Toxicity of Water-Soluble D-g-PNIPAM Polymers in a Complex with Chemotherapy Drugs and Mechanism of Their Action In Vitro.

The application of a biocompatible polymer nanocarrier can provide target delivery to tumor tissues, improved pharmacokinetics, controlled drug release, etc. Therefore, the proposed strategy was to use the water-soluble star-like copolymers with a Dextran core and Poly(N-isopropylacrylamide) grafts (D-g-PNIPAM) for conjugation with the widely used chemotherapy drugs in oncology-Cisplatin (Cis-Pt) and Doxorubicin (Dox). The molecular characteristics of the copolymer were received using size-exclusion chromatography. The physicochemical characterization of the D-g-PNIPAM-Cis-Pt (or Dox) nanosystem was conducted using dynamic light scattering and FTIR spectroscopy. Using traditional biochemical methods, a comparative analysis of the enhancement of the cytotoxic effect of free Cis-Pt and Dox in combination with D-g-PNIPAM copolymers was performed in cancer cells of the Lewis lung carcinoma line, which are both sensitive and resistant to Dox; in addition, the mechanism of their action in vitro was evaluated.

Comparison of Sonodynamic Treatment Set-Ups for Cancer Cells with Organic Sonosensitizers and Nanosonosensitizers.

Cancer sonodynamic therapy (SDT) is the therapeutic strategy of a high-frequency ultrasound (US) combined with a special sonosensitizer that becomes cytotoxic upon US exposure. The growing number of newly discovered sonosensitizers and custom US in vitro treatment solutions push the SDT field into a need for systemic studies and reproducible in vitro experimental set-ups. In the current research, we aimed to compare two of the most used and suitable SDT in vitro set-ups-"sealed well" and "transducer in well"-in one systematic study. We assessed US pressure, intensity, and temperature distribution in wells under US irradiation. Treatment efficacy was evaluated for both set-ups towards cancer cell lines of different origins, treated with two promising sonosensitizer candidates-carbon nanoparticle C60 fullerene (C60) and herbal alkaloid berberine. C60 was found to exhibit higher sonotoxicity toward cancer cells than berberine. The higher efficacy of sonodynamic treatment with a "transducer in well" set-up than a "sealed well" set-up underlined its promising application for SDT in vitro studies. The "transducer in well" set-up is recommended for in vitro US treatment investigations based on its US-field homogeneity and pronounced cellular effects. Moreover, SDT with C60 and berberine could be exploited as a promising combinative approach for cancer treatment.

The effect of C60 fullerene on the mechanokinetics of muscle gastrocnemius contraction in chronically alcoholized rats.

The C60 fullerene effect (oral administration at a dose of 1 mg kg-1) on the selected biomechanical parameters of muscle gastrocnemius contraction, biochemical indicators of blood and muscle tissue as well as histological changes in rat muscle tissue after chronic alcoholization for 3, 6 and 9 months was studied in detail. Water-soluble C60 fullerenes were shown to reduce the pathological processes development in the muscle apparatus by an average of (35-40)%. In particular, they reduced the time occurrence of fatigue processes in muscle during the long-term development of alcoholic myopathy and inhibited oxidative processes in muscle, thereby preventing its degradation. These findings open up the possibility of using C60 fullerenes as potent antioxidants for the correction of the pathological conditions of the muscle system arising from alcohol intoxication.

Silent Death by Sound: C60 Fullerene Sonodynamic Treatment of Cancer Cells.

The acoustic pressure waves of ultrasound (US) not only penetrate biological tissues deeper than light, but they also generate light emission, termed sonoluminescence. This promoted the idea of its use as an alternative energy source for photosensitizer excitation. Pristine C60 fullerene (C60), an excellent photosensitizer, was explored in the frame of cancer sonodynamic therapy (SDT). For that purpose, we analyzed C60 effects on human cervix carcinoma HeLa cells in combination with a low-intensity US treatment. The time-dependent accumulation of C60 in HeLa cells reached its maximum at 24 h (800 ± 66 ng/106 cells). Half of extranuclear C60 is localized within mitochondria. The efficiency of the C60 nanostructure's sonoexcitation with 1 MHz US was tested with cell-based assays. A significant proapoptotic sonotoxic effect of C60 was found for HeLa cells. C60's ability to induce apoptosis of carcinoma cells after sonoexcitation with US provides a promising novel approach for cancer treatment.

