Interactions between modified fullerenes and proteins in cancer nanotechnology.

Fullerenes have numerous properties that fill the gap between small molecules and nanomaterials. Several types of chemical reaction allow their surface to be ornamented with functional groups designed to change them into 'ideal' nanodelivery systems. Improved stability, and bioavailability are important, but chemical modifications can render them practically soluble in water. 'Buckyball' fullerene scaffolds can interact with many biological targets and inhibit several proteins essential for tumorigeneses. Herein, we focus on the inhibitory properties of fullerene nanomaterials against essential proteins in cancer nanotechnology, as well as the use of dedicated proteins to improve the bioavailability of these promising nanomaterials.

Identification and Biological Evaluation of a Water-Soluble Fullerene Nanomaterial as BTK Kinase Inhibitor.

Introduction: Thanks to recent advances in synthetic methodology, water-soluble fullerene nanomaterials that interfere with biomolecules, especially DNA/RNA and selected proteins, have been found with tremendous potential for applications in nanomedicine. Herein, we describe the synthesis and evaluation of a water-soluble glycine-derived [60]fullerene hexakisadduct (HDGF) with T h symmetry, which is a first-in-class BTK protein inhibitor. Methods: We synthesized and characterized glycine derived [60]fullerene using NMR, ESI-MS, and ATR-FT-IR. DLS and zeta potential were measured and high-resolution transmission electron microscopy (HRTEM) observations were performed. The chemical composition of the water-soluble fullerene nanomaterial was examined by X-ray photoelectron spectrometry. To observe aggregate formation, the cryo-TEM analysis was carried out. The docking studies and molecular dynamic simulations were performed to determine interactions between HDGF and BTK. The in vitro cytotoxicity was evaluated on RAJI and K562 blood cancer cell lines. Subsequently, we examined the induction of cell death by autophagy and apoptosis by determining the expression levels of crucial genes and caspases. We investigated the direct association of HDGF on inhibition of the BTK signalling pathway by examining changes in the calcium levels in RAJI cells after treatment. The inhibitory potential of HDGF against non-receptor tyrosine kinases was evaluated. Finally, we assessed the effects of HDGF and ibrutinib on the expression of the BTK protein and downstream signal transduction in RAJI cells following anti-IgM stimulation. Results: Computational studies revealed that the inhibitory activity of the obtained [60]fullerene derivative is multifaceted: it hampers the BTK active site, interacting directly with the catalytic residues, rendering it inaccessible to phosphorylation, and binds to residues that form the ATP binding pocket. The anticancer activity of produced carbon nanomaterial revealed that it inhibited the BTK protein and its downstream pathways, including PLC and Akt proteins, at the cellular level. The mechanistic studies suggested the formation of autophagosomes (increased gene expression of LC3 and p62) and two caspases (caspase-3 and -9) were responsible for the activation and progression of apoptosis. Conclusion: These data illustrate the potential of fullerene-based BTK protein inhibitors as nanotherapeutics for blood cancer and provide helpful information to support the future development of fullerene nanomaterials as a novel class of enzyme inhibitors.

Uncovering nanotoxicity of a water-soluble and red-fluorescent [70]fullerene nanomaterial.

Engineered fullerene materials have attracted the attention of researchers in the biomedical sciences, especially when their synthetic methodology is developed to endow them with significant levels of water-solubility and bioavailability. In this study, we synthesized and characterized a water-soluble and red-fluorescent [70]fullerene nanomaterial, which fluoresced at 693 nm with a quantum yield of 0.065 and a large Stokes shift (around 300 nm). The fullerene nanomaterial generated mainly singlet oxygen after illumination with blue LED light, while superoxide anion radical production was minimal. The transmission electron microscopy as well as fluorescent studies of Drosophila melanogaster revealed that prepared [70]fullerene nanoparticles had better bioavailability than pristine [70]fullerene nanoparticles. The designed nanomaterials were observed in the apical, perinuclear, and basal regions of digestive cells, as well as the basal lamina of the digestive system's epithelium, with no damage to cell organelles and no activation of degenerative processes and cell death. Our findings provide a new perspective for understanding the in vivo behavior of fullerene nanomaterials and their future application in bioimaging and light-activated nanotherapeutics.

