Dental implant failure possibly attributed to embedded pencil graphite: first clinical report.

Implant failures have been associated with a diversity of etiologic processes, predominately arising from bone loss (peri-implantitis) due to inadequate maintenance of oral hygiene or excess luting agents. The aim of this article is to report a novel case of the apparent failure of a dental implant to undergo osseointegration in the presence of submerged pencil graphite. Practitioners are advised to carefully evaluate the clinical and radiographic site of a proposed implant for occult foreign substances. Embedded pencil graphite in the jawbone may promote a foreign body reaction and should be considered in the list of possible contributing factors to dental implant complications.

Case study: risk associated to wearing silver or graphene nanoparticle-coated facemasks for protection against COVID-19.

The world is living a pandemic situation derived from the worldwide spreading of SARS-CoV-2 virus causing COVID-19. Facemasks have proven to be one of the most effective prophylactic measures to avoid the infection that has made that wearing of facemasks has become mandatory in most of the developed countries. Silver and graphene nanoparticles have proven to have antimicrobial properties and are used as coating of these facemasks to increase the effectivity of the textile fibres. In the case of silver nanoparticles, we have estimated that in a real scenario the systemic (internal) exposure derived from wearing these silver nanoparticle facemasks would be between 7.0 × 10-5 and 2.8 × 10-4 mg/kg bw/day. In addition, we estimated conservative systemic no effect levels between 0.075 and 0.01 mg/kg bw/day. Therefore, we estimate that the chronic exposure to silver nanoparticles derived form facemasks wearing is safe. In the case of graphene, we detected important gaps in the database, especially regarding toxicokinetics, which prevents the derivation of a systemic no effect level. Nevertheless, the qualitative approach suggests that the risk of dermal repeated exposure to graphene is very low, or even negligible. We estimated that for both nanomaterials, the risk of skin sensitisation and genotoxicity is also negligible.

Graphene Family Nanomaterials in Ocular Applications: Physicochemical Properties and Toxicity.

Graphene family nanomaterials (GFNs) are rapidly emerging for ocular applications due to their outstanding physicochemical properties. Since the eyes are very sensitive organs and the contact between the eyes and GFNs in eye drops, contact lenses, intraocular drug delivery systems and biosensors and even the workers handling these nanomaterials is inevitable, it is necessary to investigate their ocular toxicities and physiological interactions with cells as well as their toxicity mechanisms. The toxicity of GFNs can be extremely affected by their physicochemical properties, including composition, size, surface chemistry, and oxidation level as well as dose and the time of exposure. Up to now, there are several studies on the in vitro and in vivo toxicity of GFNs; however, a comprehensive review on ocular toxicity and applications of GFNs is missing, and a knowledge about the health risks of eye exposure to the GFNs is predominantly unspecified. This review highlights the ocular applications of GFNs and systematically covers the most recent advances of GFNs' physicochemical properties, in vitro and in vivo ocular toxicity, and the possible toxicity mechanisms as well as provides some perspectives on the potential risks of GFNs in material development and biomedical applications.

Investigating biological effects of multidimensional carboxylated carbon-based nanomaterials on human lung A549 cells revealed via non-targeted metabolomics approach.

The biological responses of multidimensional carboxylated carbon-based nanomaterials (c-CBNs), including carboxylated graphene, carbon nanotube, and fullerene, on human lung A549 cells were investigated by using metabolomics technology. The structure and components of c-CBNs were characterized, and their biological effects were evaluated through cell apoptosis and viability analysis. Additionally, the metabolomics analysis of the nanomaterial-cell interaction system was performed using the established platform combining liquid chromatography-mass spectrometry (LC-MS) with the bioinformatics system. Results revealed that all tested c-CBNs demonstrated some biological effects in our cell model. However, significant metabolomic alterations induced by c-CBNs were also observed mainly in amino acids, organic acids, glycerophospholipids, and glycerolipids. Further, under the tested concentrations, the multiple dimensions of c-CBNs played a major role in determining the metabolic process in various interaction modes. This study provides an advanced alternative for evaluating metabolic effects of multidimensional nanomaterials through metabolomics technology considering the association between dimension and metabolic characteristics.

Unravelling the Potential of Graphene Quantum Dots in Biomedicine and Neuroscience.

