Graphene Oxide Loaded with Protocatechuic Acid and Chlorogenic Acid Dual Drug Nanodelivery System for Human Hepatocellular Carcinoma Therapeutic Application.

Hepatocellular carcinoma or hepatoma is a primary malignant neoplasm that responsible for 75-90% of all liver cancer in humans. Nanotechnology introduced the dual drug nanodelivery method as one of the initiatives in nanomedicine for cancer therapy. Graphene oxide (GO) loaded with protocatechuic acid (PCA) and chlorogenic acid (CA) have shown some anticancer activities in both passive and active targeting. The physicochemical characterizations for nanocomposites were conducted. Cell cytotoxicity assay and lactate dehydrogenase were conducted to estimate cell cytotoxicity and the severity of cell damage. Next, nanocomposite intracellular drug uptake was analyzed using a transmission electron microscope. The accumulation and localization of fluorescent-labelled nanocomposite in the human hepatocellular carcinoma (HepG2) cells were analyzed using a fluorescent microscope. Subsequently, Annexin V- fluorescein isothiocyanate (FITC)/propidium iodide analysis showed that nanocomposites induced late apoptosis in HepG2 cells. Cell cycle arrest was ascertained at the G2/M phase. There was the depolarization of mitochondrial membrane potential and an upregulation of reactive oxygen species when HepG2 cells were induced by nanocomposites. In conclusion, HepG2 cells treated with a graphene oxide-polyethylene glycol (GOP)-PCA/CA-FA dual drug nanocomposite exhibited significant anticancer activities with less toxicity compared to pristine protocatechuic acid, chlorogenic acid and GOP-PCA/CA nanocomposite, may be due to the utilization of a folic acid-targeting nanodrug delivery system.

Biodistribution of Graphene Oxide Determined through Postadministration Labeling with DNA-Conjugated Gold Nanoparticles and ICPMS.

Recent research has revealed the use of graphene oxide (GO) and its derivatives as a potential biomaterial because of their attractive physicochemical characteristics and functional properties. However, if GO and related derivatives are to become useful materials for biomedical applications, it will be necessary to evaluate their biodistribution for health and safety considerations. To obtain a more accurate biodistribution for GO, we (i) developed a postadministration labeling strategy employing DNA-conjugated gold nanoparticles (DNA-AuNPs) to selectively label administered GO in Solvable-treated tissue samples and (ii) constructed an automatic sample pretreatment scheme (using a C18-packed minicolumn) to effectively separate the DNA-AuNP-labeled GO from the unbound DNA-AuNPs and the dissolved tissue matrices, thereby enabling ultrasensitive, interference-free quantification of GO through measurement (inductively coupled plasma mass spectrometry) of the Au signal intensities. The DNA-AuNPs can bind to GO in a concentration- and time-dependent manner. After optimizing the labeling conditions (DNA length, incubation pH, DNA-AuNP concentration, and incubation time) and the separation scheme (sample loading flow rate, rinsing volume, and eluent composition), we found that A20R20-AuNPs (R20: random DNA sequence including A, T, C, and G) had the strongest binding affinity for labeling of the administered GO (dissociation constant: 36.0 fM) and that the method's detection limit reached 9.3 ag L-1 with a calibration curve having a working range from 10-1 to 1010 fg L-1. Moreover, this approach revealed that the intravenously administered GO accumulated predominantly in the liver and spleen at 1 and 12 h post administration, with apparent discrepancies in the concentrations measured using pre- and postadministration labeling strategies.

Toxic effects of different-sized graphene oxide particles on zebrafish embryonic development.