Recent Advancements on Self-Immolative System Based on Dynamic Covalent Bonds for Delivering Heterogeneous Payloads.

The precisely spatial-temporal delivery of heterogeneous payloads from a single system with the same pulse is in great demand in realizing versatile and synergistic functions. Very few molecular architectures can satisfy the strict requirements of dual-release translated from single triggers, while the self-immolative systems based on dynamic covalent bonds represent the "state-of-art" of ultimate solution strategy. Embedding heterogeneous payloads symmetrically onto the self-immolative backbone with dynamic covalent bonds as the trigger, can respond to the quasi-bio-orthogonal hallmarks which are higher at the disease's microenvironment to simultaneously yield the heterogeneous payloads (drug A/drug B or drug/reporter). In this review, the modular design principles are concentrated to illustrate the rules in tailoring useful structures, then the rational applications are enumerated on the aspects of drug codelivery and visualized drug-delivery. This review, hopefully, can give the general readers a comprehensive understanding of the self-immolative systems based on dynamic covalent bonds for delivering heterogeneous payloads.

Compound Nanoemulsion Combined with Differentiation/Cytotoxicity Drugs for Modulating Breast Cancer Stemness.

Breast cancer stem cells (BCSCs) are the culprit of triple-negative breast cancer invasiveness and are heterogeneous. It is recognized that the combination of chemotherapy and differentiation therapy for killing BCSCs and non-BCSCs simultaneously is a reliable strategy. In this study, an oil-in-water nanoemulsion was prepared by high-pressure homogenization with coencapsulation of all-trans retinoic acid (ATRA) and doxorubicin (DOX). The preparation process was simple, and the production was easy to scale up. The particle size of the nanoemulsion was 127.2 ± 2.0 nm. Cellular toxicity assay showed that the composite index of the ATRA and DOX was less than 1 and exhibited a fine combined effect. In vivo antitumor efficacy showed that the compound nanoemulsion could reduce the proportion of BCSCs to 1.18% by inhibiting the expression of Pin1. In addition, the combination of ATRA and DOX could reduce the cardiotoxicity of DOX and had higher safety. Hopefully, this work can provide a new insight into developing pharmaceutically acceptable technology for treating BCSCs.

In Situ Cellular Localization of Nonfluorescent [60]Fullerene Nanomaterial in MCF-7 Breast Cancer Cells.

Cellular localization of carbon nanomaterials in cancer cells is essential information for better understanding their interaction with biological targets and a crucial factor for further evaluating their biological properties as nanovehicles or nanotherapeutics. Recently, increasing efforts to develop promising fullerene nanotherapeutics for cancer nanotechnology have been made. However, the main challenge regarding studying their cellular effects is the lack of effective methods for their visualization and determining their cellular fate due to the limited fluorescence of buckyball scaffolds. Herein, we developed a method for cellular localization of nonfluorescent and water-soluble fullerene nanomaterials using the in vitro click chemistry approach. First, we synthesized a triple-bonded fullerene probe (TBC60ser), which was further used as a starting material for 1,3-dipolar cycloaddition using 3-azido-7-hydroxycoumarin and sulfo-cyanine5 azide fluorophores to create fluorescent fullerene triazoles. In this work, we characterized the structurally triple-bonded [60]fullerene derivative and confirmed its high symmetry (Th) and the successful formation of fullerene triazoles by spectroscopic techniques (i.e., ultraviolet-visible, fluorescence, and Fourier transform infrared spectroscopies) and mass spectrometry. The created fluorescent fullerene triazoles were successfully localized in the MCF-7 breast cancer cell line using fluorescent microscopy. Overall, our findings demonstrate that TBC60ser localizes in the lysosomes of MCF-7 cells, with only a small affinity to mitochondria.