Quantum dots (QDs) are semiconducting nanoparticles that have been gaining ground in various applications, including the biomedical field, thanks to their unique optical properties. Recently, graphene quantum dots (GQDs) have earned attention in biomedicine and nanomedicine, thanks to their higher biocompatibility and low cytotoxicity compared to other QDs. GQDs share the optical properties of QD and have proven ability to cross the blood-brain barrier (BBB). For this reason, GQDs are now being employed to deepen our knowledge in neuroscience diagnostics and therapeutics. Their size and surface chemistry that ease the loading of chemotherapeutic drugs, makes them ideal drug delivery systems through the bloodstream, across the BBB, up to the brain. GQDs-based neuroimaging techniques and theranostic applications, such as photothermal and photodynamic therapy alone or in combination with chemotherapy, have been designed. In this review, optical properties and biocompatibility of GQDs will be described. Then, the ability of GQDs to overtake the BBB and reach the brain will be discussed. At last, applications of GQDs in bioimaging, photophysical therapies and drug delivery to the central nervous system will be considered, unraveling their potential in the neuroscientific field.

Improved Biocompatibility of Amino-Functionalized Graphene Oxide in Caenorhabditis elegans.

Graphene oxide (GO) holds high promise for diagnostic and therapeutic applications in nanomedicine but reportedly displays immunotoxicity, underlining the need for developing functionalized GO with improved biocompatibility. This study describes adverse effects of GO and amino-functionalized GO (GONH2 ) during Caenorhabditis elegans development and ageing upon acute or chronic exposure. Chronic GO treatment throughout the C. elegans development causes decreased fecundity and a reduction of animal size, while acute treatment does not lead to any measurable physiological decline. However, RNA-Sequencing data reveal that acute GO exposure induces innate immune gene expression. The p38 MAP kinase, PMK-1, which is a well-established master regulator of innate immunity, protects C. elegans from chronic GO toxicity, as pmk-1 mutants show reduced tissue-functionality and facultative vivipary. In a direct comparison, GONH2 exposure does not cause detrimental effects in the wild type or in pmk-1 mutants, and the innate immune response is considerably less pronounced. This work establishes enhanced biocompatibility of amino-functionalized GO in a whole-organism, emphasizing its potential as a biomedical nanomaterial.

Graphene materials as 2D non-viral gene transfer vector platforms.

Advances in genomics and gene therapy could offer solutions to many diseases that remain incurable today, however, one of the critical reasons halting clinical progress is due to the difficulty in designing efficient and safe delivery vectors for the appropriate genetic cargo. Safety and large-scale production concerns counter-balance the high gene transfer efficiency achieved with viral vectors, while non-viral strategies have yet to become sufficiently efficient. The extraordinary physicochemical, optical and photothermal properties of graphene-based materials (GBMs) could offer two-dimensional components for the design of nucleic acid carrier systems. We discuss here such properties and their implications for the optimization of gene delivery. While the design of such vectors is still in its infancy, we provide here an exhaustive and up-to-date analysis of the studies that have explored GBMs as gene transfer vectors, focusing on the functionalization strategies followed to improve vector performance and on the biological effects attained.

Comparative in vitro toxicity of a graphene oxide-silver nanocomposite and the pristine counterparts toward macrophages.

BACKGROUND: Graphene oxide (GO) is a highly oxidized graphene form with oxygen functional groups on its surface. GO is an excellent platform to support and stabilize silver nanoparticles (AgNP), which gives rise to the graphene oxide-silver nanoparticle (GOAg) nanocomposite. Understanding how this nanocomposite interacts with cells is a toxicological challenge of great importance for future biomedical applications, and macrophage cells can provide information concerning the biocompatibility of these nanomaterials. The cytotoxicity of the GOAg nanocomposite, pristine GO, and pristine AgNP was compared toward two representative murine macrophages: a tumoral lineage (J774) and peritoneal macrophages collected from Balb/c mouse. The production of reactive oxygen species (ROS) by J774 macrophages was also monitored. We investigated the internalization of nanomaterials by transmission electron microscopy (TEM). The quantification of internalized silver was carried out by inductively coupled plasma mass spectrometry (ICP-MS). Nanomaterial stability in the cell media was investigated overtime by visual observation, inductively coupled plasma optical emission spectrometry (ICP OES), and dynamic light scattering (DLS). RESULTS: The GOAg nanocomposite was more toxic than pristine GO and pristine AgNP for both macrophages, and it significantly induced more ROS production compared to pristine AgNP. TEM analysis showed that GOAg was internalized by tumoral J774 macrophages. However, macrophages internalized approximately 60 % less GOAg than did pristine AgNP. The images also showed the degradation of nanocomposite inside cells. CONCLUSIONS: Although the GOAg nanocomposite was less internalized by the macrophage cells, it was more toxic than the pristine counterparts and induced remarkable oxidative stress. Our findings strongly reveal a synergistic toxicity effect of the GOAg nanocomposite. The toxicity and fate of nanocomposites in cells are some of the major concerns in the development of novel biocompatible materials and must be carefully evaluated.