Graphene oxide (GO) has broad application potential in many fields, such as biomedicine and energy. Due to the wide-ranging GO applications, its entry into the environment is inevitable along with the potential for ecological and environmental risks. In the present study, we systematically investigated the dose-dependent effects of three different-sized GO particles (50-200 nm, <500 nm, and >500 nm) on zebrafish during the very early developmental stages (4-124 h post-fertilization). The results showed that GOs could accumulate in the eyes, heart, yolk sac, and blood vessels of fish larvae. Consequently, their effects on multiple toxic endpoints were observed, including delayed hatching times, shortened body lengths, alterations in heart rate and blood flow, changes in swimming activity and responses to photoperiod stimulation, and the enhanced activity of total superoxide dismutase, inducible nitric oxide synthase, acetylcholinesterase, caspase-3, and induction of apoptosis-related gene expression. As a result, the occurrence of oxidative stress and the induction of apoptosis are suggested in fish larvae exposed to all three different-sized GO particles. In addition, our results highlight the impacts of waterborne-GO exposure on zebrafish during early development, which were not merely dependent on GO concentration but also on the associated GO sizes. This study hereby provides a basis for the potential ecological and health risks of GO exposure.

Dual-Sensitive Graphene Oxide Loaded with Proapoptotic Peptides and Anticancer Drugs for Cancer Synergetic Therapy.

A dual-sensitive drug delivery system (DDS) based on graphene oxide (GO) which is simultaneously loaded with proapoptotic peptides and anticancer drugs was rationally designed and fabricated for cancer synergetic therapy. Specifically, a kind of cell apoptosis peptide (KLAKLAK)2 (KLA) was anchored on the surface of GO via a disulfide bond to obtain GO-SS-KLA. Then, the aromatic anticancer drug doxorubicin (DOX) was loaded on GO through π-π conjugation and hydrogen bonding interactions. Finally, bovine serum albumin (BSA) was used to coat the GO carrier to obtain a biological medium-stable GO-based DDS, DOX@GO-SS-KLA/BSA. The results show that KLA and DOX can be released responding to the reductive and pH stimulus inside the cells, respectively, and achieve a synergetic therapy for cancer. Moreover, the results of stability studies show that DOX@GO-SS-KLA/BSA could be stably dispersed in water for more than 8 days and in 10% fetal bovine serum for at least 6 days. The constructed DOX@GO-SS-KLA/BSA exhibits great potential as a drug carrier for co-delivery of various therapeutic agents.

Cytotoxicity profile of pristine graphene on brain microvascular endothelial cells.

Graphene-based nanomaterials hold the potential to be used in a wide variety of applications, including biomedical devices. Pristine graphene (PG) is an un-functionalized, defect-free type of graphene that could be used as a material for neural interfacing. However, the neurotoxic effects of PG, particularly to the blood-brain barrier (BBB), have not been fully studied. The BBB separates the brain tissue from the circulating substances in the blood and is essential to maintain the brain homeostasis. The principal components of the BBB are brain microvascular endothelial cells (BMVECs), which maintain a protectively low permeability due to the expression of tight junction proteins. Here we analyzed the effects of PG on BMVECs in an in vitro model of the BBB. BMVECs were treated with PG at 0, 10, 50 and 100 µg/mL for 24 hours and viability and functional analyses of BBB integrity were performed. PG increased lactate dehydrogenase release at 50 and 100 µg/mL, suggesting the induction of necrosis. Surprisingly, 2,3,-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)-carbonyl]-2H-tetrazolium (XTT) conversion was increased at 10 and 50 µg/mL. In contrast, XTT conversion was decreased at 100 µg/mL, suggesting the induction of cell death. In addition, 100 µg/mL PG increased DNA fragmentation, suggesting induction of apoptosis. At the same time, 50 and 100 µg/mL of PG increased the endothelial permeability, which corresponded with a decrease in the expression of the tight junction protein occludin at 100 µg/mL. In conclusion, these results suggest that PG negatively affects the viability and function of the BBB endothelial cells in vitro.

Graphene-based materials: The missing piece in nanomedicine?

