Application of fullerenes in nanomedicine: an update

C60 Fullerenes Diminish Muscle Fatigue in Rats Comparable to N-acetylcysteine or β-Alanine

The aim of this study is to detect the effects of C60 fullerenes, which possess pronounced antioxidant properties, in comparison with the actions of the known exogenous antioxidants N-acetylcysteine (NAC) and β-Alanine in terms of exercise tolerance and contractile property changes of the m. triceps surae (TS) during development of the muscle fatigue in rats. The electrical stimulation of the TS muscle during four 30 min series in control rats led to total reduction of the muscle contraction force. Furthermore, the effects of prior intraperitoneal (i.p.) or oral C60FAS application and preliminary i.p. injection of NAC or β-Alanine on muscle contraction force under fatigue development conditions is studied. In contrast to control rats, animals with C60FAS, NAC, or β-Alanine administration could maintain a constant level of muscle effort over five stimulation series. The accumulation of secondary products and changes in antioxidant levels in the muscle tissues were also determined after the fatigue tests. The increased levels of lactic acid, thiobarbituric acid reactive substances and H2O2 after stimulation were statistically significant with respect to intact muscles. In the working muscle, there was a significant (p < 0.05) increase in the activity of endogenous antioxidants: reduced glutathione, catalase, glutathione peroxidase, and superoxide dismutase. Treated animal groups showed a decrease in endogenous antioxidant activity relative to the fatigue-induced animals (P < 0.05). Oral C60FAS administration clearly demonstrated an action on skeletal muscle fatigue development similar to the effects of i.p. injections of the exogenous antioxidants NAC or β-Alanine. This creates opportunities to oral use of C60FAS as a potential therapeutic agent. Due to the membranotropic activity of C60 fullerenes, non-toxic C60FAS has a more pronounced effect on the prooxidant-antioxidant homeostasis of muscle tissues in rats.

C60 Bioconjugation with Proteins: Towards a Palette of Carriers for All pH Ranges

The high hydrophobicity of fullerenes and the resulting formation of aggregates in aqueous solutions hamper the possibility of their exploitation in many technological applications. Noncovalent bioconjugation of fullerenes with proteins is an emerging approach for their dispersion in aqueous media. Contrary to covalent functionalization, bioconjugation preserves the physicochemical properties of the carbon nanostructure. The unique photophysical and photochemical properties of fullerenes are then fully accessible for applications in nanomedicine, sensoristic, biocatalysis and materials science fields. However, proteins are not universal carriers. Their stability depends on the biological conditions for which they have evolved. Here we present two model systems based on pepsin and trypsin. These proteins have opposite net charge at physiological pH. They recognize and disperse C60 in water. UV-Vis spectroscopy, zeta-potential and atomic force microscopy analysis demonstrates that the hybrids are well dispersed and stable in a wide range of pH’s and ionic strengths. A previously validated modelling approach identifies the protein-binding pocket involved in the interaction with C60. Computational predictions, combined with experimental investigations, provide powerful tools to design tailor-made C60@proteins bioconjugates for specific applications.

Metabolic Responses of Mytilus galloprovincialis to Fullerenes in Mesocosm Exposure Experiments

In this study, Mediterranean mussels (Mytilus galloprovincialis) were exposed through the diet to fullerene soot at three concentrations in parallel to a control group. Their metabolomics response was assessed by high-performance liquid chromatography coupled to high-resolution mass spectrometry (HPLC-HRMS). The experiments were conducted in marine mesocosms, during 35 days (7 days of acclimatization, 21 days of exposure, and 7 days of depuration). Real conditions were emulated in terms of physicochemical conditions of the habitat. Results confirmed the bioaccumulation of fullerenes, and the metabolome of the exposed organisms revealed significant differences in the concentrations of seven free amino acids in comparison to the control group. An increase in small nonpolar amino acids (e.g., alanine) and branched chain amino acids (leucine and isoleucine) were observed. Also, glutamine concentrations decreased significantly, suggesting the activation of facultative anaerobic energy metabolism. Branched chain amino acids, such as leucine and isoleucine, followed the opposite trend after the highest level of exposure, which can imply hormesis effects. Other significant differences were observed on lipids content, such as the general increase of free fatty acids, i.e., long-chain fatty acids (lauric, myristic, and palmitic acids) when the concentration of exposure was increased. These results were consistent with hypoxia and oxidative stress.

