer (TNBC) cells. This "Trojan horse" approach promotes a specific and massive accumulation of radiosensitizers in TNBC cells, thus avoiding the fast turnover of small-sized AuNPs and the need for high doses of AuNPs for treatment. Application of X-rays resulted in a significant increase of the therapeutic effect while delivering the same dose, showing the possibility to use roughly half dose of X-rays to obtain the same radiotoxicity effect. These data suggest that this hybrid nanoplatform acts as a promising tool for applications in enhancing cancer radiotherapy effects with lower doses of X-rays.

Tackling breast cancer with gold nanoparticles: twinning synthesis and particle engineering with efficacy

The World Health Organization identifies breast cancer as the most prevalent cancer despite predominantly affecting women. Surgery, hormonal therapy, chemotherapy, and radiation therapy are the current treatment modalities. Site-directed nanotherapeutics, engineered with multidimensional functionality are now the frontrunners in breast cancer diagnosis and treatment. Gold nanoparticles with their unique colloidal, optical, quantum, magnetic, mechanical, and electrical properties have become the most valuable weapon in this arsenal. Their advantages include facile modulation of shape and size, a high degree of reproducibility and stability, biocompatibility, and ease of particle engineering to induce multifunctionality. Additionally, the surface plasmon oscillation and high atomic number of gold provide distinct advantages for tailor-made diagnosis, therapy or theranostic applications in breast cancer such as photothermal therapy, radiotherapy, molecular labeling, imaging, and sensing. Although pre-clinical and clinical data are promising for nano-dimensional gold, their clinical translation is hampered by toxicity signs in major organs like the liver, kidneys and spleen. This has instigated global scientific brainstorming to explore feasible particle synthesis and engineering techniques to simultaneously improve the efficacy and versatility and widen the safety window of gold nanoparticles. The present work marks the first study on gold nanoparticle design and maneuvering techniques, elucidating their impact on the pharmacodynamics character and providing a clear-cut scientific roadmap for their fast-track entry into clinical practice.

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.

Morphological Effects and In Vitro Biological Mechanisms of Radiation-Induced Cell Killing by Gold Nanomaterials

Gold nanomaterials have been shown to augment radiation therapy both in vitro and in vivo. However, studies on these materials are mostly phenomenological due to nanoparticle heterogeneity and the complexity of biological systems. Even accurate quantification of the particle dose still results in bulk average biases; the effect on individual cells is not measured but rather the effect on the overall population. To perform quantitative nanobiology, we coated glass coverslips uniformly at varying densities with Au nanoparticle preparations with different morphologies (45 nm cages, 25 nm spheres, and 30 nm rods). Consequently, the effect of a specific number of particles per unit area in contact with breast cancer cells growing on the coated surfaces was ascertained. Gold nanocages showed the highest degree of radiosensitization on a per particle basis, followed by gold nanospheres and gold nanorods, respectively. All three materials showed little cytotoxic effect at 0 Gy, but clonogenic survival decreased proportionally with the radiation dose and particle coverage density. A similar trend was seen in vivo in the combined treatment antitumor response in 4T1 tumor-bearing animals. The presence of gold affected the type and quantity of reactive oxygen species generated, specifically superoxide and hydroxyl radicals, and the concentration of nanocages correlated with the development of more numerous double-stranded DNA breaks and increased protein oxidation as measured by carbonylation. This work demonstrates the dependence on morphology and concentration of radiation enhancement by gold nanomaterials and may lead to a novel method to differentiate intra- and extracellular functionalities of gold nanomedicine treatment strategies. It further provides insights that can guide the rational development of gold nanomaterial-based radiosensitizers for clinical use.

The Refined Application and Evolution of Nanotechnology in Enhancing Radiosensitivity During Radiotherapy: Transitioning from Gold Nanoparticles to Multifunctional Nanomaterials

Radiotherapy is a pivotal method for treating malignant tumors, and enhancing the therapeutic gain ratio of radiotherapy through physical techniques is the direction of modern precision radiotherapy. Due to the inherent physical properties of high-energy radiation, enhancing the therapeutic gain ratio of radiotherapy through radiophysical techniques inevitably encounters challenges. The combination of hyperthermia and radiotherapy can enhance the radiosensitivity of tumor cells, reduce their radioresistance, and holds significant clinical utility in radiotherapy. Multifunctional nanomaterials with excellent biocompatibility and safety have garnered widespread attention in tumor hyperthermia research, demonstrating promising potential. Utilizing nanotechnology as a sensitizing carrier in conjunction with radiotherapy, and high atomic number nanomaterials can also serve independently as radiosensitizing carriers. This synergy between tumor hyperthermia and radiotherapy may overcome many challenges currently limiting tumor radiotherapy, offering new opportunities for its further advancement. In recent years, the continuous progress in the synthesis and design of novel nanomaterials will propel the future development of medical imaging and cancer treatment. This article summarizes the radiosensitizing mechanisms and effects based on gold nanotechnology and provides an overview of the advancements of other nanoparticles (such as bismuth-based nanomaterials, magnetic nanomaterials, selenium nanomaterials, etc.) in the process of radiation therapy.

Methodological and Cellular Factors Affecting the Magnitude of Breast Cancer and Normal Cell Radiosensitization Using Gold Nanoparticles

Purpose

Breast cancer (BC) is the most common malignant tumor in women, which most often originates from the epithelial tissue of the breast gland. One of the most recommended kinds of treatment is radiotherapy (RT), but irradiation (IR) can affect not only the cancer tumor but also the healthy tissue around it. Au nanoparticles (AuNPs) were proposed as a radiosensitizing agent for RT which would allow for lower radiation doses, reducing the negative radiation effects on healthy tissues. The main objective of the study is to assess the dependence on the radiosensitivity of BC (MDA-MB-231) and normal mammary gland epithelial cells (MCF12A) to ionizing radiation, caused by functionalized AuNPs under diverse conditions.

Methods

The viability, uptake, reactive oxygen species induction, and mitochondrial membrane potential in cells were analyzed applying a time and concentration-dependent manner. After different incubation times with AuNPs, cells were exposed to 2 Gy. The determination of radiation effect in combination with AuNPs was investigated using the clonogenic assay, p53, and γH2AX level, as well as, Annexin V staining.

Results

Our results highlighted the strong need for assessing the experimental conditions' optimization before the AuNPs will be implemented with IR. Moreover, results indicated that AuNPs did not act universally in cells.