Nanomedicine utilizes biocompatible nanomaterials for therapeutic as well as imaging purposes for the treatment of various diseases including cancer, neurological disorders and wound infections. Graphene and its modified nanostructures have attracted much attention in recent years in nanomedicine owing to their scalable and cost effective preparation and physiochemical features (high specific surface area, ease in conjugation to peptides/antibodies/proteins and biocompatibility). However, the limited fabrication, functionalization, and in vivo functionalities available in literature indicate inconsistencies regarding the factors affecting in vivo metabolisms, biodistribution as well as toxicity patterns of graphene. It appears that redox signaling pathways, and their proper use to target specific diseases and to improve biocompatibility and interplay between size and optical properties are key determinants to investigate the metabolic fate of such materials. This featured letter provides key insights into the significance and multifunctional roles of redox regulated species in graphene-based materials which can be used to closely mimic therapeutic functions, navigating new paths to nanomedicine and synthetic biology. Furthermore, this letter focuses on the missing functionalities and challenges in using graphene-based materials as both nano-carriers and nano-drugs in various biomedical sectors which might be favorable for multiple payloads and drug targeting in upcoming years.

Evaluating the evidence on genotoxicity and reproductive toxicity of carbon black: a critical review.

Carbon black is produced industrially by the partial combustion or thermal decomposition of gaseous or liquid hydrocarbons under controlled conditions. It is considered a poorly soluble, low toxicity (PSLT) particle. Recently, results from a number of published studies have suggested that carbon black may be directly genotoxic, and that it may also cause reproductive toxicity. Here, we review the evidence from these studies to determine whether carbon black is likely to act as a primary genotoxicant or reproductive toxicant in humans. For the genotoxicity endpoint, the available evidence clearly shows that carbon black does not directly interact with DNA. However, the study results are consistent with the mechanism that, at high enough concentrations, carbon black causes inflammation and oxidative stress in the lung leading to mutations, which is a secondary genotoxic mechanism. For the reproductive toxicity endpoint for carbon black, to date, there are various lung instillation studies and one short-term inhalation study that evaluated a selected number of reproduction endpoints (e.g. gestational and litter parameters) as well as other general endpoints (e.g. gene expression, neurofunction, DNA damage); usually at one time point or using a single dose. It is possible that some of the adverse effects observed in these studies may be the result of non-specific inflammatory effects caused by high exposure doses. An oral gavage study reported no adverse reproductive or developmental effects at the highest dose tested. The overall weight of evidence indicates that carbon black should not be considered a direct genotoxicant or reproductive toxicant.

Graphene quantum dots in alveolar macrophage: uptake-exocytosis, accumulation in nuclei, nuclear responses and DNA cleavage.

BACKGROUND: Given the tremendous potential for graphene quantum dots (QDs) in biomedical applications, a thorough understanding of the interaction of these materials with macrophages is essential because macrophages are one of the most important barriers against exogenous particles. Although the cytotoxicity and cellular uptake of graphene QDs were reported in previous studies, the interaction between nuclei and the internalized graphene QDs is not well understood. We thus systematically studied the nuclear uptake and related nuclear response associated with aminated graphene QDs (AG-QDs) exposure. RESULTS: AG-QDs showed modest 24-h inhibition to rat alveolar macrophages (NR8383), with a minimum inhibitory concentration (MIC) of 200 µg/mL. Early apoptosis was significantly increased by AG-QDs (100 and 200 µg/mL) exposure and played a major role in cell death. The internalization of AG-QDs was mainly via energy-dependent endocytosis, phagocytosis and caveolae-mediated endocytosis. After a 48-h clearance period, more than half of the internalized AG-QDs remained in the cellular cytoplasm and nucleus. Moreover, AG-QDs were effectively accumulated in nucleus and were likely regulated by two nuclear pore complexes genes (Kapß2 and Nup98). AG-QDs were shown to alter the morphology, area, viability and nuclear components of exposed cells. Significant cleavage and cross-linking of DNA chains after AG-QDs exposure were confirmed by atomic force microscopy investigation. Molecular docking simulations showed that H-bonding and π-π stacking were the dominant forces mediating the interactions between AG-QDs and DNA, and were the important mechanisms resulting in DNA chain cleavage. In addition, the generation of reactive oxygen species (ROS) (e.g., •OH), and the up-regulation of caspase genes also contributed to DNA cleavage. CONCLUSIONS: AG-QDs were internalized by macrophages and accumulated in nuclei, which further resulted in nuclear damage and DNA cleavage. It is demonstrated that oxidative damage, direct contact via H-bonding and π-π stacking, and the up-regulation of caspase genes are the primary mechanisms for the observed DNA cleavage by AG-QDs.