Drug delivery with a pH-sensitive star-like dextran-graft polyacrylamide copolymer.

The development of precision cancer medicine relies on novel formulation strategies for targeted drug delivery to increase the therapeutic outcome. Biocompatible polymer nanoparticles, namely dextran-graft-polyacrylamide (D-g-PAA) copolymers, represent one of the innovative non-invasive approaches for drug delivery applications in cancer therapy. In this study, the star-like D-g-PAA copolymer in anionic form (D-g-PAAan) was developed for pH-triggered targeted drug delivery of the common chemotherapeutic drugs - doxorubicin (Dox) and cisplatin (Cis). The initial D-g-PAA copolymer was synthesized by the radical graft polymerization method, and then alkaline-hydrolyzed to get this polymer in anionic form for further use for drug encapsulation. The acidification of the buffer promoted the release of loaded drugs. D-g-PAAan nanoparticles increased the toxic potential of the drugs against human and mouse lung carcinoma cells (A549 and LLC), but not against normal human lung cells (HEL299). The drug-loaded D-g-PAAan-nanoparticles promoted further oxidative stress and apoptosis induction in LLC cells. D-g-PAAan-nanoparticles improved Dox accumulation and drugs' toxicity in a 3D LLC multi-cellular spheroid model. The data obtained indicate that the strategy of chemotherapeutic drug encapsulation within the branched D-g-PAAan nanoparticle allows not only to realize pH-triggered drug release but also to potentiate its cytotoxic, prooxidant and proapoptotic effects against lung carcinoma cells.

Analysis of Biomechanical and Biochemical Markers of Rat Muscle Soleus Fatigue Processes Development during Long-Term Use of C60 Fullerene and N-Acetylcysteine.

The development of an effective therapy aimed at restoring muscle dysfunctions in clinical and sports medicine, as well as optimizing working activity in general remains an urgent task today. Modern nanobiotechnologies are able to solve many clinical and social health problems, in particular, they offer new therapeutic approaches using biocompatible and bioavailable nanostructures with specific bioactivity. Therefore, the nanosized carbon molecule, C60 fullerene, as a powerful antioxidant, is very attractive. In this study, a comparative analysis of the dynamic of muscle soleus fatigue processes in rats was conducted using 50 Hz stimulation for 5 s with three consistent pools after intraperitoneal administration of the following antioxidants: C60 fullerene (a daily dose of 1 mg/kg one hour prior to the start of the experiment) and N-acetylcysteine (NAC; a daily dose of 150 mg/kg one hour prior to the start of the experiment) during five days. Changes in the integrated power of muscle contraction, levels of the maximum and minimum contraction force generation, time of reduction of the contraction force by 50% of its maximum value, achievement of the maximum force response, and delay of the beginning of a single contraction force response were analyzed as biomechanical markers of fatigue processes. Levels of creatinine, creatine phosphokinase, lactate, and lactate dehydrogenase, as well as pro- and antioxidant balance (thiobarbituric acid reactive substances, hydrogen peroxide, reduced glutathione, and catalase activity) in the blood of rats were analyzed as biochemical markers of fatigue processes. The obtained data indicate that applied therapeutic drugs have the most significant effects on the 2nd and especially the 3rd stimulation pools. Thus, the application of C60 fullerene has a (50-80)% stronger effect on the resumption of muscle biomechanics after the beginning of fatigue than NAC on the first day of the experiment. There is a clear trend toward a positive change in all studied biochemical parameters by about (12-15)% after therapeutic administration of NAC and by (20-25)% after using C60 fullerene throughout the experiment. These findings demonstrate the promise of using C60 fullerenes as potential therapeutic nanoagents that can reduce or adjust the pathological conditions of the muscular system that occur during fatigue processes in skeletal muscles.

Effect of C60 Fullerene on Recovery of Muscle Soleus in Rats after Atrophy Induced by Achillotenotomy.