Conclusion

AuNPs could be a promising tool as a radiotherapy sensitizing agent, but it should be specified and deeply investigated under what conditions it will be applied taking into consideration not only AuNPs modifications but also the model and experimental conditions.

Gold Nanoparticles: Construction for Drug Delivery and Application in Cancer Immunotherapy

Cancer immunotherapy is an innovative treatment strategy to enhance the ability of the immune system to recognize and eliminate cancer cells. However, dose limitations, low response rates, and adverse immune events pose significant challenges. To address these limitations, gold nanoparticles (AuNPs) have been explored as immunotherapeutic drug carriers owing to their stability, surface versatility, and excellent optical properties. This review provides an overview of the advanced synthesis routes for AuNPs and their utilization as drug carriers to improve precision therapies. The review also emphasises various aspects of AuNP-based immunotherapy, including drug loading, targeting strategies, and drug release mechanisms. The application of AuNPs combined with cancer immunotherapy and their therapeutic efficacy are briefly discussed. Overall, we aimed to provide a recent understanding of the advances, challenges, and prospects of AuNPs for anticancer applications.

Quantitative Analysis of Photothermal Therapy of Tumor Tissue Using Various Gold Nanoparticle Injection Schemes

Photothermal therapy is a new chemotherapy technique using photothermal effects, a phenomenon in which light energy is converted into thermal energy. Since the treatment technique is performed without surgical incision, it does not cause bleeding and patients are expected to make rapid recoveries, which are significant advantages. In this study, photothermal therapy with direct injection of gold nanoparticles into tumor tissue was simulated through numerical modeling. The treatment effect resulting from changing the intensity of the irradiated laser, volume fraction of the injected gold nanoparticles, and number of gold nanoparticle injections was quantitatively evaluated. The discrete dipole approximation method was applied to calculate the optical properties of the entire medium, and the Monte Carlo method was applied to identify the absorption and scattering behavior of lasers in tissue. In addition, by confirming the temperature distribution of the entire medium through the calculated light absorption distribution, the treatment effect of photothermal therapy was evaluated, and the optimal treatment conditions were suggested. This is expected to accelerate the popularization of photothermal therapy in the future.

Albumin-Modified Gold Nanoparticles as Novel Radiosensitizers for Enhancing Lung Cancer Radiotherapy

Background

Considering the strong attenuation of photons and the potential to increase the deposition of radiation, high-atomic number nanomaterials are often used as radiosensitizers in cancer radiotherapy, of which gold nanoparticles (GNPs) are widely used.

Materials and Methods

We prepared albumin-modified GNPs (Alb-GNPs) and observed their radiosensitizing effects and biotoxicity in human non-small-cell lung carcinoma tumor-bearing mice models.

Results

The prepared nanoparticles (Alb-GNPs) demonstrated excellent colloidal stability and biocompatibility at the mean size of 205.06 ± 1.03 nm. Furthermore, clone formation experiments revealed that Alb-GNPs exerted excellent radiosensitization, with a sensitization enhancement ratio (SER) of 1.432, which is higher than X-ray alone. Our in vitro and in vivo data suggested that Alb-GNPs enabled favorable accumulation in tumors, and the combination of Alb-GNPs and radiotherapy exhibited a relatively greater radiosensitizing effect and anti-tumor activity. In addition, no toxicity or abnormal irritating response resulted from the application of Alb-GNPs.

Conclusion

Alb-GNPs can be used as an effective radiosensitizer to improve the efficacy of radiotherapy with minimal damage to healthy tissues.

Development of Ag-ZnO/AgO Nanocomposites Effectives for Leishmania braziliensis Treatment

Tegumentary leishmaniasis (TL) is caused by parasites of the genus Leishmania. Leishmania braziliensis (L.b) is one of the most clinically relevant pathogens that affects the skin and mucosa, causing single or multiple disfiguring and life-threatening injuries. Even so, the few treatment options for patients have significant toxicity, high dropout rates, high cost, and the emergence of resistant strains, which implies the need for studies to promote new and better treatments to combat the disease. Zinc oxide nanocrystals are microbicidal and immunomodulatory agents. Here, we develop new Ag-ZnO/xAgO nanocomposites (NCPs) with three different percentages of silver oxide (AgO) nanocrystals (x = 49%, 65%, and 68%) that could act as an option for tegumentary leishmaniasis treatment. Our findings showed that 65% and 68% of AgO inhibit the extra and intracellular replication of L.b. and present a high selectivity index. Ag-ZnO/65%AgO NCPs modulate activation, expression of surface receptors, and cytokine production by human peripheral blood mononuclear cells toward a proinflammatory phenotype. These results point to new Ag-ZnO/AgO nanocomposites as a promising option for L. braziliensis treatment.

The significance of nanoparticles in brain cancer diagnosis and treatment: modeling and simulation

A numerical analysis of specific absorption rate (SAR) and temperature distributions in a realistic human head model is presented in this study. The key challenge is to rise cancer temperature to an optimal temperature without heating nearby healthy tissues. The model's uniqueness is that it captures the effect of nanoparticles on both brain cancer diagnosis and treatment. A realistic human head model with a cancerous brain segmented from 2D magnetic resonance imaging (MRI) gained from an actual patient using 3D Slicer, modeled, and simulated using CST-Microwave Studio, and illuminated by Archimedes spiral antenna. At frequencies of 2450 MHz and 915 MHz, the model simulated the absence and presence of various nanoparticles. The obtained results suggest that when using nanoparticles, it is possible to achieve sufficient energy deposition and temperature rise to therapeutic values (greater than 42 °C) in brain cancers using the proposed noninvasive hyperthermia system at 915 MHz frequency, especially for gold nanoparticles, without harming surrounding healthy tissue. Our research might pave the way for a clinical applicator prototype that can heat brain cancer.