Developmental basis for intestinal barrier against the toxicity of graphene oxide.

BACKGROUND: Intestinal barrier is crucial for animals against translocation of engineered nanomaterials (ENMs) into secondary targeted organs. However, the molecular mechanisms for the role of intestinal barrier against ENMs toxicity are still largely unclear. The intestine of Caenorhabditis elegans is a powerful in vivo experimental system for the study on intestinal function. In this study, we investigated the molecular basis for intestinal barrier against toxicity and translocation of graphene oxide (GO) using C. elegans as a model animal. RESULTS: Based on the genetic screen of genes required for the control of intestinal development at different aspects using intestine-specific RNA interference (RNAi) technique, we identified four genes (erm-1, pkc-3, hmp-2 and act-5) required for the function of intestinal barrier against GO toxicity. Under normal conditions, mutation of any of these genes altered the intestinal permeability. With the focus on PKC-3, an atypical protein kinase C, we identified an intestinal signaling cascade of PKC-3-SEC-8-WTS-1, which implies that PKC-3 might regulate intestinal permeability and GO toxicity by affecting the function of SEC-8-mediated exocyst complex and the role of WTS-1 in maintaining integrity of apical intestinal membrane. ISP-1 and SOD-3, two proteins required for the control of oxidative stress, were also identified as downstream targets for PKC-3, and functioned in parallel with WTS-1 in the regulation of GO toxicity. CONCLUSIONS: Using C. elegans as an in vivo assay system, we found that several developmental genes required for the control of intestinal development regulated both the intestinal permeability and the GO toxicity. With the focus on PKC-3, we raised two intestinal signaling cascades, PKC-3-SEC-8-WTS-1 and PKC-3-ISP-1/SOD-3. Our results will strengthen our understanding the molecular basis for developmental machinery of intestinal barrier against GO toxicity and translocation in animals.

Functional disruption in epidermal barrier enhances toxicity and accumulation of graphene oxide.

In Caenorhabditis elegans, mutation of mlt-7 causes the deficits in epidermal barrier. Using the nematodes with epidermal-specific RNA interference (RNAi) knockdown of mlt-7 as a genetic tool, we found that epidermal-specific RNAi knockdown of mlt-7 resulted in a susceptibility to graphene oxide (GO) toxicity, and enhanced GO accumulation in the body. Epidermal-development related proteins of BLI-1 and IFB-1 acted as downstream targets of MLT-7, and mediated the function of MLT-7 in maintaining the epidermal barrier. Antimicrobial proteins of NLP-30 and CNC-2 also acted as downstream targets of MLT-7 in the regulation of GO toxicity. Epidermal-specific RNAi knockdown of nlp-30 or cnc-2 enhanced GO toxicity and accumulation in bli-1(RNAi) or ifb-1(RNAi) nematodes. Our data highlights the importance of maintaining normal epidermal barrier for nematodes against the GO toxicity.

Tumor Cell-Specific Nuclear Targeting of Functionalized Graphene Quantum Dots In Vivo.