Biomechanical and biochemical changes in the muscle soleus of rats during imitation of hind limbs unuse were studied in the model of the Achilles tendon rupture (Achillotenotomy). Oral administration of water-soluble C60 fullerene at a dose of 1 mg/kg was used as a therapeutic agent throughout the experiment. Changes in the force of contraction and the integrated power of the muscle, the time to reach the maximum force response, the mechanics of fatigue processes development, in particular, the transition from dentate to smooth tetanus, as well as the levels of pro- and antioxidant balance in the blood of rats on days 15, 30 and 45 after injury were described. The obtained results indicate a promising prospect for C60 fullerene use as a powerful antioxidant for reducing and correcting pathological conditions of the muscular system arising from skeletal muscle atrophy.

C60 fullerene attenuates muscle force reduction in a rat during fatigue development.

C60 fullerene (C60) as a nanocarbon particle, compatible with biological structures, capable of penetrating through cell membranes and effectively scavenging free radicals, is widely used in biomedicine. A protective effect of C60 on the biomechanics of fast (m. gastrocnemius) and slow (m. soleus) muscle contraction in rats and the pro- and antioxidant balance of muscle tissue during the development of muscle fatigue was studied compared to the same effect of the known antioxidant N-acetylcysteine (NAC). C60 and NAC were administered intraperitoneally at doses of 1 and 150 mg kg-1, respectively, daily for 5 days and 1 h before the start of the experiment. The following quantitative markers of muscle fatigue were used: the force of muscle contraction, the level of accumulation of secondary products of lipid peroxidation (TBARS) and the oxygen metabolite H2O2, the activity of first-line antioxidant defense enzymes (superoxide dismutase (SOD) and catalase (CAT)), and the condition of the glutathione system (reduced glutathione (GSH) content and the activity of the glutathione peroxidase (GPx) enzyme). The analysis of the muscle contraction force dynamics in rats against the background of induced muscle fatigue showed, that the effect of C60, 1 h after drug administration, was (15-17)% more effective on fast muscles than on slow muscles. A further slight increase in the effect of C60 was revealed after 2 h of drug injection, (7-9)% in the case of m. gastrocnemius and (5-6)% in the case of m. soleus. An increase in the effect of using C60 occurred within 4 days (the difference between 4 and 5 days did not exceed (3-5)%) and exceeded the effect of NAC by (32-34)%. The analysis of biochemical parameters in rat muscle tissues showed that long-term application of C60 contributed to their decrease by (10-30)% and (5-20)% in fast and slow muscles, respectively, on the 5th day of the experiment. At the same time, the protective effect of C60 was higher compared to NAC by (28-44)%. The obtained results indicate the prospect of using C60 as a potential protective nano agent to improve the efficiency of skeletal muscle function by modifying the reactive oxygen species-dependent mechanisms that play an important role in the processes of muscle fatigue development.

Nanocomplex of Berberine with C60 Fullerene Is a Potent Suppressor of Lewis Lung Carcinoma Cells Invasion In Vitro and Metastatic Activity In Vivo.

Effective targeting of metastasis is considered the main problem in cancer therapy. The development of herbal alkaloid Berberine (Ber)-based anticancer drugs is limited due to Ber' low effective concentration, poor membrane permeability, and short plasma half-life. To overcome these limitations, we used Ber noncovalently bound to C60 fullerene (C60). The complexation between C60 and Ber molecules was evidenced with computer simulation. The aim of the present study was to estimate the effect of the free Ber and C60-Ber nanocomplex in a low Ber equivalent concentration on Lewis lung carcinoma cells (LLC) invasion potential, expression of epithelial-to-mesenchymal transition (EMT) markers in vitro, and the ability of cancer cells to form distant lung metastases in vivo in a mice model of LLC. It was shown that in contrast to free Ber its nanocomplex with C60 demonstrated significantly higher efficiency to suppress invasion potential, to downregulate the level of EMT-inducing transcription factors SNAI1, ZEB1, and TWIST1, to unblock expression of epithelial marker E-cadherin, and to repress cancer stem cells-like markers. More importantly, a relatively low dose of C60-Ber nanocomplex was able to suppress lung metastasis in vivo. These findings indicated that сomplexation of natural alkaloid Ber with C60 can be used as an additional therapeutic strategy against aggressive lung cancer.

C60 fullerene against SARS-CoV-2 coronavirus: an in silico insight.