Dark-Field Microscopic Study of Cellular Uptake of Carbon Nanodots: Nuclear Penetrability

Carbon nanodots are fascinating candidates for the field of biomedicine, in applications such as bioimaging and drug delivery. However, the nuclear penetrability and process are rarely studied and lack understanding, which limits their applications for drug carriers, single-molecule detection and live cell imaging. In this study, we attempt to examine the uptake of CNDs in cells with a focus on the potential nuclear penetrability using enhanced dark-field microscopy (EDFM) associated with hyperspectral imaging (HSI) to quantitatively determine the light scattering signals of CNDs in the cells. The effects of both CND incubation time and concentration are investigated, and plausible nuclear penetration involving the nuclear pore complex (NPC) is discussed. The experimental results and an analytical model demonstrate that the CNDs’ uptake proceeds by a concentration-dependent three-stage behavior and saturates at a CND incubation concentration larger than 750 µg/mL, with a half-saturated concentration of 479 μg/mL. These findings would potentially help the development of CNDs’ utilization in drug carriers, live cell imaging and other biomedical applications.

In Silico, Combined Plasmonic Photothermal and Photodynamic Therapy in Mice

Plasmonic photothermal and photodynamic therapy (PPTT and PDT, respectively) are two cancer treatments that have the potential to be combined in a synergistic scheme. The aim of this study is to optimize the PPTT treatment part, in order to account for the PDT lack of coverage in the hypoxic tumor volume and in cancer areas laying in deep sites. For the needs of this study, a mouse was modeled, subjected to PDT and its necrotic area was estimated by using the MATLAB software. The same procedure was repeated for PPTT, using COMSOL Multiphysics. PPTT treatment parameters, namely laser power and irradiation time, were optimized in order to achieve the optimum therapeutic effect of the combined scheme. The PDT alone resulted in 54.8% tumor necrosis, covering the upper cancer layers. When the PPTT was also applied, the total necrosis percentage raised up to 99.3%, while all of the surrounding studied organs (skin, heart, lungs and trachea, ribs, liver and spleen) were spared. The optimized values of the PPTT parameters were 550 mW of laser power and 70 s of irradiation time. Hence, the PPTT–PDT combination shows great potential in achieving high levels of tumor necrosis while sparing the healthy tissues.

Adaptation of a Bacterial Bioluminescent Assay to Monitor Bioeffects of Gold Nanoparticles

Our current study aimed to adapt a bioluminescent bacteria-based bioassay to monitor the bioeffects of gold nanoparticles (AuNPs). Luminous marine bacteria Photobacterium phosphoreum and AuNPs modified with polyvinylpyrrolidone were employed; low-concentration (≤10−3 g/L) bioeffects of AuNPs were studied. Bioluminescence intensity was used as an indicator of physiological activity in bacteria. Two additional methods were used: reactive oxygen species (ROS) content was estimated with a chemiluminescent luminol method, and bacterial size was monitored using electron microscopy. The bacterial bioluminescent response to AuNPs corresponded to the “hormesis” model and involved time-dependent bioluminescence activation, as well as a pronounced increase in the number of enlarged bacteria. We found negative correlations between the time courses of bioluminescence and the ROS content in bacterial suspensions, demonstrating the relationship between bioluminescence activation and bacterial ROS consumption. The combined effects of AuNPs and a beta-emitting radionuclide, tritium, revealed suppression of bacterial bioluminescent activity (as compared to their individual effects) and a reduced percentage of enlarged bacteria. Therefore, we demonstrated that our bacteria-based bioluminescence assay is an appropriate tool to study the bioeffects of AuNPs; the bioeffects can be further classified within a unified framework for rapid bioassessment.

The Most Recent Discoveries in Heterocyclic Nanoformulations for Targeted Anticancer Therapy

Every day, new cases of cancer patients whose recovery is delayed by multidrug resistance and chemotherapy side effects are identified, which severely limit treatment options. One of the most recent advances in nanotechnology is the effective usage of nanotechnology as drug carriers for cancer therapy. As a consequence, heterocyclic nanocarriers were put into practice to see whether they could have a better cure with positive results. The potential of a therapeutic agent to meet its desired goal is vital to its success in treating any disease. Heterocyclic moieties are molecules that have a wide variety of chemically therapeutic functions as well as a significant biological activity profile. Heterocyclic nano formulations play an important role in cell physiology and as possible arbitrators for typical biological reactions, making them valuable in cancer research. As a result, experts are working with heterocyclic nanoformulations to discover alternative approaches to treat cancer. Due to their unique physicochemical properties, heterocyclic compounds are real cornerstones in medicinal chemistry and promising compounds for the future drug delivery system. This review briefly explores the therapeutic relevance of heterocyclic compounds in cancer treatment, the various nanoformulations, and actively describes heterocyclic magnetic nano catalysts and heterocyclic moiety, as well as their mode of action, which have favorable anti - cancer effects.

Targeted and Non-Targeted Mechanisms for Killing Hypoxic Tumour Cells-Are There New Avenues for Treatment?

Purpose: A major issue in radiotherapy is the relative resistance of hypoxic cells to radiation. Historic approaches to this problem include the use of oxygen mimetic compounds to sensitize tumour cells, which were unsuccessful. This review looks at modern approaches aimed at increasing the efficacy of targeting and radiosensitizing hypoxic tumour microenvironments relative to normal tissues and asks the question of whether non-targeted effects in radiobiology may provide a new “target”. Novel techniques involve the integration of recent technological advancements such as nanotechnology, cell manipulation, and medical imaging. Particularly, the major areas of research discussed in this review include tumour hypoxia imaging through PET imaging to guide carbogen breathing, gold nanoparticles, macrophage-mediated drug delivery systems used for hypoxia-activate prodrugs, and autophagy inhibitors. Furthermore, this review outlines several features of these methods, including the mechanisms of action to induce radiosensitization, the increased accuracy in targeting hypoxic tumour microenvironments relative to normal tissue, preclinical/clinical trials, and future considerations. Conclusions: This review suggests that the four novel tumour hypoxia therapeutics demonstrate compelling evidence that these techniques can serve as powerful tools to increase targeting efficacy and radiosensitizing hypoxic tumour microenvironments relative to normal tissue. Each technique uses a different way to manipulate the therapeutic ratio, which we have labelled “oxygenate, target, use, and digest”. In addition, by focusing on emerging non-targeted and out-of-field effects, new umbrella targets are identified, which instead of sensitizing hypoxic cells, seek to reduce the radiosensitivity of normal tissues.