Specific targeting of tumor tissues is essential for tumor imaging and therapeutics but remains challenging. Here, we report an unprecedented method using synthetic sulfonic-graphene quantum dots (sulfonic-GQDs) to exactly target the cancer cell nuclei in vivo without any bio- ligand modification, with no intervention in cells of normal tissues. The key factor for such selectivity is the high interstitial fluid pressure (IFP) in tumor tissues, which allows the penetration of sulfonic-GQDs into the plasma membrane of tumor cells. In vitro, the sulfonic-GQDs are repelled out of the cell membrane because of the repulsive force between negatively charged sulfonic-GQDs and the cell membranes which contributes to the low distribution in normal tissues in vivo. However, the plasma membrane-crossing process can be activated by incubating cells in ultrathin film culture medium because of the attachment of sulfonic-GQDs on cell memebranes. Molecular dynamics simulations demonstrated that, once transported across the plasma membrane, the negatively charged functional groups of these GQDs will leave the membrane with a self-cleaning function retaining a small enough size to achieve penetration through the nuclear membrane into the nucleus. Our study showed that IFP is a previously unrecognized mechanism for specific targeting of tumor cell nuclei and suggested that sulfonic-GQDs may be developed into novel tools for tumor-specific imaging and therapeutics.

Bioaccumulation and Toxicity of 13C-Skeleton Labeled Graphene Oxide in Wheat.

Graphene nanomaterials have many diverse applications, but are considered to be emerging environmental pollutants. Thus, their potential environmental risks and biosafety are receiving increased attention. Bioaccumulation and toxicity evaluations in plants are essential for biosafety assessment. In this study, 13C-stable isotope labeling of the carbon skeleton of graphene oxide (GO) was applied to investigate the bioaccumulation and toxicity of GO in wheat. Bioaccumulation of GO was accurately quantified according to the 13C/12C ratio. Wheat seedlings were exposed to 13C-labeled GO at 1.0 mg/mL in nutrient solution for 15 d. 13C-GO accumulated predominantly in the root with a content of 112 µg/g at day 15, hindered the development and growth of wheat plants, disrupted root structure and cellular ultrastructure, and promoted oxidative stress. The GO that accumulated in the root showed extremely limited translocation to the stem and leaves. During the experimental period, GO was excreted slowly from the root. GO inhibited the germination of wheat seeds at high concentrations (≥0.4 mg/mL). The mechanism of GO toxicity to wheat may be associated with oxidative stress induced by GO bioaccumulation, reflected by the changes of malondialdehyde concentration, catalase activity, and peroxidase activity. The results demonstrate that 13C labeling is a promising method to investigate environmental impacts and fates of carbon nanomaterials in biological systems.

Normalization of doxorubicin release from graphene oxide: New approach for optimization of effective parameters on drug loading.

Graphene oxide (GO) has been recently introduced as a suitable anticancer drug carrier, which could be loaded with doxorubicin (DOX) as a general chemotherapy agent. Herein, the attempts were made to optimize the effective parameters on both loading and release of DOX on GO. GO and GO-DOX were characterized using transition electron microscopy , zeta potential, Raman spectroscopy, UV-visible spectroscopy, and Fourier transform infrared spectroscopy. In addition, loading and releasing behaviors of DOX on GO were studied in terms of different temperature and pH values. The primary optimized values of pH and temperature for best-loaded amount of DOX were 8.9 and 309 K, respectively. Moreover, we found that the smallest amount of released DOX, in pH of cancer microenvironment (5.4), occurs when DOX had been previously loaded in pH 7.8 and 310 K. Although the highest amount of loaded DOX was in basic pH, the results of efficient release of DOX from the GO-DOX complex and also cellular toxicity assay revealed that the best pH for loading of DOX on GO was 7.8. Therefore, in addition to optimization of parameters for efficient loading of DOX on GO, this study suggested that normalization of a released drug compared with the amount of a loaded drug could be a new approach for optimization of drug loading on nanocarriers.

In vivo noninvasive analysis of graphene nanomaterial pharmacokinetics using photoacoustic flow cytometry.