An in vitro alveolar macrophage assay for predicting the short-term inhalation toxicity of nanomaterials.

BACKGROUND: Most in vitro studies investigating nanomaterial pulmonary toxicity poorly correlate to in vivo inhalation studies. Alveolar macrophages (AMs) play an outstanding role during inhalation exposure since they effectively clear the alveoli from particles. This study addresses the applicability of an in vitro alveolar macrophage assay to distinguish biologically active from passive nanomaterials. METHODS: Rat NR8383 alveolar macrophages were exposed to 18 inorganic nanomaterials, covering AlOOH, BaSO4, CeO2, Fe2O3, TiO2, ZrO2, and ZnO NMs, amorphous SiO2 and graphite nanoplatelets, and two nanosized organic pigments. ZrO2 and amorphous SiO2 were tested without and with surface functionalization. Non-nanosized quartz DQ12 and corundum were used as positive and negative controls, respectively. The test materials were incubated with the cells in protein-free culture medium. Lactate dehydrogenase, glucuronidase, and tumour necrosis factor alpha were assessed after 16 h. In parallel, H2O2 was assessed after 1.5 h. Using the no-observed-adverse-effect concentrations (NOAECs) from available rat short-term inhalation studies (STIS), the test materials were categorized as active (NOAEC < 10 mg/m(3)) or passive. RESULTS: In vitro data reflected the STIS categorization if a particle surface area-based threshold of <6000 mm(2)/mL was used to determine the biological relevance of the lowest observed significant in vitro effects. Significant effects that were recorded above this threshold were assessed as resulting from test material-unspecific cellular 'overload'. Test materials were assessed as active if ≥2 of the 4 in vitro parameters undercut this threshold. They were assessed as passive if 0 or 1 parameter was altered. An overall assay accuracy of 95 % was achieved. CONCLUSIONS: The in vitro NR8383 alveolar macrophage assay allows distinguishing active from passive nanomaterials. Thereby, it allows determining whether in vivo short-term inhalation testing is necessary for hazard assessment. Results may also be used to group nanomaterials by biological activity. Further work should aim at validating the assay.

Exposure monitoring of graphene nanoplatelets manufacturing workplaces.

Graphenes have emerged as a highly promising, two-dimensional engineered nanomaterial that can possibly substitute carbon nanotubes. They are being explored in numerous R&D and industrial applications in laboratories across the globe, leading to possible human and environmental exposures to them. Yet, there are no published data on graphene exposures in occupational settings and no readily available methods for their detection and quantitation exist. This study investigates for the first time the potential exposure of workers and research personnel to graphenes in two research facilities and evaluates the status of the control measures. One facility manufactures graphene using graphite exfoliation and chemical vapor deposition (CVD), while the other facility grows graphene on a copper plate using CVD, which is then transferred to a polyethylene terephthalate (PET) sheet. Graphene exposures and process emissions were investigated for three tasks - CVD growth, exfoliation, and transfer - using a multi-metric approach, which utilizes several direct reading instruments, integrated sampling, and chemical and morphological analysis. Real-time instruments included a dust monitor, condensation particle counter (CPC), nanoparticle surface area monitor, scanning mobility particle sizer, and an aethalometer. Morphologically, graphenes and other nanostructures released from the work process were investigated using a transmission electron microscope (TEM). Graphenes were quantified in airborne respirable samples as elemental carbon via thermo-optical analysis. The mass concentrations of total suspended particulate at Workplaces A and B were very low, and elemental carbon concentrations were mostly below the detection limit, indicating very low exposure to graphene or any other particles. The real-time monitoring, especially the aethalometer, showed a good response to the released black carbon, providing a signature of the graphene released during the opening of the CVD reactor at Workplace A. The TEM observation of the samples obtained from Workplaces A and B showed graphene-like structures and aggregated/agglomerated carbon structures. Taken together, the current findings on common scenarios (exfoliation, CVD growth, and transfer), while not inclusive of all graphene manufacturing processes, indicate very minimal graphene or particle exposure at facilities manufacturing graphenes with good manufacturing practices.