C60 fullerenes disrupt cellular signalling leading to TRPC4 and TRPC6 channels opening by the activation of muscarinic receptors and G-proteins in small intestinal smooth muscles

The effect of water-soluble pristine C₆₀ fullerene nanoparticles (C₆₀NPs) on receptor-operated cation channels formed by TRPC4/C6 proteins in ileal smooth muscle cells was investigated for the first time. Activation of these channels subsequent to acetylcholine binding to the expressed in these cells M₂ and M₃ muscarinic receptors represents the key event in the parasympathetic control of gastrointestinal smooth muscle motility and cholinergic excitation-contraction coupling. Experiments were performed on single collagenase-dispersed mouse ileal myocytes using patch-clamp techniques with symmetrical 125mM Cs⁺ solutions and [Ca²⁺]_i 'clamped' at 100nM in order to isolate the muscarinic cation current (mI_CAT). The current was induced by intracellular infusion of 200μM GTPγS, which activates G-proteins directly, i.e. bypassing the muscarinic receptors. C₆₀NPs applied at 10^-6M at peak response to activation of G-proteins caused mI_CAT inhibition by 47.0±3.5% (n=9). The inhibition developed rather slowly, with the time constant of 119±16s, was voltage-independent and irreversible. Thus, C₆₀NPs are unlikely to cause any direct block of TRPC4/C6 channels; rather, they may accumulate in the membrane and disrupt G-protein signalling leading to mI_CAT generation. C₆₀NPs may represent a novel class of biocompatible molecules for the treatment of disorders associated with enhanced gastrointestinal motility.

Fullerene (C60) particle size implications in neurotoxicity following infusion into the hippocampi of Wistar rats

The buckminsterfullerene (C60) is considered as a relevant candidate for drug and gene delivery to the brain, once it has the ability to cross the blood-brain barrier. However, the biological implications of this nanomaterial are not fully understood, and its safety for intracerebral delivery is still debatable. In this study, we investigated if C60 particle size could alter its biological effects. For this, two aqueous C60 suspensions were used with maximum particle size up to 200nm and 450nm. The suspensions were injected in the hippocampus, the main brain structure involved in memory processing and spatial localization. In order to assess spatial learning, male Wistar rats were tested in Morris water maze, and the hippocampal BDNF protein levels and gene expression were analyzed. Animals treated with C60 up to 450nm demonstrated impaired spatial memory with a significant decrease in BDNF protein levels and gene expression. However, an enhanced antioxidant capacity was observed in both C60 treatments. A decrease in reactive oxygen species levels was observed in the treatments with suspensions containing particles measuring with up to 450nm. Thiobarbituric acid reactive substances, glutamate cysteine ligase, and glutathione levels showed no alterations among the different treatments. In conclusion, different particle sizes of the same nanomaterial can lead to different behavioral outcomes and biochemical parameters in brain tissue.

Antioxidant nanomaterials in advanced diagnoses and treatments of ischemia reperfusion injuries

Organ ischemia with inadequate oxygen supply followed by reperfusion (which initiates a complex of inflammatory responses and oxidative stress) occurs in different clinical conditions and surgical procedures including stroke, myocardial infarction, limb ischemia, renal failure, organ transplantation, free-tissue-transfer, cardiopulmonary bypass, and vascular surgery. Even though pharmacological treatments protect against experimental ischemia reperfusion (I/R) injury, there has not been enough success in their application for patient benefits. The main hurdles in the treatment of I/R injury are the lack of diagnosis tools for understanding the complicated chains of I/R-induced signaling events, especially in the acute phase after ischemia, determining the affected regions of the tissue over time, and then, targeting and safe delivery of antioxidants, drugs, peptides, genes and cells to the areas requiring treatment. Besides the innate antioxidant and free radical scavenging properties, some nanoparticles also show higher flexibility in drug delivery and imaging. This review highlights three main approaches in nanoparticle-mediated targeting of I/R injury: nanoparticles (1) as antioxidants for reducing tissue oxidative stress, (2) for targeted delivery of therapeutic agents to the ischemic regions or cells, and (3) for imaging I/R injury at the molecular, cellular or tissue level and monitoring its evolution using contrasts induced by nanoparticles. These approaches can also be combined to realize so called theranostics for providing simultaneous diagnosis of ischemic regions and treatments by targeted delivery.