Graphene-based nanomaterials (GBNs) are quickly revolutionizing modern electronics, energy generation and storage, clothing and biomedical devices. Due to GBN's variety of physical and chemical parameters that define their toxicity and their aggregation in suspension, interpreting its toxicology without accurate information on graphene's distribution and behavior in live organisms is challenging. In this work, we present a laser-based optical detection methodology for noninvasive detection and pharmacokinetics analysis of GBNs directly in blood flow in mice using in vivo photoacoustic (PA) flow cytometry (PAFC). PAFC provides unique insight on how chemical modifications of GBNs affect their distribution in blood circulation and how quickly they are eliminated from the flow. Overall, PAFC provided unique data crucial for understanding GBN toxicity through real-time detection of GBNs using their intrinsic light absorption contrast. Copyright © 2017 John Wiley & Sons, Ltd.

Chronic exposure to graphene-based nanomaterials induces behavioral deficits and neural damage in Caenorhabditis elegans.

Nanomaterials of graphene and its derivatives have been widely applied in recent years, but whose impacts on the environment and health are still not well understood. In the present study, the potential adverse effects of graphite (G), graphite oxide nanoplatelets (GO) and graphene quantum dots (GQDs) on the motor nervous system were investigated using nematode Caenorhabditis elegans as the assay system. After being characterized using TEM, SEM, XPS and PLE, three nanomaterials were chronically exposed to C. elegans for 6 days. In total, 50-100 mg l-1 GO caused a significant reduction in the survival rate, but G and GDDs showed low lethality on nematodes. After chronic exposure of sub-lethal dosages, three nanomaterials were observed to distribute primarily in the pharynx and intestine; but GQDs were widespread in nematode body. Three graphene-based nanomaterials resulted in significant declines in locomotor frequency of body bending, head thrashing and pharynx pumping. In addition, mean speed, bending angle-frequency and wavelength of the crawling movement were significantly reduced after exposure. Using transgenic nematodes, we found high concentrations of graphene-based nanomaterials induced down-expression of dat-1::GFP and eat-4::GFP, but no significant changes in unc-47::GFP. This indicates that graphene-based nanomaterials can lead to damages in the dopaminergic and glutamatergic neurons. The present data suggest that chronic exposure of graphene-based nanomaterials may cause neurotoxicity risks of inducing behavioral deficits and neural damage. These findings provide useful information to understand the toxicity and safe application of graphene-based nanomaterials. Copyright © 2017 John Wiley & Sons, Ltd.

Biodistribution and toxicity of radio-labeled few layer graphene in mice after intratracheal instillation.

BACKGROUND: The potential human health risks from graphene inhalation exposure have attracted substantial scientific interest as a result of the numerous exciting potential commercial applications of graphene. However, the long-term distribution of graphene in organisms after inhalation is unknown, largely as a result of challenges associated with accurate graphene quantification. METHODS: Carbon-14 labeled FLG was used to quantify the in vivo distribution of FLG in mice after oral gavage or intratracheal instillation for up to 3 or 28 days after exposure, respectively. RESULTS: Intratracheally instilled FLG was mainly retained in the lung with 47% remaining after 4 weeks. Exposure to non-labeled FLG resulted in dose-dependent acute lung injury and pulmonary edema, but these effects were alleviated with time despite the continued presence of FLG in the lungs. One percent and 0.18% of the intratracheally instilled FLG was present in the liver and spleen, respectively, after 14 days by passing through the air-blood barrier, a finding supported by the results of oral gavage experiments which did not show detectable absorption through the gastrointestinal tract. In addition, 46.2% of the intratracheally instilled FLG was excreted through the feces 28 d after exposure. CONCLUSIONS: Quantitative measurements revealed the elimination mechanism for FLG and its biodistribution for two exposure pathways. Graphene persistence in the lung only caused transient pulmonary effects. The in vivo distribution, elimination, and toxicity results provided here measured using a robust quantitative method support the human health risk assessment of graphene.