Inhibition of Viability of the Respiratory Epithelial Cells Using Functionalized Graphene Oxide.

The viability of A549 cells, a human lung carcinoma epithelial cell line, was evaluated after exposure to graphene oxide (GO) and its derivatives (dodecylamine GO (DA-GO), reduced GO (rGO), and sodium dodecyl sulfate rGO (SDS-rGO)). A decrease in the relative amounts of C-OH bonds and an increase in the number of C-C and C-N bonds in the C 1s spectra indicated that the reduction of GO to rGO and the surface functionalization of GO has taken place. The appearance of amine stretching bands, out-of-plane C-H stretching vibrations, and S = O stretching bands in the infrared spectra indicated the formation of DA-GO, rGO, and SDS-rGO, respectively. Low concentrations (3-25 µg/mL) of GO, rGO, and SDS-rGO were found to be mildly toxic, whereas DA-GO exhibited severe dose-dependent toxicity over the same concentration range. High concen- trations (50-400 µg/mL) of GO and all its derivatives resulted in severe toxicity to the A549 cells. It is believed that surface functionality strongly affects the viability of A549 cells.

Delivery of a therapeutic protein for bone regeneration from a substrate coated with graphene oxide.

The therapeutic efficacy of drugs often depends on the drug delivery carrier. For efficient delivery of therapeutic proteins, delivery carriers should enable the loading of large doses, sustained release, and retention of the bioactivity of the therapeutic proteins. Here, it is demonstrated that graphene oxide (GO) is an efficient carrier for delivery of therapeutic proteins. Titanium (Ti) substrates are coated with GO through layer-by-layer assembly of positively (GO-NH3⁺) and negatively (GO-COO⁻) charged GO sheets. Subsequently, a therapeutic protein (bone morphogenetic protein-2, BMP-2) is loaded on the GO-coated Ti substrate with the outermost coating layer of GO-COO⁻ (Ti/GO⁻). The GO coating on Ti substrate enables loading of large doses and the sustained release of BMP-2 with preservation of the structure and bioactivity of the drug. The extent of in vitro osteogenic differentiation of human bone marrow-derived mesenchymal stem cells is higher when they are cultured on Ti/GO- carrying BMP-2 than when they are cultured on Ti with BMP-2. Eight weeks after implantation in mouse models of calvarial defects, the Ti/GO-/BMP-2 implants show more robust new bone formation compared with Ti, Ti/GO-, or Ti/BMP-2 implants. Therefore, GO is an effective carrier for the controlled delivery of therapeutic proteins, such as BMP-2, which promotes osteointegration of orthopedic or dental Ti implants.

Hemocompatibility and macrophage response of pristine and functionalized graphene.

Graphene and its derivatives are being proposed for several important biomedical applications including drug delivery, gene delivery, contrast imaging, and anticancer therapy. Most of these applications demand intravenous injection of graphene and hence evaluation of its hemocompatibility is an essential prerequisite. Herein, both pristine and functionalized graphene are extensively characterized for their interactions with murine macrophage RAW 264.7 cells and human primary blood components. Detailed analyses of the potential uptake by macrophages, effects on its metabolic activity, membrane integrity, induction of reactive oxygen stress, hemolysis, platelet activation, platelet aggregation, coagulation cascade, cytokine induction, immune cell activation, and immune cell suppression are performed using optimized protocols for nanotoxicity evaluation. Electron microscopy, confocal Raman spectral mapping, and confocal fluorescence imaging studies show active interaction of both the graphene systems with macrophage cells, and the reactive oxygen species mediated toxicity effects of hydrophobic pristine samples are significantly reduced by surface functionalization. In the case of hemocompatibility, both types of graphene show excellent compatibility with red blood cells, platelets, and plasma coagulation pathways, and minimal alteration in the cytokine expression by human peripheral blood mononuclear cells. Further, both samples do not cause any premature immune cell activation or suppression up to a relatively high concentration of 75 µg mL(-1) after 72 h of incubation under in vitro conditions. This study clearly suggests that the observed toxicity effects of pristine graphene towards macrophage cells can be easily averted by surface functionalization and both the systems show excellent hemocompatibility.