Methodological needs in the quality and safety characterisation of nanotechnology-based health products: Priorities for method development and standardisation

Nanotechnology-based health products are providing innovative solutions in health technologies and the pharmaceutical field, responding to unmet clinical needs. However, suitable standardised methods need to be available for quality and safety assessments of these innovative products prior to their translation into the clinic and for monitoring their performance when manufacturing processes are changed. The question arises which technological solutions are currently available within the scientific community to support the requested characterisation of nanotechnology-based products, and which methodological developments should be prioritized to support product developers in their regulatory assessment. To this end, the work presented here explored the state-of-the-art methods to identify methodological gaps associated with the preclinical characterisation of nanotechnology-based medicinal products and medical devices. The regulatory information needs, as expressed by regulatory authorities, were extracted from the guidance documents released so far for nanotechnology-based health products and mapped against available methods, thus allowing an analysis of methodological gaps and needs. In the first step, only standardised methods were considered, leading to the identification of methodological needs in five areas of characterisation, including: (i) surface properties, (ii) drug loading and release, (iii) kinetic properties in complex biological media, (iv) ADME (absorption, distribution, metabolism and excretion) parameters and (v) interaction with blood and the immune system. In the second step, a detailed gap analysis included analytical approaches in earlier stages of development, and standardised test methods from outside of the nanotechnology field that could address the identified areas of gaps. Based on this analysis, three categories of methodological needs were identified, including (i) method optimisation/adaptation to nanotechnological platforms, (ii) method validation/standardisation and (iii) method development for those areas where no technological solutions currently exist. The results of the analysis presented in this work should raise awareness within the scientific community on existing and emerging methodological needs, setting priorities for the development and standardisation of relevant analytical and toxicological methods allowing the development of a robust testing strategy for nanotechnology-based health products.

Gold Nanoclusters Display Low Immunogenic Effect in Microglia Cells

Gold nanoparticles hold a great promise for both clinical and preclinical applications. The major factors impeding such applications are toxicity of new nanomaterials including e.g., pro-apoptotic activities or inflammatory effects, but also their potential to accumulate in the body or inadequate absorption, distribution, metabolism and excretion (ADME) profiles. Since such adverse effects depend on the size, form and coating of nanomaterials, the search for new, less toxic nanomaterials with low tendency to accumulate is highly active domain of research. Here, we describe optical and biological properties of Au18 gold nanoclusters (NCs), small gold nanoparticles composed of 18 atoms of gold and stabilized with glutathione ligands. These nanoclusters may be suitable for in vivo applications owing to their low toxicity and biodistribution profile. Specifically, using lactate dehydrogenase (LDH) test in P19 cell line we found that Au18 NCs display low toxicity in vitro. Importantly, using primary microglial cells we showed that at low concentrations Au18 NCs display anti-inflammatory signaling on evidence of reduced interleukin 1-β (IL1-β) levels and unchanged levels of tumor necrosis factor (TNF-α) or Ym1/2. Such effect was dose dependent as higher concentrations of Au18 NCs induced expression of pro-inflammatory cytokines and suppression of anti-inflammatory cytokine Ym1/2, pointing, thus, to global inflammatory activity. Finally, we also showed that within 3 days Au18 NCs can be completely eliminated from the liver reported as the major target organ for accumulation of gold nanoparticles. These data point to a potential of gold nanoparticles for further biomedical studies.

Neuroinflammatory Regulation of Gold Nanoparticles Conjugated to Ethylene Dicysteine Diethyl Ester in Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a demyelinating chronic autoimmune inflammatory disease of the central nervous system (CNS). A large amount of proinflammatory cytokines is released in the CNS from the self-reactive T cells infiltrate, leading to the destruction of the myelin sheath and contributing to the development of MS. Several drugs have emerged in recent years to treat MS, and studies have shown that gold nanoparticles (GNPs) have anti-inflammatory properties in autoimmune diseases. Thus, the effects of GNP conjugation to ethylene dicysteine diethyl ester (ECD) were evaluated in C57BL/6 female mice exposed to experimental MS. Animals were exposed to experimental autoimmune encephalitis (EAE) induced by myelin oligodendrocyte glycoprotein (MOG35-55) in complete Freund's adjuvant supplemented with Mycobacterium tuberculosis. The clinical and cerebral effects of the different doses of ECD-GNPs (0.3, 0.6, and 1.0 mg/kg) were first studied, and the results showed that the group treated with 0.6 mg/kg ECD-GNPs improved clinical symptoms, inflammatory infiltrate, and myelin integrity. In the following step, GNPs and ECD-GNPs (0.6 mg/kg) showed improvements in the clinical signs of the disease. Moreover, there was a reduction in the levels of proinflammatory cytokines in both groups compared to EAE, and only the isolated use of GNPs increased IL-4 expression. Both NF-κB and TGFβ immunoexpression were significantly reduced following EAE + GNPs and EAE + ECD-GNPs treatment. In conclusion, GNPs and ECD-GNPs at 0.6 mg/kg attenuate the neurological signs of EAE likely due to inhibition of neuroinflammation induced by EAE.

Therapeutic enhancement of radiation and immunomodulation by gold nanoparticles in triple negative breast cancer

Gold nanoparticles (AuNPs) have been shown to enhance cancer radiotherapy (RT) gain by localizing the absorption of radiation energy in the tumor while sparing surrounding normal tissue from radiation toxicity. Previously, we showed that AuNPs enhanced RT induced DNA damage and cytotoxicity in MCF7 breast cancer cells. Interestingly, we found that cancer cells exhibited a size-dependent AuNPs intracellular localization (4 nm preferentially in the cytoplasm and 14 nm in the nucleus). We extended those studies to an in vivo model and examined the AuNPs effects on RT cytotoxicity, survival and immunomodulation of tumor microenvironment (TME) in human triple negative breast cancer (TNBC) xenograft mouse model. We also explored the significance of nanoparticle size in these AuNPs’ effects. Mice treated with RT and RT plus 4 nm or 14 nm AuNPs showed a significant tumor growth delay, compared to untreated animals, while dual RT plus AuNPs treatment exhibited additive effect compared to either RT or AuNPs treatment alone. Survival log-rank test showed significant RT enhancement with 14 nm AuNP alone; however, 4 nm AuNPs did not exhibit RT enhancement. Both sizes of AuNPs enhanced RT induced immunogenic cell death (ICD) that was coupled with significant macrophage infiltration in mice pretreated with 14 nm AuNPs. These results showing significant AuNP size-dependent RT enhancement, as evident by both tumor growth delay and overall survival, reveal additional underlying immunological mechanisms and provide a platform for studying RT multimodal approaches for TNBC that may be combined with immunotherapies, enhancing their effect.