Ultrasensitive and selective determination of mercury in water, beverages and food samples by EDXRF and TXRF using graphene oxide modified with thiosemicarbazide.

The paper presents novel analytical methods for sensitive mercury determination in various samples, i.e., waters, beverages, seafood, plants, and biological samples. The procedure is based on selective preconcentration/separation of Hg(II) ions using graphene oxide/thiosemicarbazide in dispersive micro-solid phase extraction (DMSPE) and detection by energy-dispersive (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The DMSPE/EDXRF and DMSPE/TXRF procedures are characterized by very high enrichment factors and low detection limits (LODs). DMSPE/TXRF allows obtaining LODs of 2.1 pg mL-1 for liquids and 1.8 ng g-1 for solid samples. In the case of DMSPE/EDXRF, the LODs are higher, 60 pg mL-1 for liquid and 73 ng g-1 for solid samples, due to the worse sensitivity of EDXRF measurement. The method was validated using spiked samples (water, apple juice, beer, wine) and certified reference materials (seawater, groundwater, wastewater, herring, cormorant and cod tissues, pig kidney, lobster, tobacco, scallion, celery, and spinach).

Synthesis and applications of [60]fullerene nanoconjugate with 5-aminolevulinic acid and its glycoconjugate as drug delivery vehicles.

The 5-aminolevulinic acid (5-ALA) prodrug is widely used in clinical applications, primarily for skin cancer treatments and to visualize brain tumors in neurosurgery. Unfortunately, its applications are limited by unfavorable pharmacological properties, especially low lipophilicity; therefore, efficient nanovehicles are needed. For this purpose, we synthesized and characterized two novel water-soluble fullerene nanomaterials containing 5-ALA and d-glucuronic acid components. Their physicochemical properties were investigated using NMR, XPS, ESI mass spectrometry, as well as TEM and SEM techniques. In addition, HPLC and fluorescence measurements were performed to evaluate the biological activity of the fullerene nanomaterials in 5-ALA delivery and photodynamic therapy (PDT); additional detection of selected mRNA targets was carried out using the qRT-PCR methodology. The cellular response to the [60]fullerene conjugates resulted in increased levels of ABCG2 and PEPT-1 genes, as determined by qRT-PCR analysis. Therefore, we designed a combination PDT approach based on two fullerene materials, C60-ALA and C60-ALA-GA, along with the ABCG2 inhibitor Ko143.

Towards water-soluble [60]fullerenes for the delivery of siRNA in a prostate cancer model.

This paper presents two water-soluble fullerene nanomaterials (HexakisaminoC60 and monoglucosamineC60, which is called here JK39) that were developed and synthesized as non-viral siRNA transfection nanosystems. The developed two-step Bingel-Hirsch reaction enables the chemical modification of the fullerene scaffold with the desired bioactive fragments such as D-glucosamine while keeping the crucial positive charged ethylenediamine based malonate. The ESI-MS and 13C-NMR analyses of JK39 confirmed its high Th symmetry, while X-ray photoelectron spectroscopy revealed the presence of nitrogen and oxygen-containing C-O or C-N bonds. The efficiency of both fullerenes as siRNA vehicles was tested in vitro using the prostate cancer cell line DU145 expressing the GFP protein. The HexakisaminoC60 fullerene was an efficient siRNA transfection agent, and decreased the GFP fluorescence signal significantly in the DU145 cells. Surprisingly, the glycofullerene JK39 was inactive in the transfection experiments, probably due to its high zeta potential and the formation of an extremely stable complex with siRNA.

Interactions of a Water-Soluble Glycofullerene with Glucose Transporter 1. Analysis of the Cellular Effects on a Pancreatic Tumor Model.