Based on WHO reports the new SARS-CoV-2 coronavirus is currently widespread all over the world. So far > 162 million cases have been confirmed, including > 3 million deaths. Because of the pandemic still spreading across the globe the accomplishment of computational methods to find new potential mechanisms of virus inhibitions is necessary. According to the fact that C60 fullerene (a sphere-shaped molecule consisting of carbon) has shown inhibitory activity against various protein targets, here the analysis of the potential binding mechanism between SARS-CoV-2 proteins 3CLpro and RdRp with C60 fullerene was done; it has resulted in one and two possible binding mechanisms, respectively. In the case of 3CLpro, C60 fullerene interacts in the catalytic binding pocket. And for RdRp in the first model C60 fullerene blocks RNA synthesis pore and in the second one it prevents binding with Nsp8 co-factor (without this complex formation, RdRp can't perform its initial functions). Then the molecular dynamics simulation confirmed the stability of created complexes. The obtained results might be a basis for other computational studies of 3CLPro and RdRp potential inhibition ways as well as the potential usage of C60 fullerene in the fight against COVID-19 disease.

A New Water-Soluble Thermosensitive Star-Like Copolymer as a Promising Carrier of the Chemotherapeutic Drug Doxorubicin.

A new water-soluble thermosensitive star-like copolymer, dextran-graft-poly-N-iso-propilacrylamide (D-g-PNIPAM), was created and characterized by various techniques (size-exclusion chromatography, differential scanning calorimetry, Fourier-transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS) spectroscopy). The viability of cancer cell lines (human transformed cervix epithelial cells, HeLa) as a model for cancer cells was studied using MTT and Live/Dead assays after incubation with a D-g-PNIPAM copolymer as a carrier for the drug doxorubicin (Dox) as well as a D-g-PNIPAM + Dox mixture as a function of the concentration. FTIR spectroscopy clearly indicated the complex formation of Dox with the D-g-PNIPAM copolymer. The size distribution of particles in Hank's solution was determined by the DLS technique at different temperatures. The in vitro uptake of the studied D-g-PNIPAM + Dox nanoparticles into cancer cells was demonstrated by confocal laser scanning microscopy. It was found that D-g-PNIPAM + Dox nanoparticles in contrast to Dox alone showed higher toxicity toward cancer cells. All of the aforementioned facts indicate a possibility of further preclinical studies of the water-soluble D-g-PNIPAM particles' behavior in animal tumor models in vivo as promising carriers of anticancer agents.

Analysis of Biomechanical Parameters of Muscle Soleus Contraction and Blood Biochemical Parameters in Rat with Chronic Glyphosate Intoxication and Therapeutic Use of C60 Fullerene.

The widespread use of glyphosate as a herbicide in agriculture can lead to the presence of its residues and metabolites in food for human consumption and thus pose a threat to human health. It has been found that glyphosate reduces energy metabolism in the brain, its amount increases in white muscle fibers. At the same time, the effect of chronic use of glyphosate on the dynamic properties of skeletal muscles remains practically unexplored. The selected biomechanical parameters (the integrated power of muscle contraction, the time of reaching the muscle contraction force its maximum value and the reduction of the force response by 50% and 25% of the initial values during stimulation) of muscle soleus contraction in rats, as well as blood biochemical parameters (the levels of creatinine, creatine phosphokinase, lactate, lactate dehydrogenase, thiobarbituric acid reactive substances, hydrogen peroxide, reduced glutathione and catalase) were analyzed after chronic glyphosate intoxication (oral administration at a dose of 10 µg/kg of animal weight) for 30 days. Water-soluble C60 fullerene, as a poweful antioxidant, was used as a therapeutic nanoagent throughout the entire period of intoxication with the above herbicide (oral administration at doses of 0.5 or 1 mg/kg). The data obtained show that the introduction of C60 fullerene at a dose of 0.5 mg/kg reduces the degree of pathological changes by 40-45%. Increasing the dose of C60 fullerene to 1 mg/kg increases the therapeutic effect by 55-65%, normalizing the studied biomechanical and biochemical parameters. Thus, C60 fullerenes can be effective nanotherapeutics in the treatment of glyphosate-based herbicide poisoning.