Ultrastable PEGylated Calixarene-Coated Gold Nanoparticles with a Tunable Bioconjugation Density for Biosensing Applications

Many in vivo and in vitro applications using gold nanoparticles (AuNPs) require (i) their PEGylation, as it increases their stability and prevents nonspecific protein adsorption, and (ii) their conjugation to biomolecules, that provides them with specific recognition properties. Currently, the functionalization of AuNPs is based on thiol chemistry that suffers from two major drawbacks: (i) the Au-S bond is labile and confers limited chemical robustness to the organic layer, and (ii) control over the bioconjugation density is highly challenging. We report here a novel functionalization strategy based on calix[4]arene-tetradiazonium platforms for the coating of AuNPs with a robust PEG layer and their controlled bioconjugation. AuNPs were first modified with a functional calix[4]arene-diazonium salt bearing three PEG chains ended by a methoxy group and one by a carboxyl group. The resulting particles showed excellent chemical and colloidal stabilities, compared to similar systems obtained via a classical thiol chemistry, and could even be dispersed in human serum without degrading or aggregating. In addition to that, the carboxyl groups protruding from the PEG layer allowed their conjugation via amide bond formation with amine-containing biomolecules such as peptides. The control of the bioconjugation was obtained by grafting mixed layers of functional and nonfunctional PEGylated calix[4]arenes, that allowed varying the number of functional groups carried by the AuNPs and subsequently their bioconjugation capacity while preserving their dense protective PEG shell. Finally, we used these nanomaterials, modified with peptide aptamers, for the in vitro biosensing of a cancer biomarker, Mdm2.

Gold Nanoparticles as Radiosensitizers in Cancer Radiotherapy

The rapid development of nanotechnology offers a variety of potential therapeutic strategies for cancer treatment. High atomic element nanomaterials are often utilized as radiosensitizers due to their unique photoelectric decay characteristics. Among them, gold nanoparticles (GNPs) are one of the most widely investigated and are considered to be an ideal radiosensitizers for radiotherapy due to their high X-ray absorption and unique physicochemical properties. Over the last few decades, multi-disciplinary studies have focused on the design and optimization of GNPs to achieve greater dosing capability and higher therapeutic effects and highlight potential mechanisms for radiosensitization of GNPs. Although the radiosensitizing potential of GNPs has been widely recognized, its clinical translation still faces many challenges. This review analyses the different roles of GNPs as radiosensitizers in cancer radiotherapy and summarizes recent advances. In addition, the underlying mechanisms of GNP radiosensitization, including physical, chemical and biological mechanisms are discussed, which may provide new directions for the optimization and clinical transformation of next-generation GNPs.

Rac1: A potential radiosensitization target of human nasopharyngeal carcinoma CNE2 cells

Radiotherapy has a high cure rate for early nasopharyngeal carcinoma(NPC). However, the radiation resistance of poorly differentiated NPC cells impacts the effectiveness of treatment of early-stage NPC patients. Here, we explored the relationship between Ras-related C3 botulinum toxin substrate 1(Rac1) expression and NPC radiosensitivity. In vitro and in vivo studies revealed that upregulation of Rac1, when combined with X-ray treatment, increased growth inhibition and induced remarkable morphological changes and apoptosis in CNE2 cells. Furthermore, rupturing of the cell and nuclear membranes, degeneration of the cristae and significant swelling of the mitochondria were observed, which were consistent with the high apoptotic rate. The Rac1(+) cells exhibited approximately 50% more migration compared with that of the NC and Rac1(-) cells. The overexpression of Rac1 can increase the radiation sensitivity of NPC CNE2 cells, and the mechanism may be closely related to the oxidative damage of mitochondria. Rac1 might be a potential target for radiosensitization in poorly differentiated NPC.

Gold Nanoparticles as a Potent Radiosensitizer: A Transdisciplinary Approach from Physics to Patient

Over the last decade, a growing interest in the improvement of radiation therapies has led to the development of gold-based nanomaterials as radiosensitizer. Although the radiosensitization effect was initially attributed to a dose enhancement mechanism, an increasing number of studies challenge this mechanistic hypothesis and evidence the importance of chemical and biological contributions. Despite extensive experimental validation, the debate regarding the mechanism(s) of gold nanoparticle radiosensitization is limiting its clinical translation. This article reviews the current state of knowledge by addressing how gold nanoparticles exert their radiosensitizing effects from a transdisciplinary perspective. We also discuss the current and future challenges to go towards a successful clinical translation of this promising therapeutic approach.

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.

Recent advances in combinatorial cancer therapy via multifunctionalized gold nanoparticles

The diverse behavior of nanogold in the therapeutic field is related to its unique size and shape. Nanogold offers improvements in modern diagnostic and therapeutic implications, increases disease specificity and targeted drug delivery, and is relatively economical compared with other chemotherapeutic protocols. The diagnosis of cancer and photothermal therapy improve drastically with the implementation of nanotechnology. Different types of nanoparticles, that is, gold silica nanoshells, nanorods and nanospheres of diverse shapes and geometries, are used widely in the photothermal therapy of cancerous cells and nodules. Numerous reviews have been published on the therapeutic applications of gold nanoparticles, but studies on combinatorial applications of nanogold in cancer therapy are limited. This review focuses on the combinatorial cancer therapy using optical properties of nanogold with different shapes and geometries, and their therapeutic applications in cancer diagnosis, photothermal therapy, cancer imaging and targeted drug delivery.

Glioblastoma multiforme: a glance at advanced therapies based on nanotechnology

Glioblastoma multiforme (GBM, grade IV) is the most common malignant and invasive central nervous system tumor with poor survival outcome. Various pathogenesis signatures such as genetic mutation, hypoxia, necrosis and neo-angiogenesis are involved in GBM. Standard treatment includes surgical resection along with radiation therapy and temozolomide (TMZ) chemotherapy that do not improve the overall survival of patients. In this review, we focused on the diagnosis, risk factors and novel therapies, using advanced therapies such as nanotechnology in drug delivery, gene therapy and hyperthermia that have promising roles in the treatment of aggressive brain tumors.