Characterizing the Nano-Bio Interface Using Microscopic Techniques: Imaging the Cell System is Just as Important as Imaging the Nanoparticle System

The rapid growth of nanotechnology and its industries has elevated the need to understand the risks associated with handling, using, and disposing of nanomaterials. These risks can be assessed through exposure measurement and hazard identification. One of the common challenges associated with quantifying nanomaterials in products, waste, humans, or the environment is the lack of tools available to measure concentration. The ability of refined tools and techniques to qualitatively detect nanoparticles in complex matrices has been demonstrated. For biological and ecological tests systems, dose can be represented as initial concentration in the applied matrix, concentration administered during the route of exposure, concentration at the target organ, and intake concentration at the cellular level. Each of these concentration measurements requires different sets of tools to perform accurate analyses. Advances in microscopy techniques provide new opportunities for reporting observations occurring at the interaction of a nanoparticle with a biomolecular entity of similar size within a biological test(s) system. This protocol outlines the steps to image nanomaterials within cell-based systems. © 2017 by John Wiley & Sons, Inc.

Advances in biotechnological synthetic applications of carbon nanostructured systems

In the last few years carbon nanostructures have been applied for the immobilization of enzymes and biomimetic organo-metallic species useful for biotechnological applications. The nature of the support and the method of immobilization are responsible for the stability, reactivity and selectivity of the system. In this review, we focus on the recent advances in the use of carbon nanostructures, carbon nanotubes, carbon nanorods, fullerene and graphene for the preparation of biocatalytic and biomimetic systems and for their application in the development of green chemical processes.

NF-κB inhibitors that prevent foam cell formation and atherosclerotic plaque accumulation

The transformation of monocyte-derived macrophages into lipid-laden foam cells is one inflammatory process underlying atherosclerotic disease. Previous studies have demonstrated that fullerene derivatives (FDs) have inflammation-blunting properties. Thus, it was hypothesized that FD could inhibit the transformation process underlying foam cell formation. Fullerene derivatives inhibited the phorbol myristic acid/oxidized low-density lipoprotein-induced differentiation of macrophages into foam cells as determined by lipid staining and morphology.Lipoprotein-induced generation of TNF-α, C5a-induced MC activation, ICAM-1 driven adhesion, and CD36 expression were significantly inhibited in FD treated cells compared to non-treated cells. Inhibition appeared to be mediated through the NF-κB pathway as FD reduced expression of NF-κB and atherosclerosis-associated genes. Compared to controls, FD dramatically inhibited plaque formation in arteries of apolipoprotein E null mice. Thus, FD may be an unrecognized therapy to prevent atherosclerotic lesions via inhibition of foam cell formation and MC stabilization.

Permeation of skin with (C60) fullerene dispersions

Dispersions in transcutol/isopropyl myristate make C₆₀ fullerene molecules suitable for transdermal delivery. We found that C₆₀ can successfully permeate the skin using pig skin in Franz diffusion cells. Molecular dynamics simulations and transmission electron microscopy confirmed these observations. Basic cosmetic formulations with transcutol/isopropyl myristate without harsh organic solvents show a high potential for delivery of C₆₀ for biopharmaceutical and cosmetics applications.

Theoretical identification of seven C80 fullerene isomers by XPS and NEXAFS spectroscopy

The molecular geometries and C1s NEXAFS spectra of seven IPR-satisfying isomers of fullerene C₈₀.

When a nanoparticle meets a superhalogen: a case study with C60 fullerene

The ability of a selected nanoparticle to form stable systems with superhalogens (i.e. AlF4, AlCl4, MgF3, MgCl3, LiF2, LiCl2, and LiI2) is examined on the basis of theoretical considerations supported by ab initio calculations. It is demonstrated that the C60 fullerene molecule should form stable and strongly bound (C60)˙(+)(superhalogen)(-) radical cation salts when combined with an appropriately chosen superhalogen radical (acting as an oxidizing agent). The conclusion is supported by providing: (i) the structural deformation of superhalogens and C60 nanoparticles upon ionization, (ii) predicted charge flow between the fullerene and each superhalogen (which allows estimating the amount of electron density withdrawn from the C60 molecule during the ionization process), (iii) the localization of the spin density distribution, and (iv) the interaction energies for the compounds obtained both at the B3LYP/6-31+G(d) level and at the B3LYP-D3/6-31+G(d) level. Solvent effects have been considered in the present study by means of the polarizable continuum model. It is found that the stability of C60/superhalogen species can be improved in solvents. We believe that the results provided in this contribution may likely be of prospective relevance in the future studies on the issue of binding and removal of this potentially risky nanoparticle.