In recent years, carbon nanomaterials have been intensively investigated for their possible applications in biomedical studies, especially as drug delivery vehicles. Several surface modifications can modulate the unique molecular structure of [60]fullerene derivatives, as well as their physicochemical properties. For this reason, covalent modifications that would enable a greater water solubilization of the fullerene buckyball have been rapidly investigated. The most exciting applications of fullerene nanomaterials are as drug delivery vectors, photosensitizers in photodynamic therapy (PDT), astransfection or MRI contrast agents, antimicrobials and antioxidants. From these perspectives, the glucose derivatives of [60]fullerene seem to be an interesting carbon nanomaterial for biological studies. It is well-known that cancer cells are characterized by an increased glucose uptake and it has also been previously reported that the glucose transporters (GLUTs) are overexpressed in several types of cancers, which make them attractive molecular targets for many drugs. This study explored the use of a highly water-soluble glycofullerene (called Sweet-C60) in pancreatic cancer studies. Here, we describe the PANC-1 cell proliferation, migration, metabolic activity and glycolysis rate after incubations with different concentrations of Sweet-C60. The final results did not show any influence of the Sweet-C60 on various cancer cellular events and glycolysis, suggesting that synthesized glycofullerene is a promising drug delivery vehicle for treating pancreatic cancer.

Developing [60]Fullerene Nanomaterials for Better Photodynamic Treatment of Non-Melanoma Skin Cancers.

Skin cancer is the most common cancer in the U.S.A. and Europe. Its subtype, squamous skin carcinoma (SCC), if allowed to grow, has the potential to metastasize and can become deadly. Currently, carbon nanomaterials are being developed to treat cancer due to their attractive physicochemical and biological properties such as an enhanced permeability effect and their ability to produce reactive oxygen species. Here, we describe the synthesis of two water-soluble aminofullerenes (MonoaminoC60 and HexakisaminoC60), which were evaluated as novel [60]fullerene based photosentizers exhibiting anticancer properties. Moreover, the previously described neutral glycofullerene GF1 and its peracetylated lipophilic precursor MMS48 were compared with the aminofullerenes for their ability to generate reactive oxygen species and oxidize lipids. Remarkably, the generation of singlet oxygen and a superoxide radical by HexakisaminoC60 was found to be markedly elevated in the presence of bovine serum albumin and NADH, respectively. Mechanistic studies of lipid peroxidation using cholesterol as a unique reporter molecule revealed that although all four fullerene nanomaterials primarily generated singlet oxygen, superoxide anion was also formed, which suggest a mixed mechanism of action (in which Type I and Type II photochemistry is involved). The [60]fullerene derivative HexakisaminoC60 was also studied for its phototoxicity in squamous skin cancer cell line (A431) using the MTT test and propidium iodide staining.

Glycofullerenes as non-receptor tyrosine kinase inhibitors- towards better nanotherapeutics for pancreatic cancer treatment.

The water-soluble glycofullerenes GF1 and GF2 were synthesized using two-step modified Bingel-Hirsch methodology. Interestingly, we identified buckyballs as a novel class of non-receptor Src kinases inhibitors. The evaluated compounds were found to inhibit Fyn A and BTK proteins with IC50 values in the low micromolar range, with the most active compound at 39 µM. Moreover, we have demonstrated that formation of protein corona on the surface of [60]fullerene derivatives is changing the landscape of their activity, tuning the selectivity of obtained carbon nanomaterials towards Fyn A and BTK kinases. The performed molecular biology studies revealed no cytotoxicity and no influence of engineered carbon nanomaterials on the cell cycle of PANC-1 and AsPC-1 cancer cell lines. Incubation with the tested compounds resulted in the cellular redox imbalance triggering the repair systems and influenced the changing of protein levels.

A water-soluble [60]fullerene-derivative stimulates chlorophyll accumulation and has no toxic effect on Chlamydomonas reinhardtii.