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

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

Enhancement of Radiosensitization by Silver Nanoparticles Functionalized with Polyethylene Glycol and Aptamer As1411 for Glioma Irradiation Therapy

Background

The efficacy of radiotherapy for glioma is often limited by the radioresistance of glioma cells. The radiosensitizing effects of silver nanoparticles (AgNPs) on glioma were found in the previous studies of our group. In order to enhance the radiosensitivity of tumor cells and selectively kill them while reducing the side effects of irradiation therapy, targeted modification of AgNPs is urgently needed.

Materials and methods

In the present study, AgNPs functionalized with polyethylene glycol (PEG) and aptamer As1411 (AsNPs) were synthesized and subsequently characterized by transmission electron microscopy, ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy. Then the targeting property of AsNPs was evaluated by dark-field imaging, confocal microscopy and in vivo imaging. Both colony formation assay and glioma-bearing mouse model were employed to study the radiosensitizing effect of AsNPs.

Results

The characterization results revealed a spherical shape of AgNPs with an average diameter of 18 nm and the successful construction of AsNPs. AsNPs were confirmed to specifically target C6 glioma cells, but not normal human microvascular endothelial cells. Moreover, AsNPs could not only internalize into tumor cells, but also penetrate into the core of tumor spheroids. In vitro experiments showed that AsNPs exhibited a better radiosensitizing effect than AgNPs and PEGylated AgNPs (PNPs), inducing a higher rate of apoptotic cell death. In vivo imaging demonstrated that Cy5-AsNPs preferentially accumulated at the tumor site, and the ratio of fluorescence intensity of Cy5-AsNPs to that of Cy5-PNPs reached the maximum at 6 h post-systemic administration. Furthermore, the combination of AsNPs with irradiation significantly prolonged the median survival time of C6 glioma-bearing mice.

Conclusion

Our results indicated that AsNPs could be an effective nano-radiosensitizer for glioma targeting treatment.

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

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

Combined Effects of Gold Nanoparticles and Ionizing Radiation on Human Prostate and Lung Cancer Cell Migration

The effect of 15 nm-sized gold nanoparticles (AuNPs) and/or ionizing radiation (IR) on the migration and adhesion of human prostate (DU145) and lung (A549) cancer cell lines was investigated. Cell migration was measured by observing the closing of a gap created by a pipette tip on cell monolayers grown in 6-well plates. The ratio of the gap areas at 0 h and 24 h were used to calculate the relative migration. The relative migration of cells irradiated with 5 Gy was found to be 89% and 86% for DU145 and A549 cells respectively. When the cells were treated with 1 mM AuNPs this fell to ~75% for both cell lines. However, when the cells were treated with both AuNPs and IR an additive effect was seen, as the relative migration rate fell to ~60%. Of interest was that when the cells were exposed to either 2 or 5 Gy IR, their ability to adhere to the surface of a polystyrene culture plate was significantly enhanced, unlike that seen for AuNPs. The delays in gap filling (cell migration) in cells treated with IR and/or AuNPs can be attributed to cellular changes which also may have altered cell motility. In addition, changes in the cytoskeleton of the cancer cells may have also affected adhesiveness and thus the cancer cell's motility response to IR.

Backscattered electron emission after proton impact on gold nanoparticles with and without polymer shell coating

This work aims at measuring experimentally proton induced secondary electron energy spectra after interaction with gold nano particles (GNPs) and polymer-coated GNPs. Backscattered electron energy spectra were collected over a 0 to 1000 eV energy range using a retarding field analyzer (RFA). This paper presents the spectra obtained for proton beam energies of 0.5 and 2 MeV and diameter 2.5 and 3.8 nm GNPs. The spectra were also measured for 3.8 nm GNPs after 5 and 10 MeV proton irradiations. GNPs were deposited on a 100 nm carbon film. Each experimental spectrum was compared with dedicated simulations based on existing numerical models used in the TRAX and Geant4 Monte Carlo codes. For 100 nm carbon target, good agreement between experimental, TRAX and Geant4 simulation results can be observed. For 3.8 nm GNPs, the TRAX simulations reproduce with good agreement the electron energy spectra produced after 0.5, 2, 5 and 10 MeV proton irradiations, while Geant4 spectra display a lower secondary electron yield at low energy (<600 eV) for all the studied energies. This underestimation can mostly be explained by the 790 eV threshold applied in the condensed history model used by Geant4 which impacts the secondary electron energy distribution. Results obtained for carbon and gold targets highlight the impact of the secondary electron production threshold for proton ionization process considered in condensed history models. The experimental results demonstrate that the single interaction approach used in TRAX is adapted to reproduce secondary electron emission from GNPs. On the other hand, the standard electron generation threshold implement in G4BetheBlochModel and G4BraggModel condensed-history models used in Geant4 is not adapted to reproduce low energy electron emission in gold targets. Finally, the results highlight that the GNP coating leads to a decrease of the electron yield and mostly affects low energy electrons (<500 eV) emitted from GNPs.

Prediction of Gold Nanoparticle and Microwave-Induced Hyperthermia Effects on Tumor Control via a Simulation Approach

Hyperthermia acts as a powerful adjuvant to radiation therapy and chemotherapy. Recent advances show that gold nanoparticles (Au-NPs) can mediate highly localized thermal effects upon interaction with laser radiation. The purpose of the present study was to investigate via in silico simulations the mechanisms of Au-NPs and microwave-induced hyperthermia, in correlation to predictions of tumor control (biological endpoints: tumor shrinkage and cell death) after hyperthermia treatment. We also study in detail the dependence of the size, shape and structure of the gold nanoparticles on their absorption efficiency, and provide general guidelines on how one could modify the absorption spectrum of the nanoparticles in order to meet the needs of specific applications. We calculated the hyperthermia effect using two types of Au-NPs and two types of spherical tumors (prostate and melanoma) with a radius of 3 mm. The plasmon peak for the 30 nm Si-core Au-coated NPs and the 20 nm Au-NPs was found at 590 nm and 540 nm, respectively. Considering the plasmon peaks and the distribution of NPs in the tumor tissue, the induced thermal profile was estimated for different intervals of time. Predictions of hyperthermic cell death were performed by adopting a three-state mathematical model, where “three-state” includes (i) alive, (ii) vulnerable, and (iii) dead states of the cell, and it was coupled with a tumor growth model. Our proposed methodology and preliminary results could be considered as a proof-of-principle for the significance of simulating accurately the hyperthermia-based tumor control involving the immune system. We also propose a method for the optimization of treatment by overcoming thermoresistance by biological means and specifically through the targeting of the heat shock protein 90 (HSP90), which plays a critical role in the thermotolerance of cells and tissues.