A comparison of immunotoxic effects of nanomedicinal products with regulatory immunotoxicity testing requirements

Nanomaterials (NMs) are attractive for biomedical and pharmaceutical applications because of their unique physicochemical and biological properties. A major application area of NMs is drug delivery. Many nanomedicinal products (NMPs) currently on the market or in clinical trials are most often based on liposomal products or polymer conjugates. NMPs can be designed to target specific tissues, eg, tumors. In virtually all cases, NMPs will eventually reach the immune system. It has been shown that most NMs end up in organs of the mononuclear phagocytic system, notably liver and spleen. Adverse immune effects, including allergy, hypersensitivity, and immunosuppression, have been reported after NMP administration. Interactions of NMPs with the immune system may therefore constitute important side effects. Currently, no regulatory documents are specifically dedicated to evaluate the immunotoxicity of NMs or NMPs. Their immunotoxicity assessment is performed based on existing guidelines for conventional substances or medicinal products. Due to the unique properties of NMPs when compared with conventional medicinal products, it is uncertain whether the currently prescribed set of tests provides sufficient information for an adequate evaluation of potential immunotoxicity of NMPs. The aim of this study was therefore, to compare the current regulatory immunotoxicity testing requirements with the accumulating knowledge on immunotoxic effects of NMPs in order to identify potential gaps in the safety assessment. This comparison showed that immunotoxic effects, such as complement activation-related pseudoallergy, myelosuppression, inflammasome activation, and hypersensitivity, are not readily detected by using current testing guidelines. Immunotoxicity of NMPs would be more accurately evaluated by an expanded testing strategy that is equipped to stratify applicable testing for the various types of NMPs.

Synthesis and characterization of multifunctional superparamagnetic iron oxide nanoparticles (SPION)/C60 nanocomposites assembled by fullerene–amine click chemistry

We used fullerene–amine click chemistry for the fabrication of SPION/C₆₀ nanocomposites that bring together the superparamagnetic character conferred by the SPION-core and the photochemical and antioxidant activities provided by the C₆₀.

Biological potential of nanomaterials strongly depends on the suspension media: experimental data on the effects of fullerene C₆₀ on membranes

Fullerenes (C60) are some of the most promising carbon nanomaterials to be used for medical applications as drug delivery agents. Computational and experimental studies have proposed their ability to enter cells by penetrating lipid bilayers. The aim of our study was to provide experimental evidence on whether pristine C60 in physiological media could penetrate cell membranes. The effect was tested on phospholipid vesicles (liposomes) composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, and validated on isolated human red blood cells (RBCs). We incubated the liposomes in an aqueous suspension of C60 and dissolved the lipids and C60 together in chloroform and subsequently formatted the liposomes. By differential scanning calorimetry measurements, we assessed the effect of C60 on the phospholipid thermal profile. The latter was not affected after the incubation of liposomes in the C60 suspension; also, a shape transformation of RBCs did not occur. Differently, by dispersing both C60 and the phospholipids in chloroform, we confirmed the possible interaction of C60 with the bilayer. We provide experimental data suggesting that the suspension medium is an important factor in determining the C60-membrane interaction, which is not always included in computational studies. Since the primary particle size is not the only crucial parameter in C60-membrane interactions, it is important to determine the most relevant characteristics of their effects on membranes.

