Fluorescent Radiosensitizing Gold Nanoparticles

In Vitro and In Vivo Synergetic Radiotherapy with Gold Nanoparticles and Docetaxel for Pancreatic Cancer

This research underscores the potential of combining nanotechnology with conventional therapies in cancer treatment, particularly for challenging cases like pancreatic cancer. We aimed to enhance pancreatic cancer treatment by investigating the synergistic effects of gold nanoparticles (GNPs) and docetaxel (DTX) as potential radiosensitizers in radiotherapy (RT) both in vitro and in vivo, utilizing a MIA PaCa-2 monoculture spheroid model and NRG mice subcutaneously implanted with MIA PaCa-2 cells, respectively. Spheroids were treated with GNPs (7.5 μg/mL), DTX (100 nM), and 2 Gy of RT using a 6 MV linear accelerator. In parallel, mice received treatments of GNPs (2 mg/kg), DTX (6 mg/kg), and 5 Gy of RT (6 MV linear accelerator). In vitro results showed that though RT and DTX reduced spheroid size and increased DNA DSBs, the triple combination of DTX/RT/GNPs led to a significant 48% (p = 0.05) decrease in spheroid size and a 45% (p = 0.05) increase in DNA DSBs. In vivo results showed a 20% (p = 0.05) reduction in tumor growth 20 days post-treatment with (GNPs/RT/DTX) and an increase in mice median survival. The triple combination exhibited a synergistic effect, enhancing anticancer efficacy beyond individual treatments, and thus could be employed to improve radiotherapy and potentially reduce adverse effects.

An Insight Into the Physicochemical Properties of Gold Nanoparticles in Relation to Their Clinical and Diagnostic Applications

The ease of formulation and surface modification of gold nanoparticles (AuNPs) by ligands, greater biocompatibility, non-cytotoxicity, and excellent optical properties are the characteristics that necessitate their application in clinical and genomic research. Not only that, but the extensive synthetic chemistry of AuNPs also offers precise control over physicochemical and optical properties owing to the inert, biocompatible, and non-toxic nature of the inner gold core. Another important property of AuNPs involves their incorporation into larger structures, including liposomes or polymeric materials, thereby increasing their capability of drug delivery in concurrent therapy and imaging labels for enhanced diagnostic applications. AuNPs are endowed with physical properties that suggest their use as adjuvants for radiotherapy and bio-imaging and in computed tomography (CT) scans, diagnostic systems, and therapy. Thus, these features strongly endorse the AuNPs in thrust areas of biomedical fields. The diverse properties of gold nanoparticles (AuNPs) have made them promising candidates in biomedical fields, including in the development of theranostics, which encompasses using these gold nanoparticles for both diagnosis and therapy simultaneously. To appreciate these and related applications, a need arises to review the basic principles and multifunctional attributes of AuNPs in relation to their advances in imaging, therapy, and diagnostics.

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

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

Aptamer-conjugated gold nanoparticles and their diagnostic and therapeutic roles in cancer

The burden of incidence rate and mortality of cancer is increasing rapidly, and the development of precise intervention measures for cancer detection and treatment will help reduce the burden and pain of cancer. At present, the sensitivity and specificity of tumor markers such as CEA and CA-125 used clinically are low, while PET, SPECT, and other imaging diagnoses with high sensitivity possess shortcomings, including long durations to obtain formal reports and the inability to identify the molecular pathological type of cancer. Cancer surgery is limited by stage and easy to recur. Radiotherapy and chemotherapy often cause damage to normal tissues, leading to evident side effects. Aptamers can selectively and exclusively bind to biomarkers and have, therefore, gained attention as ligands to be targeted for cancer detection and treatment. Gold nanoparticles (AuNPs) are considered as promising nano carriers for cancer diagnosis and treatment due to their strong light scattering characteristics, effective biocompatibility, and easy surface modification with targeted agents. The aptamer-gold nanoparticles targeting delivery system developed herein can combine the advantages of aptamers and gold nanoparticles, and shows excellent targeting, high specificity, low immunogenicity, minor side effects, etc., which builds a bridge for cancer markers to be used in early and efficient diagnosis and precise treatment. In this review, we summarize the latest progress in the application of aptamer-modified gold nanoparticles in cancer targeted diagnosis and delivery of therapeutic agents to cancer cells and emphasize the prospects and challenges of transforming these studies into clinical applications.