Anticoronavirus Activity of Water-Soluble Pristine C60 Fullerenes: In Vitro and In Silico Screenings.

INTRODUCTION: The emergence of a new member of the Coronaviridae family, which caused the 2020 pandemic, requires detailed research on the evolution of coronaviruses, their structure and properties, and interaction with cells. Modern nanobiotechnologies can address the many clinical challenges posed by the COVID-19 pandemic. In particular, they offer new therapeutic approaches using biocompatible nanostructures with "specific" antiviral activity. Therefore, the nanosized spherical-like molecule (0.72 nm in diameter) composed of 60 carbon atoms, C60 fullerene, is of interest in terms of fighting coronaviruses due to its high biological activity. In here, we aim to evaluate the effectiveness of anticoronavirus action of water-soluble pristine C60 fullerene in the model and in vitro systems. As a model, apathogenic for human coronavirus, we used transmissible gastroenteritis virus of swine (TGEV), which we adapted to the BHK-21 cell culture (kidney cells of a newborn Syrian hamster). METHODS: The shape and size of the particles present in C60 fullerene aqueous colloidal solution (C60FAS) of given concentration, as well as C60FAS stability (value of zeta potential) were studied using microscopic (STM, scanning tunneling microscopy, and AFM, atomic force microscopy) and spectroscopic (DLS, dynamic light scattering) methods. The cytopathic effect of TGEV was determined with the help of a Leica DM 750 microscope and the degree of monolayer changes in cells was assessed. The microscopy of the viral suspension was performed using a high resolution transmission electron microscope (HRTEM; JEM-1230, Japan). Finally, the search for and design of optimal possible complexes between C60 fullerene and target proteins in the structure of SARS-CoV-2 coronavirus, evaluation of their stability in the simulated cellular environment were performed using molecular dynamics and docking methods. RESULTS: It was found that the maximum allowable cytotoxic concentration of C60 fullerene is 37.5 ± 3.0 µg/ml. The investigated C60FAS reduces the titer of coronavirus infectious activity by the value of 2.00 ± 0.08 TCID50/ml. It was shown that C60 fullerene interacts directly with SARS-CoV-2 proteins, such as RdRp (RNA-dependent RNA polymerase) and 3CLpro (3-chymotrypsin-like protease), which is critical for the life cycle of the coronavirus and, thus, inhibits its functional activity. In both cases, C60 fullerene fills the binding pocket and gets stuck there through stacking and steric interactions. CONCLUSION: Pioneer in vitro study to identify the anticoronavirus activity of water-soluble pristine C60 fullerenes indicates that they are highly promising for further preclinical studies, since a significant inhibition of the infectious activity of swine coronavirus of transmissible gastroenteritis in BHK-21 cell culture was found. According to molecular modeling results, it was shown that C60 fullerene can create the stable complexes with 3CLpro and RdRp proteins of SARS-CoV-2 coronavirus and, thus, suppress its functional activity.

C60 Fullerene Governs Doxorubicin Effect on Metabolic Profile of Rat Microglial Cells In Vitro.

Background: C60 fullerenes and their derivatives are actively investigated for the use in neuroscience. Applications of these nanoscale materials require the examination of their interaction with different neural cells, especially with microglia, because these cells, like other tissue resident phagocytes, are the earliest and most sensitive responders to nanoparticles. The aim of this study was to investigate the effect of C60 fullerene and its nanocomplex with doxorubicin (Dox) on the metabolic profile of brain-resident phagocytes-microglia-in vitro. Methods: Resting microglial cells from adult male Wistar rats were used in experiments. Potential C60 fullerene targets in microglial cells were studied by computer simulation. Microglia oxidative metabolism and phagocytic activity were examined by flow cytometry. Griess reaction and arginase activity colorimetric assay were used to explore arginine metabolism. Results: C60 fullerene when used alone did not influence microglia oxidative metabolism and phagocytic activity but shifted arginine metabolism toward the decrease of NO generation. Complexation of C60 fullerene with Dox (C60-Dox) potentiated the ability of the latter to stimulate NO generation. Conclusion: The capability of C60 fullerenes used alone to cause anti-inflammatory shift of microglia arginine metabolism makes them a promising agent for the correction of neuroinflammatory processes involved in neurodegeneration. The potentiating action of C60 fullerene on the immunomodulatory effect of Dox allows us to consider the C60 molecule as an attractive vehicle for this antitumor agent.