Biological interactions of carbon-based nanomaterials: From coronation to degradation

Carbon-based nanomaterials including carbon nanotubes, graphene oxide, fullerenes and nanodiamonds are potential candidates for various applications in medicine such as drug delivery and imaging. However, the successful translation of nanomaterials for biomedical applications is predicated on a detailed understanding of the biological interactions of these materials. Indeed, the potential impact of the so-called bio-corona of proteins, lipids, and other biomolecules on the fate of nanomaterials in the body should not be ignored. Enzymatic degradation of carbon-based nanomaterials by immune-competent cells serves as a special case of bio-corona interactions with important implications for the medical use of such nanomaterials. In the present review, we highlight emerging biomedical applications of carbon-based nanomaterials. We also discuss recent studies on nanomaterial 'coronation' and how this impacts on biodistribution and targeting along with studies on the enzymatic degradation of carbon-based nanomaterials, and the role of surface modification of nanomaterials for these biological interactions.

FROM THE CLINICAL EDITOR

Advances in technology have produced many carbon-based nanomaterials. These are increasingly being investigated for the use in diagnostics and therapeutics. Nonetheless, there remains a knowledge gap in terms of the understanding of the biological interactions of these materials. In this paper, the authors provided a comprehensive review on the recent biomedical applications and the interactions of various carbon-based nanomaterials.

Characterization of C60 fullerene complexation with antibiotic doxorubicin

The aim of this paper was to provide the physico-chemical characterization of a key process leading to amplification of the antitumor effect of antibiotic Doxorubicin (Dox) in vivo and in vitro and occurring at the molecular level through complexation with C60 fullerene. A wide range of physico-chemical tools was used such as UV/Vis and NMR spectroscopies, atomic force microscopy, isothermal titration calorimetry and zeta-potential methods. The unusual thermodynamic behavior of the complexation process was reported, featuring unexpected and, to a certain extent, contradictory experimental observations. The explanation of the obtained results was proposed resulting in creation of a general view on aromatic drug binding with C60 fullerene. Based on these results some important practical outcomes for anticancer therapy were formulated.

Emerging therapeutic delivery capabilities and challenges utilizing enzyme/protein packaged bacterial vesicles

Nanoparticle-based therapeutics are poised to play a critical role in treating disease. These complex multifunctional drug delivery vehicles provide for the passive and active targeted delivery of numerous small molecule, peptide and protein-derived pharmaceuticals. This article will first discuss some of the current state of the art nanoparticle classes (dendrimers, lipid-based, polymeric and inorganic), highlighting benefits/drawbacks associated with their implementation. We will then discuss an emerging class of nanoparticle therapeutics, bacterial outer membrane vesicles, that can provide many of the nanoparticle benefits while simplifying assembly. Through molecular biology techniques; outer membrane vesicle hijacking potentially allows for stringent control over nanoparticle production allowing for targeted protein packaged nanoparticles to be fully synthesized by bacteria.

A zeta potential value determines the aggregate's size of penta-substituted [60]fullerene derivatives in aqueous suspension whereas positive charge is required for toxicity against bacterial cells

Background

The cause–effect relationships between physicochemical properties of amphiphilic [60]fullerene derivatives and their toxicity against bacterial cells have not yet been clarified. In this study, we report how the differences in the chemical structure of organic addends in 10 originally synthesized penta-substituted [60]fullerene derivatives modulate their zeta potential and aggregate’s size in salt-free and salt-added aqueous suspensions as well as how these physicochemical characteristics affect the bioenergetics of freshwater Escherichia coli and marine Photobacterium phosphoreum bacteria. Dynamic light scattering, laser Doppler micro-electrophoresis, agarose gel electrophoresis, atomic force microscopy, and bioluminescence inhibition assay were used to characterize the fullerene aggregation behavior in aqueous solution and their interaction with the bacterial cell surface, following zeta potential changes and toxic effects.

Results

Dynamic light scattering results indicated the formation of self-assembled [60]fullerene aggregates in aqueous suspensions. The measurement of the zeta potential of the particles revealed that they have different surface charges. The relationship between these physicochemical characteristics was presented as an exponential regression that correctly described the dependence of the aggregate’s size of penta-substituted [60]fullerene derivatives in salt-free aqueous suspension from zeta potential value. The prevalence of DLVO-related effects was shown in salt-added aqueous suspension that decreased zeta potential values and affected the aggregation of [60]fullerene derivatives expressed differently for individual compounds. A bioluminescence inhibition assay demonstrated that the toxic effect of [60]fullerene derivatives against E. coli cells was strictly determined by their positive zeta potential charge value being weakened against P. phosphoreum cells in an aquatic system of high salinity. Atomic force microscopy data suggested that the activity of positively charged [60]fullerene derivatives against bacterial cells required their direct interaction. The following zeta potential inversion on the bacterial cells surface was observed as an early stage of toxicity mechanism that violates the membrane-associated energetic functions.