Radiosensitization with Gadolinium Chelate-Coated Gold Nanoparticles Prevents Aggressiveness and Invasiveness in Glioblastoma

Purpose

This study aimed to evaluate the radiosensitizing potential of Au@DTDTPA(Gd) nanoparticles when combined with conventional external X-ray irradiation (RT) to treat GBM.

Methods

Complementary biological models based on U87 spheroids including conventional 3D invasion assay, organotypic brain slice cultures, chronic cranial window model were implemented to investigate the impact of RT treatments (10 Gy single dose; 5×2 Gy or 2×5 Gy) combined with Au@DTDTPA(Gd) nanoparticles on tumor progression. The main tumor mass and its infiltrative area were analyzed. This work focused on the invading cancer cells after irradiation and their viability, aggressiveness, and recurrence potential were assessed using mitotic catastrophe quantification, MMP secretion analysis and neurosphere assays, respectively.

Results

In vitro clonogenic assays showed that Au@DTDTPA(Gd) nanoparticles exerted a radiosensitizing effect on U87 cells, and in vivo experiments suggested a benefit of the combined treatment "RT 2×5 Gy + Au@DTDTPA(Gd)" compared to RT alone. Invasion assays revealed that invasion distance tended to increase after irradiation alone, while the combined treatments were able to significantly reduce tumor invasion. Monitoring of U87-GFP tumor progression using organotypic cultures or intracerebral grafts confirmed the anti-invasive effect of Au@DTDTPA(Gd) on irradiated spheroids. Most importantly, the combination of Au@DTDTPA(Gd) with irradiation drastically reduced the number, the viability and the aggressiveness of tumor cells able to escape from U87 spheroids. Notably, the combined treatments significantly reduced the proportion of escaped cells with stem-like features that could cause recurrence.

Conclusion

Combining Au@DTDTPA(Gd) nanoparticles and X-ray radiotherapy appears as an attractive therapeutic strategy to decrease number, viability and aggressiveness of tumor cells that escape and can invade the surrounding brain parenchyma. Hence, Au@DTDTPA(Gd)-enhanced radiotherapy opens up interesting perspectives for glioblastoma treatment.

High-Yield 99mTc Labeling of Gold Nanoparticles Carrying Atropine and Adrenaline

This work focuses on the synthesis, purification, and analytical characterization of novel multifunctional Au NPs radiolabeled with ^99mTc. These mixed-ligand shell Au NPs represent pharmacologically relevant samples for potential application in theragnostics. A ligand using a plain linker with a rather long chain consisting of 10 CH₂ groups and a thiol moiety along with the PADA chelator has been used for both the attachment to the Au NP surface and for the ^99mTc(CO)₃⁺ complexation. We have combined this with our approach of stabilizing Au NP without any PEG or other stabilizing groups. Thus, monoligand shell Au NPs were radiolabeled by different strategies (prelabeling and postlabeling). Additionally, pharmacologically relevant Au NPs were synthesized carrying both a biofunctionalization with either atropine or adrenaline and the ^99mTc radiolabel. All samples were obtained in very good yields (up to 80% of the total activity loaded onto the column) and completely/particularly purified using desalting columns. Detailed analytical characterization of the Au NPs before and after radiolabeling has proven the NPs' robustness throughout the process. Their intact functionalization, shape, and stability was confirmed by transmission electron microscopy (TEM), ultraviolet/visible (UV/vis) spectroscopy, dynamic light scattering (DLS), and infrared (IR) spectroscopy. The presented strategy represents a versatile building block system that can be adapted to a variety of bioactive molecules and may be of high relevance for theragnostic applications.