Mode of photoexcited C60 fullerene involvement in potentiating cisplatin toxicity against drug-resistant L1210 cells.

Introduction: C60 fullerene has received great attention as a candidate for biomedical applications. Due to unique structure and properties, C60 fullerene nanoparticles are supposed to be useful in drug delivery, photodynamic therapy (PDT) of cancer, and reversion of tumor cells' multidrug resistance. The aim of this study was to elucidate the possible molecular mechanisms involved in photoexcited C60 fullerene-dependent enhancement of cisplatin toxicity against leukemic cells resistant to cisplatin. Methods: Stable homogeneous pristine C60 fullerene aqueous colloid solution (10-4 М, purity 99.5%) was used in the study. The photoactivation of C60 fullerene accumulated by L1210R cells was done by irradiation in microplates with light-emitting diode lamp (420-700 nm light, 100 mW·cm-2). Cells were further incubated with the addition of Cis-Pt to a final concentration of 1 µg/mL. Activation of p38 MAPK was visualized by Western blot analysis. Flow cytometry was used for the estimation of cells distribution on cell cycle. Mitochondrial membrane potential (Δψm) was estimated with the use of fluorescent potential-sensitive probe TMRE (Tetramethylrhodamine Ethyl Ester). Results: Cis-Pt applied alone at 1 µg/mL concentration failed to affect mitochondrial membrane potential in L1210R cells or cell cycle distribution as compared with untreated cells. Activation of ROS-sensitive proapoptotic p38 kinase and enhanced content of cells in subG1 phase were detected after irradiation of L1210R cells treated with 10-5M C60 fullerene. Combined treatment with photoexcited C60 fullerene and Cis-Pt was followed by the dissipation of Δψm at early-term period, blockage of cell transition into S phase, and considerable accumulation of cells in proapoptotic subG1 phase at prolonged incubation. Conclusion: The effect of the synergic cytotoxic activity of both agents allowed to suppose that photoexcited C60 fullerene promoted Cis-Pt accumulation in leukemic cells resistant to Cis-Pt. The data obtained could be useful for the development of new approaches to overcome drug-resistance of leukemic cells.

Synergy of Chemo- and Photodynamic Therapies with C60 Fullerene-Doxorubicin Nanocomplex.

A nanosized drug complex was explored to improve the efficiency of cancer chemotherapy, complementing it with nanodelivery and photodynamic therapy. For this, nanomolar amounts of a non-covalent nanocomplex of Doxorubicin (Dox) with carbon nanoparticle C60 fullerene (C60) were applied in 1:1 and 2:1 molar ratio, exploiting C60 both as a drug-carrier and as a photosensitizer. The fluorescence microscopy analysis of human leukemic CCRF-CEM cells, in vitro cancer model, treated with nanocomplexes showed Dox's nuclear and C60's extranuclear localization. It gave an opportunity to realize a double hit strategy against cancer cells based on Dox's antiproliferative activity and C60's photoinduced pro-oxidant activity. When cells were treated with 2:1 C60-Dox and irradiated at 405 nm the high cytotoxicity of photo-irradiated C60-Dox enabled a nanomolar concentration of Dox and C60 to efficiently kill cancer cells in vitro. The high pro-oxidant and pro-apoptotic efficiency decreased IC50 16, 9 and 7 × 103-fold, if compared with the action of Dox, non-irradiated nanocomplex, and C60's photodynamic effect, correspondingly. Hereafter, a strong synergy of therapy arising from the combination of C60-mediated Dox delivery and C60 photoexcitation was revealed. Our data indicate that a combination of chemo- and photodynamic therapies with C60-Dox nanoformulation provides a promising synergetic approach for cancer treatment.

C60 Fullerene as an Effective Nanoplatform of Alkaloid Berberine Delivery into Leukemic Cells.