Conclusions

The novel data about interrelations between physicochemical parameters and toxic properties of amphiphilic [60]fullerene derivatives make possible predicting their behavior in aquatic environment and their activity against bacterial cells.

Supramolecular nanoscale assemblies for cancer diagnosis and therapy

Nanocarriers based on polymers, metals and lipids have been extensively developed for cancer therapy and diagnosis due to their ability to enhance drug accumulation in cancer cells and decrease undesired drug toxicity in healthy tissues. Overcoming multidrug resistance by designing proper drug nanocarriers will improve outcome of existing oncologic treatments such as chemotherapy and radiotherapy. In this article the relation between physicochemical properties and capacity of a nanosystem to deliver therapeutic agents into pathological sites is discussed. Most promising examples of drug delivery systems are reviewed, and, in particular, the design of a carbohydrate based matrix with entrapped gold nanoparticles is highlighted.

Theranostic applications of carbon nanomaterials in cancer: Focus on imaging and cargo delivery

Carbon based nanomaterials have attracted significant attention over the past decades due to their unique physical properties, versatile functionalization chemistry, and biological compatibility. In this review, we will summarize the current state-of-the-art applications of carbon nanomaterials in cancer imaging and drug delivery/therapy. The carbon nanomaterials will be categorized into fullerenes, nanotubes, nanohorns, nanodiamonds, nanodots and graphene derivatives based on their morphologies. The chemical conjugation/functionalization strategies of each category will be introduced before focusing on their applications in cancer imaging (fluorescence/bioluminescence, magnetic resonance (MR), positron emission tomography (PET), single-photon emission computed tomography (SPECT), photoacoustic, Raman imaging, etc.) and cargo (chemo/gene/therapy) delivery. The advantages and limitations of each category and the potential clinical utilization of these carbon nanomaterials will be discussed. Multifunctional carbon nanoplatforms have the potential to serve as optimal candidates for image-guided delivery vectors for cancer.

C70-carboxyfullerenes as efficient antioxidants to protect cells against oxidative-induced stress

Oxidative stress induced by excessive production of reactive oxygen species (ROS) has been implicated in the etiology of many human diseases. Acquiring a highly efficient antioxidant with good biocompatibility is of significance in eliminating the deleterious effect induced by the oxidative stress. Herein, we address our efforts on investigating the cytoprotective effect of carboxyfullerenes on H2O2-injured cells. Meanwhile, the uptake and intracellular location of carboxyfullerenes were studied. The results show that C70-carboxyfullerenes (dimalonic acid C70 fullerene (DF70) and trimalonic acid C70 fullerene (TF70)) exhibit an obviously protective effect against oxidative stress on C2C12 cells at concentrations as low as 2.5 μmol L(-1), whereas C60-carboxyfullerenes (dimalonic acid C60 fullerene (DF60) and quadri-malonic acid C60 fullerene (QF60)) show a protective effect at relatively higher concentration (40 μmol L(-1)). The molecular structure of carboxyfullerenes and the physiological state of cells play an important role in the different cytoprotective capability. Further study reveals that DF70 and TF70 could enter into cells and mainly localize into the lysosome, which possibly involves the protective mechanism by stabilizing lysosome. The use of a significantly low concentration of C70-carboxyfullerene as the antioxidative agent will benefit the therapeutic approaches aiming at alleviating ROS-induced injuries such as muscle disorder and arthritis.

Liposome formulation of fullerene-based molecular diagnostic and therapeutic agents

Fullerene medicine is a new but rapidly growing research subject. Fullerene has a number of desired structural, physical and chemical properties to be adapted for biological use including antioxidants, anti-aging, anti-inflammation, photodynamic therapy, drug delivery, and magnetic resonance imaging contrast agents. Chemical functionalization of fullerenes has led to several interesting compounds with very promising preclinical efficacy, pharmacokinetic and safety data. However, there is no clinical evaluation or human use except in fullerene-based cosmetic products for human skincare. This article summarizes recent advances in liposome formulation of fullerenes for the use in therapeutics and molecular imaging.