Carrier-Free Trehalose-Based Nanomotors Targeting Macrophages in Inflammatory Plaque for Treatment of Atherosclerosis

Inducing autophagy of macrophages to improve abnormal lipid metabolism is an important way to treat atherosclerosis (AS). Yet, the current application of the mammalian target of rapamycin (mTOR)-dependent autophagy inducers is limited by the side effects and lack of targeting and low biological availability. Herein, a kind of nitric oxide (NO)-driven carrier-free nanomotor based on the reaction between trehalose (Tr, one of the mTOR-independent autophagy inducers), L-arginine (Arg), and phosphatidylserine (PS) is reported. The developed nanomotors use NO as the driving force, which is generated from the reaction between Arg and excessive reactive oxygen species (ROS) and inducible nitric oxide synthase (iNOS) specifically presenting in the AS microenvironment. The high expression of ROS and iNOS in the AS site can be used as chemoattractants to induce chemotaxis behavior of the nanomotors to achieve the first-step targeting an AS plaque. Subsequently, the "eat me" signal sent by PS is exploited to precisely target to the macrophages in the AS plaque, realizing the plaque-macrophage-targeted effect by this step-by-step strategy. In vitro and in vivo results confirm that the introduction of the concept of carrier-free nanomotors has greatly improved the biological availability of trehalose (the dose can be reduced from 2.5 g kg^-1 in previous reports to 0.01 g kg^-1 in this work). Particularly, consumed ROS and the production of NO during the targeting process also play positive roles, in which the former regulates the M2 polarization of macrophages and the latter promotes the reconstruction of an endothelial barrier, which contributes to the multilink treatment of AS.

Magnetic Mesoporous Silica Nanorods Loaded with Ceria and Functionalized with Fluorophores for Multimodal Imaging

Multifunctional magnetic nanocomposites based on mesoporous silica have a wide range of potential applications in catalysis, biomedicine, or sensing. Such particles combine responsiveness to external magnetic fields with other functionalities endowed by the agents loaded inside the pores or conjugated to the particle surface. Different applications might benefit from specific particle morphologies. In the case of biomedical applications, mesoporous silica nanospheres have been extensively studied while nanorods, with a more challenging preparation, have attracted much less attention despite the positive impact on the therapeutic performance shown by seminal studies. Here, we report on a sol-gel synthesis of mesoporous rodlike silica particles of two distinct lengths (1.4 and 0.9 μm) and aspect ratios (4.7 and 2.2) using Pluronic P123 as a structure-directing template and rendering ∼1 g of rods per batch. Iron oxide nanoparticles have been synthesized within the pores yielding maghemite (γ-Fe₂O₃) nanocrystals of elongated shape (∼7 nm × 5 nm) with a [110] preferential orientation along the rod axis and a superparamagnetic character. The performance of the rods as T₂-weighted MRI contrast agents has also been confirmed. In a subsequent step, the mesoporous silica rods were loaded with a cerium compound and their surface was functionalized with fluorophores (fluorescamine and Cyanine5) emitting at λ = 525 and 730 nm, respectively, thus highlighting the possibility of multiple imaging modalities. The biocompatibility of the rods was evaluated in vitro in a zebrafish (Danio rerio) liver cell line (ZFL), with results showing that neither long nor short rods with magnetic particles caused cytotoxicity in ZFL cells for concentrations up to 50 μg/ml. We advocate that such nanocomposites can find applications in medical imaging and therapy, where the influence of shape on performance can be also assessed.

The Physical Chemistry and Chemical Physics (PCCP) Section of the International Journal of Molecular Sciences in Its Publications: The First 300 Thematic Articles in the First 3 Years

The Physical Chemistry and Chemical Physics Section (PCCP Section) is one of the youngest among the sections of the International Journal of Molecular Sciences (IJMS)-the year 2021 will only mark three years since its inception [...].

The detrimental invasiveness of glioma cells controlled by gadolinium chelate-coated gold nanoparticles