Photothermal cancer immunotherapy by erythrocyte membrane-coated black phosphorus formulation

Basal-like breast cancer exhibits a triple-negative phenotype and has a poor prognosis, even with traditional chemical and anti-human epidermal growth factor receptor (HER) treatments. However, the high mutation rate of this obstinate cancer type renders it suitable for immunotherapy. Photothermal therapy (PTT) is a high-efficiency method for inducing tumor neoantigen release in situ, which has great potential for use in cancer immunotherapy. Here, we prepared a biomimetic black phosphorus quantum dot (BPQDs) formulation to induce breast cancer cell apoptosis in situ by near-infrared (NIR) laser irradiation to mobilize the immune system to eliminate the residual and metastatic cancer cells. Erythrocyte membranes (RMs) were used to coat the BPQDs, forming a BPQD-RM nanovesicle (BPQD-RMNV) biomimetic formulation that exhibited a long circulation time and tumor accumulation in vivo. The basal-like 4T1 breast tumor underwent apoptosis and necrosis with the irradiation and recruited dendritic cells (DCs) to capture the tumor antigens in vivo. Furthermore, programmed cell death protein 1 (PD-1) antibody (aPD-1) was employed to prevent the CD8⁺ T cells from exhaustion. Notably, BPQD-RMNV-mediated PTT combined with aPD-1 treatment significantly delayed residual and metastatic tumor growth in vivo. Hence, BPQD-RMNV-mediated PTT combined with immune checkpoint blockade antibody increased the infiltration and activity of CD8⁺ T cells in the tumor, which directly restrained basal-like breast tumor growth in vivo.

Remote Trice Light, Temperature, and pH-actuation of Switchable Magneto-Plasmonic Nanocarriers for Combinational Photothermal and Controlled/Targeted Chemotherapies

Three magneto-plasmonic nanohybrids were synthesized using Au- and Ag-coated Fe₃O₄ nanoparticles (NPs)-modified dual pH- and temperature-responsive triblock copolymer of poly (butyl methacrylate-co-acrylamide-co-methacrylic acid) to serve as drug carriers with potential of using in both photothermal and controlled/targeted chemotherapies. The internal superparamagnetic core gives the carriers targeted-delivery characteristics, and surface plasmon resonance-based noble metallic Au/Ag shells give them on-demand photothermal and photo-triggering release properties. To investigate the effect of coating method on the targeting property of synthesized carriers, Au NPs were attached to the magnetic core by 2 different direct/indirect procedures and the properties of the synthesized carriers including swelling ratio and thermal and optical sensitivity and switching were comprehensively investigated in 2 different buffer solutions with pH 5.5 and 7.4 at 37°C. Letrozole was used as a model anticancer drug and its loading and release properties were evaluated for the four nanocarriers. The cytotoxicity of drug-free and letrozole-loaded nanocarriers on normal L929 fibroblast and MDAMB 231 breast cancer cell lines was evaluated in absence/presence of laser radiation. The results revealed that the carriers have the potential of serving as switchable trimodal light/temperature/pH-triggered and targeted/controlled drug delivery platforms for chemophotothermal therapy.

Gold nanorods together with HSP inhibitor-VER-155008 micelles for colon cancer mild-temperature photothermal therapy

Enhancing the heat-sensitivity of tumor cells provides an alternative solution to maintaining the therapeutic outcome of photothermal therapy (PTT). In this study, we constructed a therapeutic system, which was composed of methoxy-polyethylene-glycol-coated-gold-nanorods (MPEG-AuNR) and VER-155008-micelles, to evaluate the effect of VER-155008 on the sensitivity of tumor cells to heat, and further investigate the therapeutic outcome of MPEG-AuNR mediated PTT combined with VER-155008- micelles. VER-155008- micelles down-regulate the expression of heat shock proteins and attenuate the heat-resistance of tumor cell. The survival of HCT116 cells treated with VER-155008- micelles under 45 °C is equal to that treated with high temperature hyperthermia (55 °C) in vitro. Furthermore, we proved either the MPEG-AuNR or VER-155008- micelles can be accumulate in the tumor site by photoacoustic imaging and fluorescent imaging. In vivo anti-cancer evaluation showed that tumor size remarkably decreased (smaller than 100 mm³ or vanished) when treated with combing 45 °C mild PTT system, which contrasted to the tumor size when treated with individual 45 °C mild PTT (around 500 nm³) or normal saline as control (larger than 2000 nm³). These results proved that the VER-155008- micelles can attenuate the heat-resistance of tumor cells and enhance the therapeutic outcome of mild-temperature photothermal therapy.

Structural organization of lipid-functionalized-Au nanoparticles

Gold nanoparticles (AuNPs) are considered suitable systems for drug delivery and diagnostics with several applications in biomedicine. Size, shape and surface functionalization of these nanoparticles are important parameters influencing their behavior in a biological environment. This study describes the preparation and the characterization of lysophosphocholine coated AuNPs by means of Small Angle Neutron Scattering (SANS), Electron Paramagnetic Resonance (EPR) and Fluorescence Spectroscopy. In particular the structure of the functionalized AuNP suspension, as well as the physical properties, of the nanoparticle organic coating are discussed. The experimental results indicated that functionalized lysophosphocholine-AuNPs form aggregates, which are composed by nanoparticles with core-shell structure. Nevertheless, the nanoparticle suspension resulted to be stable, without significant structural rearrangements even when the temperature was increased to 50 °C. At the same time, experimental evidences also suggested that the 18LPC layer around AuNPs presented a reduced chain packing compared to pure 18LPC aggregates.

Combining photothermal therapy and immunotherapy against melanoma by polydopamine-coated Al2O3 nanoparticles

Photothermal therapy (PTT) can be an effective antitumor therapy, but it may not completely eliminate tumor cells, leading to the risk of recurrence or metastasis. Here we describe nanocarriers that allow combination therapy involving PTT and immunotherapy. Nanocarriers are prepared by coating Al₂O₃ nanoparticles with non-toxic, biodegradable polydopamine, which shows high photothermal efficiency. A near-infrared laser irradiation can kill the majority of tumor tissues, resulting in the release of tumor-associated antigens. The Al₂O₃ within the nanoparticles, together with CpG, acts as an adjuvant to trigger robust cell-mediated immune responses that can help eliminate the residual tumor cells and reduce the risk of tumor recurrence.