Reduced graphene oxide: nanotoxicological profile in rats.

BACKGROUND: We have previously demonstrated that reduced graphene oxide (rGO) administered intravenously in rats was detected inside the hippocampus after downregulation of the tight and adherens junction proteins of the blood-brain barrier. While down-regulators of junctional proteins could be useful tools for drug delivery through the paracellular pathway, concerns over toxicity must be investigated before clinical application. Herein, our purpose was to trace whether the rGO inside the hippocampus triggered toxic alterations in this brain region and in target organs (blood, liver and kidney) of rats at various time points (15 min, 1, 3 h and 7 days). RESULTS: The assessed rGO-treated rats (7 mg/kg) were clinically indistinguishable from controls at all the time points. Hematological, histopathological (neurons and astrocytes markers), biochemical (nephrotoxicity and hepatotoxicity assessment) and genotoxicological based tests showed that systemic rGO single injection seemed to produce minimal toxicological effects at the time points assessed. Relative to control, the only change was a decrease in the blood urea nitrogen level 3 h post-treatment and increases in superoxide dismutase activity 1 h and 7 days post-treatment. While no alteration in leukocyte parameters was detected between control and rGO-treated animals, time-dependent leukocytosis (rGO-1 h versus rGO-3 h) and leukopenia (rGO-3 h versus rGO-7 days) was observed intra-treated groups. Nevertheless, no inflammatory response was induced in serum and hippocampus at any time. CONCLUSIONS: The toxic effects seemed to be peripheral and transitory in the short-term analysis after systemic administration of rGO. The effects were self-limited and non-significant even at 7 days post-rGO administration.

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.

In Vitro and In Vivo Tumor Targeted Photothermal Cancer Therapy Using Functionalized Graphene Nanoparticles.

Despite the tremendous progress that photothermal therapy (PTT) has recently achieved, it still has a long way to go to gain the effective targeted photothermal ablation of tumor cells. Driven by this need, we describe a new class of targeted photothermal therapeutic agents for cancer cells with pH responsive bioimaging using near-infrared dye (NIR) IR825, conjugated poly(ethylene glycol)-g-poly(dimethylaminoethyl methacrylate) (PEG-g-PDMA, PgP), and hyaluronic acid (HA) anchored reduced graphene oxide (rGO) hybrid nanoparticles. The obtained rGO nanoparticles (PgP/HA-rGO) showed pH-dependent fluorescence emission and excellent near-infrared (NIR) irradiation of cancer cells targeted in vitro to provide cytotoxicity. Using intravenously administered PTT agents, the time-dependent in vivo tumor target accumulation was exactly defined, presenting eminent photothermal conversion at 4 and 8 h post-injection, which was demonstrated from the ex vivo biodistribution of tumors. These tumor environment responsive hybrid nanoparticles generated photothermal heat, which caused dominant suppression of tumor growth. The histopathological studies obtained by H&E staining demonstrated complete healing from malignant tumor. In an area of limited successes in cancer therapy, our translation will pave the road to design stimulus environment responsive targeted PTT agents for the safe eradication of devastating cancer.

Accumulation and toxicity of intravenously-injected functionalized graphene oxide in mice.

Graphene and its functionalized derivatives have recently emerged as interesting nanomaterials with promising applications in biomedicine. In this study, the long-term in vivo biodistribution of intravenously injected nanographene oxide (NGO) functionalized with poly sodium 4-styrenesulfonate (PSS) was systematically examined and the potential toxicity over 6 months of NGO-PSS nanoparticles was investigated. Our results showed that the nanoparticles mainly accumulate in the lung, liver and spleen, where they persist for at least 6 months. These nanoparticles result in acute liver injury and chronic inflammation of the lung, liver and spleen, as evidenced by blood biochemistry results and histological examinations.