Chlamydomonas reinhardtii (WT 2137) P. A. Dang. (Volvocales, Chlorophyceae) is a green microalgae serving as a suitable model in scientific research and a promising industrial biotechnology platform for production of biofuel, hydrogen and recombinant proteins. Fullerenes (C60) are allotropic carbon nanoparticles discovered in 1985 and used in biomedical studies since the early 1990s, when water solubilization methodologies were developed. Recently, surface-modified hydroxylated derivatives of fullerenes were proven to enhance algal growth and drought tolerance in plants. Here, a novel type of water-soluble [60]fullerene derivative with 12 glycine residues (GF) has been synthesized and tested for acute toxicity (up to 50 µg/ml) and as a potential biostimulant of algal growth. The effects of GF on pigment composition and growth rate of Chlamydomonas reinhardtii were systematically investigated. Our results suggest that GF was not toxic, and no negative change in the pigment content and no stress symptoms were observed. No changes in the photosynthetic parameters based on the fluorescence of chlorophyll a in Photosystem II (NPQ, Fv/Fm, Fv/F0, PI and RC/ABS) were observed. The GF had no effect on cell size and growth rate. At a concentration of 20 µg/ml, GF stimulated chlorophyll accumulation in 3-day-old cultures.

Development of photoactive Sweet-C60 for pancreatic cancer stellate cell therapy.

AIM: Glycoconjugated C60 derivatives are of particular interest as potential cancer targeting agents due to an upregulated metabolic glucose demand, especially in the case of pancreatic adenocarcinoma and its dense stroma, which is known to be driven by a subset of pancreatic stellate cells. MATERIALS & METHODS: Herein, we describe the synthesis and biological characterization of a hexakis-glucosamine C60 derivative (termed 'Sweet-C60'). RESULTS: Synthesized fullerene derivative predominantly accumulates in the nucleus of pancreatic stellate cells; is inherently nontoxic up to concentrations of 1 mg/ml; and is photoactive when illuminated with blue and green light, allowing its use as a photodynamic therapy agent. CONCLUSION: Obtained glycoconjugated nanoplatform is a promising nanotherapeutic for pancreatic cancer.

The role of oxidative stress in activity of anticancer thiosemicarbazones.

Thiosemicarbazones are chelators of transition metals such as iron or copper whose anticancer potency is intensively investigated. Although two compounds from this class have entered clinical trials, their precise mechanism of action is still unknown. Recent studies have suggested the mobilization of the iron ions from a cell, as well as the inhibition of ribonucleotide reductase, and the formation of reactive oxygen species. The complexity and vague nature of this mechanism not only impedes a more rational design of novel compounds, but also the further development of those that are highly active that are already in the preclinical phase. In the current work, a series of highly active thiosemicarbazones was studied for their antiproliferative activity in vitro. Our experiments indicate that these complexes have ionophoric properties and redox activity. They appeared to be very effective generating reactive oxygen species and deregulating the antioxidative potential of a cell. Moreover, the genes that are responsible for antioxidant capacity were considerably deregulated, which led to the induction of apoptosis and cell cycle arrest. On the other hand, good intercalating properties of the studied compounds may explain their ability to cleave DNA strands and to also poison related enzymes through the formation of reactive oxygen species. These findings may help to explain the particularly high selectivity that they have over normal cells, which generally have a stronger redox equilibrium.

Iron Chelators and Exogenic Photosensitizers. Synergy through Oxidative Stress Gene Expression.

In non-invasive anticancer photodynamic therapy (PDT), a nontoxic photosensitizer (PS), which is activated by visible light, is used as a magic bullet that selectively destroys cancer cells. Recently, we described the combined therapy of 5-aminolevulinic acid (ALA-PDT) with thiosemicarbazone (TSC), i.e. an iron-chelating agent. This resulted in a strong synergistic effect. Herein, we investigated a novel strategy using a combination of PDT consist of the xenobiotic-porphyrin type PS with TSC. We observed a synergistic effect for all of the pairs of TSC-PS. This approach can be rationalized by the fact that both chlorin and TSC can affect the generation of reactive oxygen species (ROS). In order to elucidate the plausible mechanism of action, we also combined the investigated PSs with DFO, which forms complexes that are redox inactive. We detected a slight antagonism or additivity for this combination. This may suggest that the ability of an iron chelator (IC) to participate in the production of ROS and the generation of oxidative stress is important.