Methods: The characteristics and photothermal performance of polydopamine-coated Al₂O₃ nanoparticles were examined after one-step preparation. Then we studied their internalization, photothermal toxicity and immunostimulatory activity in vitro. For in vivo experiments, these nanocarriers were injected directly into B16F10 melanoma allografts in mice to ensure specific localization. After photothermal irradiation on day 0, mice were subcutaneously injected with CpG adjuvant on day 1, 3 and 5. Tumor volumes and number of living mice were recorded every two days. Moreover, various immune responses induced by our combined therapy were tested for mechanism research.

Results: 50% of mice after our combined treatment successfully achieved the goal of tumor eradication, and survived for 120 days, which was the end point of the experiment. Mechanism studies demonstrated the combined therapy efficiently led to dendritic cell maturation, resulting in the secretion of antibodies and cytokines as well as the proliferation of splenocytes and lymphocytes for anti-tumor immunotherapy.

Conclusion: Taken together, these results demonstrated the promise of our combined photothermal therapy and immunotherapy for tumor shrinkage, which merited further research.

Metal-based NanoEnhancers for Future Radiotherapy: Radiosensitizing and Synergistic Effects on Tumor Cells

Radiotherapy is one of the major therapeutic strategies for cancer treatment. In the past decade, there has been growing interest in using high Z (atomic number) elements (materials) as radiosensitizers. New strategies in nanomedicine could help to improve cancer diagnosis and therapy at cellular and molecular levels. Metal-based nanoparticles usually exhibit chemical inertness in cellular and subcellular systems and may play a role in radiosensitization and synergistic cell-killing effects for radiation therapy. This review summarizes the efficacy of metal-based NanoEnhancers against cancers in both in vitro and in vivo systems for a range of ionizing radiations including gamma-rays, X-rays, and charged particles. The potential of translating preclinical studies on metal-based nanoparticles-enhanced radiation therapy into clinical practice is also discussed using examples of several metal-based NanoEnhancers (such as CYT-6091, AGuIX, and NBTXR3). Also, a few general examples of theranostic multimetallic nanocomposites are presented, and the related biological mechanisms are discussed.

Recent Advances in Cancer Therapy Based on Dual Mode Gold Nanoparticles

Many tumor-targeted strategies have been used worldwide to limit the side effects and improve the effectiveness of therapies, such as chemotherapy, radiotherapy (RT), etc. Biophotonic therapy modalities comprise very promising alternative techniques for cancer treatment with minimal invasiveness and side-effects. These modalities use light e.g., laser irradiation in an extracorporeal or intravenous mode to activate photosensitizer agents with selectivity in the target tissue. Photothermal therapy (PTT) is a minimally invasive technique for cancer treatment which uses laser-activated photoabsorbers to convert photon energy into heat sufficient to induce cells destruction via apoptosis, necroptosis and/or necrosis. During the last decade, PTT has attracted an increased interest since the therapy can be combined with customized functionalized nanoparticles (NPs). Recent advances in nanotechnology have given rise to generation of various types of NPs, like gold NPs (AuNPs), designed to act both as radiosensitizers and photothermal sensitizing agents due to their unique optical and electrical properties i.e., functioning in dual mode. Functionalized AuNPS can be employed in combination with non-ionizing and ionizing radiation to significantly improve the efficacy of cancer treatment while at the same time sparing normal tissues. Here, we first provide an overview of the use of NPs for cancer therapy. Then we review many recent advances on the use of gold NPs in PTT, RT and PTT/RT based on different types of AuNPs, irradiation conditions and protocols. We refer to the interaction mechanisms of AuNPs with cancer cells via the effects of non-ionizing and ionizing radiations and we provide recent existing experimental data as a baseline for the design of optimized protocols in PTT, RT and PTT/RT combined treatment.

Particle therapy and nanomedicine: state of art and research perspectives

Cancer radiation therapy with charged particle beams, called particle therapy, is a new therapeutic treatment presenting major advantages when compared to conventional radiotherapy. Because ions have specific ballistic properties and a higher biological effectiveness, they are superior to x-rays. Numerous medical centres are starting in the world using mostly protons but also carbon ions as medical beams. Several investigations are attempting to reduce the cost/benefit ratio and enlarge the range of therapeutic indications. A major limitation of particle therapy is the presence of low but significant damage induced in healthy tissues located at the entrance of the ion track prior to reaching the tumour. It is thus a major challenge to improve the targeting of the tumours, concentrating radiation effects in the malignance. A novel strategy, based on the addition of nanoparticles targeting the tumour, was suggested over a decade ago to improve the performance of conventional photon therapy. Recently, similar developments have emerged for particle therapy and the amount of research is now exploding. In this paper, we review the experimental results, as well as theoretical and simulation studies that shed light in the promising outcomes of this strategy and in the underpinning mechanisms. Several experiments provide consistent evidence of significant enhancement of ion radiation effects in the presence of nanoparticles. In view of implementing this strategy for cancer treatment, simulation studies have begun to establish the rationale and the specificity of this effect. In addition, these studies will help to outline a list of possible mechanisms and to predict the impact of ion beams and nanoparticle characteristics. Many questions remain unsolved, but the findings of these first studies are encouraging and open new challenges. After summarizing the main results in the field, we propose a roadmap to pursue future research with the aim to strengthen the potential interplay between particle therapy and nanomedicine.

Recent advances in nanomedicine and survivin targeting in brain cancers

Brain cancer is a highly lethal disease, especially devastating toward both the elderly and children. This cancer has no therapeutics available to combat it, predominately due to the blood-brain barrier (BBB) preventing treatments from maintaining therapeutic levels within the brain. Recently, nanoparticle technology has entered the forefront of cancer therapy due to its ability to deliver therapeutic effects while potentially passing physiological barriers. Key nanoparticles for brain cancer treatment include glutathione targeted PEGylated liposomes, gold nanoparticles, superparamagnetic iron oxide nanoparticles and nanoparticle-albumin bound drugs, with these being discussed throughout this review. Recently, the survivin protein has gained attention as it is over-expressed in a majority of tumors. This review will briefly discuss the properties of survivin, while focusing on how both nanoparticles and survivin-targeting treatments hold potential as brain cancer therapies. This review may provide useful insight into new brain cancer treatment options, particularly survivin inhibition and nanomedicine.