Glioblastoma are characterized by an invasive phenotype, which is thought to be responsible for recurrences and the short overall survival of patients. In the last decade, the promising potential of ultrasmall gadolinium chelate-coated gold nanoparticles (namely Au@DTDTPA(Gd)) was evidenced for image-guided radiotherapy in brain tumors. Considering the threat posed by invasiveness properties of glioma cells, we were interested in further investigating the biological effects of Au@DTDTPA(Gd) by examining their impact on GBM cell migration and invasion. In our work, exposure of U251 glioma cells to Au@DTDTPA(Gd) led to high accumulation of gold nanoparticles, that were mainly diffusely distributed in the cytoplasm of the tumor cells. Experiments pointed out a significant decrease in glioma cell invasiveness when exposed to nanoparticles. As the proteolysis activities were not directly affected by the intracytoplasmic accumulation of Au@DTDTPA(Gd), the anti-invasive effect cannot be attributed to matrix remodeling impairment. Rather, Au@DTDTPA(Gd) nanoparticles affected the intrinsic biomechanical properties of U251 glioma cells, such as cell stiffness, adhesion and generated traction forces, and significantly reduced the formation of protrusions, thus exerting an inhibitory effect on their migration capacities. Consistently, analysis of talin-1 expression and membrane expression of beta 1 integrin evoke the stabilization of focal adhesion plaques in the presence of nanoparticles. Taken together, our results highlight the interest in Au@DTDTPA(Gd) nanoparticles for the therapeutic management of astrocytic tumors, not only as a radio-enhancing agent but also by reducing the invasive potential of glioma cells.

A simple method to estimate the mean number of lipophilic molecules on nanoparticle surfaces by fluorescence measurements

Measurements of fluorescence intensity of the hydrophobic pyridinium salt (DTPSH) remaining in the organic phase after partition experiments in the DCM/H₂O system allowed an approximate method to be developed to estimate the mean number of molecules (N = 942) on the surface of 22.8 nm gold nanoparticles and the separation (1.89 nm) between these organic molecules. This protocol is based on the ability that the organic molecules possess to coat the surface of the nanoparticle, which can migrate from the organic to the aqueous phase as a result of the driving force of the strong binding of sulfur to gold. To validate our estimation, we used a projection of the results obtained by Wales and Ulker to solve the Thomson problem, a mathematicians' challenge, used as a model to calculate the mean distance (1.82 nm) separating particles on the surface, in excellent agreement with the results obtained by our method. The quality of results, the simplicity of calculations, the low fluorescence detection limit, and the inexpensive materials, recommend this procedure for rapid estimates of the mean number of molecules on the surface of nanoparticles.

Unexpected Function of a Heptapeptide-Conjugated Zwitterionic Polymer that Coassembles into β-Amyloid Fibrils and Eliminates the Amyloid Cytotoxicity

Fibrillogenesis of amyloid β-protein (Aβ) is pathologically associated with Alzheimer's disease (AD), so modulating Aβ aggregation is crucial for AD prevention and treatment. Herein, a zwitterionic polymer with short dimethyl side chains (pID) is synthesized and conjugated with a heptapeptide inhibitor (Ac-LVFFARK-NH₂, LK7) to construct zwitterionic polymer-inhibitor conjugates for enhanced inhibition of Aβ aggregation. However, it is unexpectedly found that the LK7@pID conjugates remarkably promote Aβ fibrillization to form more fibrils than the free Aβ system but effectively eliminate Aβ-induced cytotoxicity. Such an unusual behavior of the LK7@pID conjugates is unraveled by extensive mechanistic studies. First, the hydrophobic environment within the assembled micelles of LK7@pID promotes the hydrophobic interaction between Aβ molecules and LK7@pID, which triggers Aβ aggregation at the very beginning, making fibrillization occur at an earlier stage. Second, in the aggregation process, the LK7@pID micelles disassemble by the intensive interactions with Aβ, and LK7@pID participates in the fibrillization by being embedded in the Aβ fibrils, leading to the formation of hybrid and heterogeneous fibrillar aggregates with a different structure than normal Aβ fibrils. This unique Trojan horse-like feature of LK7@pID conjugates has not been observed for any other inhibitors reported previously and may shed light on the design of new modulators against β-amyloid cytotoxicity.