A herbal alkaloid Berberine (Ber), used for centuries in Ayurvedic, Chinese, Middle-Eastern, and native American folk medicines, is nowadays proved to function as a safe anticancer agent. Yet, its poor water solubility, stability, and bioavailability hinder clinical application. In this study, we have explored a nanosized carbon nanoparticle-C60 fullerene (C60)-for optimized Ber delivery into leukemic cells. Water dispersions of noncovalent C60-Ber nanocomplexes in the 1:2, 1:1, and 2:1 molar ratios were prepared. UV-Vis spectroscopy, dynamic light scattering (DLS), and atomic force microscopy (AFM) evidenced a complexation of the Ber cation with the negatively charged C60 molecule. The computer simulation showed that π-stacking dominates in Ber and C60 binding in an aqueous solution. Complexation with C60 was found to promote Ber intracellular uptake. By increasing C60 concentration, the C60-Ber nanocomplexes exhibited higher antiproliferative potential towards CCRF-CEM cells, in accordance with the following order: free Ber < 1:2 < 1:1 < 2:1 (the most toxic). The activation of caspase 3/7 and accumulation in the sub-G1 phase of CCRF-CEM cells treated with C60-Ber nanocomplexes evidenced apoptosis induction. Thus, this study indicates that the fast and easy noncovalent complexation of alkaloid Ber with C60 improved its in vitro efficiency against cancer cells.

Toxicity of C60 fullerene-cisplatin nanocomplex against Lewis lung carcinoma cells.

Cisplatin (Cis-Pt) is the cytotoxic agent widely used against tumors of various origin, but its therapeutic efficiency is substantially limited by a non-selective effect and high toxicity. Conjugation of Cis-Pt with nanocarriers is thought to be one option to enable drug targeting. The aim of this study was to estimate toxic effects of the nanocomplex formed by noncovalent interaction of C60 fullerene with Cis-Pt against Lewis lung carcinoma (LLC) cells in comparison with free drug. Scanning tunneling microscopy showed that the minimum size of C60-Cis-Pt nanoparticles in aqueous colloid solution was 1.1 nm whereas that of C60 fullerene was 0.72 nm, thus confirming formation of the nanocomplex. The cytotoxic effect of C60-Cis-Pt nanocomplex against LLC cells was shown to be higher with IC50 values 3.3 and 4.5 times lower at 48 h and 72 h, respectively, as compared to the free drug. 12.5 µM Cis-Pt had no effect on LLC cell viability and morphology while C60-Cis-Pt nanocomplex in Cis-Pt-equivalent concentration substantially decreased the cell viability, impaired their shape and adhesion, inhibited migration and induced accumulation in proapoptotic subG1 phase. Apoptosis induced by the C60-Cis-Pt nanocomplex was confirmed by caspase 3/7 activation and externalization of phosphatidylserine on the outer surface of LLC cells with the double Annexin V-FITC/PI staining. We assume that C60 fullerene as a component of the C60-Cis-Pt nanocomplex promoted Cis-Pt entry and intracellular accumulation thus contributing to intensification of the drug's toxic effect against lung cancer cells.

Correction to: Complexation with C60 Fullerene Increases Doxorubicin Efficiency against Leukemic Cells In Vitro.

Following publication of the original article [1], the authors flagged that there was unfortunately an error with Fig. 3 of the article.

Complexation with C60 Fullerene Increases Doxorubicin Efficiency against Leukemic Cells In Vitro.

Conventional anticancer chemotherapy is limited because of severe side effects as well as a quickly evolving multidrug resistance of the tumor cells. To address this problem, we have explored a C60 fullerene-based nanosized system as a carrier for anticancer drugs for an optimized drug delivery to leukemic cells.Here, we studied the physicochemical properties and anticancer activity of C60 fullerene noncovalent complexes with the commonly used anticancer drug doxorubicin. C60-Doxorubicin complexes in a ratio 1:1 and 2:1 were characterized with UV/Vis spectrometry, dynamic light scattering, and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The obtained analytical data indicated that the 140-nm complexes were stable and could be used for biological applications. In leukemic cell lines (CCRF-CEM, Jurkat, THP1 and Molt-16), the nanocomplexes revealed ≤ 3.5 higher cytotoxic potential in comparison with the free drug in a range of nanomolar concentrations. Also, the intracellular drug's level evidenced C60 fullerene considerable nanocarrier function.The results of this study indicated that C60 fullerene-based delivery nanocomplexes had a potential value for optimization of doxorubicin efficiency against leukemic cells.