The effects of non-invasive radiofrequency electric field hyperthermia on biotransport and biodistribution of fluorescent [60]fullerene derivative in a murine orthotopic model of breast adenocarcinoma.

The aim of this study is to understand the combined and differential biokinetic effects of radiofrequency (RF) electric-field hyperthermia as an adjunctive therapy to [60]fullerene nanoparticle-based drug delivery systems in targeting the micro-vasculature and micro-environments of breast cancer tumors. Intravital microscopy (IVM) is an ideal tool to provide the spatial and temporal resolution needed for quantification in this investigation. The water-soluble and fluorescent [60]fullerene derivative (C60-serPF) was designed to be an amphiphilic nanostructure, which is able to cross several biological membranes and accumulate in tumor tissues by passing through abnormally leaky tumor blood vessels. To elucidate the coupled effects of the highly permeable, but heterogeneous tumor vasculature, with the permeabilizing effects of mild (40-42°C) hyperthermia produced by a local RF field, we controlled variables across tumor and non-tumor mammary gland microvasculature with and without application of RF hyperthermia in each condition. We notice that tumor tissue is characterized by more intense drug extravasation than in contralateral mammary fat pad tissue, which is consistent with enhanced permeability and retention (EPR) effects. The analysis of a permeability parameter (Papp), C60-serPF velocity, and the time of compound influx into the intra- and extra-vascular space suggest that mild RF hyperthermia can improve nanoparticle delivery into tumor tissue.

Optimizing non-invasive radiofrequency hyperthermia treatment for improving drug delivery in 4T1 mouse breast cancer model.

Interactions of high-frequency radio waves (RF) with biological tissues are currently being investigated as a therapeutic platform for non-invasive cancer hyperthermia therapy. RF delivers thermal energy into tissues, which increases intra-tumoral drug perfusion and blood-flow. Herein, we describe an optical-based method to optimize the short-term treatment schedules of drug and hyperthermia administration in a 4T1 breast cancer model via RF, with the aim of maximizing drug localization and homogenous distribution within the tumor microenvironment. This method, based on the analysis of fluorescent dyes localized into the tumor, is more time, cost and resource efficient, when compared to current analytical methods for tumor-targeting drug analysis such as HPLC and LC-MS. Alexa-Albumin 647 nm fluorphore was chosen as a surrogate for nab-paclitaxel based on its similar molecular weight and albumin driven pharmacokinetics. We found that RF hyperthermia induced a 30-40% increase in Alexa-Albumin into the tumor micro-environment 24 h after treatment when compared to non-heat treated mice. Additionally, we showed that the RF method of delivering hyperthermia to tumors was more localized and uniform across the tumor mass when compared to other methods of heating. Lastly, we provided insight into some of the factors that influence the delivery of RF hyperthermia to tumors.

EPR Imaging Spin Probe Trityl Radical OX063: A Method for Its Isolation from Animal Effluent, Redox Chemistry of Its Quinone Methide Oxidation Product, and in Vivo Application in a Mouse.

We report herein a method for the recovery, purification, and application of OX063, a costly, commercially available nontoxic spin probe widely used for electron paramagnetic resonance (EPR) imaging, as well as its corresponding quinone methide (QM) form. This precious probe can be successfully recovered after use in animal model experiments (25-47% recovery from crude lyophilizate with 98.5% purity), even from samples that are >2 years old. Significantly, the recovered trityl can be reused in further animal model EPR imaging experiments. The work also describes support for the observed formation of an air-sensitive radical derived from the QM under reducing conditions.