Application of Nanomaterials in Biomedical Imaging and Cancer Therapy

Nanomaterials, such as nanoparticles, nanorods, nanosphere, nanoshells, and nanostars, are very commonly used in biomedical imaging and cancer therapy. They make excellent drug carriers, imaging contrast agents, photothermal agents, photoacoustic agents, and radiation dose enhancers, among other applications. Recent advances in nanotechnology have led to the use of nanomaterials in many areas of functional imaging, cancer therapy, and synergistic combinational platforms. This review will systematically explore various applications of nanomaterials in biomedical imaging and cancer therapy. The medical imaging modalities include magnetic resonance imaging, computed tomography, positron emission tomography, single photon emission computerized tomography, optical imaging, ultrasound, and photoacoustic imaging. Various cancer therapeutic methods will also be included, including photothermal therapy, photodynamic therapy, chemotherapy, and immunotherapy. This review also covers theranostics, which use the same agent in diagnosis and therapy. This includes recent advances in multimodality imaging, image-guided therapy, and combination therapy. We found that the continuous advances of synthesis and design of novel nanomaterials will enhance the future development of medical imaging and cancer therapy. However, more resources should be available to examine side effects and cell toxicity when using nanomaterials in humans.

Increased carcinoembryonic antigen expression on the surface of lung cancer cells using gold nanoparticles during radiotherapy

PURPOSE

Tumor-associated antigens are a promising target of immunotherapy approaches for cancer treatments but rely on sufficient expression of the target antigen. This study investigates the expression of the carcinoembryonic antigen (CEA) on the surface of irradiated lung cancer cells in vitro using gold nanoparticles as radio-enhancer.

METHODS

Human lung carcinoma cells A549 were irradiated and expression of CEA on the cell surface measured by flow cytometry 3 h, 24 h, and 72 h after irradiation to doses of 2 Gy, 6 Gy, 10 Gy, and 20 Gy in the presence or absence of 0.1 mg/ml or 0.5 mg/ml gold nanoparticles. CEA expression was measured as median fluorescent intensity and percentage of CEA-positive cells.

RESULTS

An increase in CEA expression was observed with both increasing radiation dose and time. There was doubling in median fluorescent intensity 24 h after 20 Gy irradiation and 72 h after 6 Gy irradiation. Use of gold nanoparticles resulted in additional significant increase in CEA expression. Change in cell morphology included swelling of cells and increased internal complexity in accordance with change in CEA expression.

CONCLUSIONS

This study showed an increase in CEA expression on human lung carcinoma cells following irradiation. Increase in expression was observed with increasing radiation dose and in a time dependent manner up to 72 h post irradiation. The results further showed that gold nanoparticles can significantly increase CEA expression following radiotherapy.

Uptake and excretion dynamics of gold nanoparticles in cancer cells and fibroblasts

Radiotherapy is one of the main treatments used to fight cancer. A major limitation of this modality is the lack of selectivity between cancerous and healthy tissues. One of the most promising strategies proposed in this last decade is the addition of nanoparticles with high-atomic number to enhance radiation effects in tumors. Gold nanoparticles (AuNPs) are considered as one of the best candidates because of their high radioenhancing property, simple synthesis and low toxicity. Ultra small AuNPs (core size of 2.4 nm and hydrodynamic diameter of 4.5 nm) covered with dithiolated diethylenetriaminepentaacetic acid (Au@DTDTPA) are of high interest because of their properties to bind MRI active or PET active compounds at their surface, to concentrate in some tumors and be eliminated via renal clearance thanks to their small size. These key figures make Au@DTDTPA the best candidate to develop image-guided radiotherapy. Surprisingly the capacity of the nanoparticles to penetrate cells, an important issue to predict radioenhancement, has not been established yet. Here, we report the uptake dynamics, internalization routes and excretion dynamics of Au@DTDTPA nanoparticles in various cancer cell lines including glioblastoma (U87-MG), chordoma (UM-Chor1), cervix (HeLa), prostate (PC3), and pancreatic (BxPC-3) cell lines as well as fibroblasts (Dermal fibroblasts). This study demonstrates a strong cell line dependence of the nanoparticle uptake and excretion dynamics. Different pathways of cell internalization evidenced here explain this dependence. As a major finding, the retention of Au@DTDTPA nanoparticles was found to be higher in cancer cells than in fibroblasts. This result strengthens the strategy of using nanoagents to improve tumor selectivity of radiation treatments. In particular Au@DTDTPA nanoparticles are good candidates to improve the treatment of radioresitant gliobastoma, pancreatic and prostate cancer in particular. In conclusion, the variability of cell-to-nanoparticle interaction is a new parameter to consider in the choice of nanoagents in a combined treatment.