Restoring basal planes of graphene oxides for highly efficient loading and delivery of ß-lapachone.

An efficient and biocompatible drug nanocarrier is essential for nanomedicines to realize their full therapeutic potential. Here, we investigate the loading of a selective and potent anticancer drug, ß-lapachone (ß-lap), on a magnetite nanoparticle-decorated reduced graphene oxide (Fe(3)O(4)/rGO) and the in vitro anticancer efficacy of ß-lap loaded Fe(3)O(4)/rGO. Reduced graphene oxide (rGO) with magnetic functionality was prepared via electrostatic interaction between positively charged magnetite (Fe(3)O(4)) nanoparticles and negatively charged GO, followed by hydrazine reduction of GO to rGO. The prepared Fe(3)O(4)/rGO shows that Fe(3)O(4) makes the Fe(3)O(4)/rGO hybrid magnetically separable for easy handling during drug loading and release and the Fe(3)O(4)/rGO hybrid exhibits significantly higher loading capacity than that of Fe(3)O(4)/GO, suggesting that restoration of the graphene basal plane upon reduction of GO enhances the interaction between ß-lap and rGO. Cellular uptake studies using fluorescently labeled Fe(3)O(4)/rGO verifies successful internalization of Fe(3)O(4)/rGO into the cytoplasm while rGO without hybridized Fe(3)O(4) has poor uptake performance. Furthermore, ß-lap loaded Fe(3)O(4)/rGO shows remarkably high cytotoxicity toward MCF-7 breast cancer cells while the blank Fe(3)O(4)/rGO produces no cytotoxic effects. The cytotoxicity results suggest that Fe(3)O(4)/rGO is an efficient drug carrier for anticancer treatments. The fine-tuning of the chemical structures of graphene oxides by reduction chemistry may provide a universal route for controlled loading and release of drugs or biomolecules to construct advanced delivery vehicles.

Pigmented orbital mass due to remote pencil trauma.

A 45-year-old woman with a medial canthal mass associated with new-onset epiphora was found to have a darkly pigmented mass arising from the lacrimal sac wall because of intranasal pencil trauma 40 years before. Resection of the graphite-induced granuloma with dacryocystorhinostomy was curative.

[Evidence-based medicine in evaluating occupational health risk in workers engaged into graphite ware production].

The article deals with results of epidemiologic study on evaluating the health state of workers engaged into graphite ware production, through three various parameters based on data about chronic non-occupational diseases. The authors evaluate carcinogenic risk for the population residing on various distances from the enterprise.

Graphene oxide disrupted mitochondrial homeostasis through inducing intracellular redox deviation and autophagy-lysosomal network dysfunction in SH-SY5Y cells.

Graphene oxide (GO) nanomaterials have significant advantages for drug delivery and electrode materials in neural science, however, their exposure risks to the central nervous system (CNS) and toxicity concerns are also increased. The current studies of GO-induced neurotoxicity remain still ambiguous, let alone the mechanism of how complicated GO chemistry affects its biological behavior with neural cells. In this study, we characterized the commercially available GO in detail and investigated its biological adverse effects using cultured SH-SY5Y cells. We found that ultrasonic processing in medium changed the oxidation status and surface reactivity on the planar surface of GO due to its hydration activity, causing lipid peroxidation and cell membrane damage. Subsequently, ROS-disrupted mitochondrial homeostasis, resulting from the activation of NOX2 signaling, was observed following GO internalization. The autophagy-lysosomal network was initiated as a defensive reaction to obliterate oxidative damaged mitochondria and foreign nanomaterials, which was ineffective due to reduced lysosomal degradation capacity. These sequential cellular responses exacerbated mitochondrial stress, leading to apoptotic cell death. These data highlight the importance of the structure-related activity of GO on its biological properties and provide an in-depth understanding of how GO-derived cellular redox signaling induces mitochondrion-related cascades that modulate cell functionality and survival.

Graphene oxide aggravated dextran sulfate sodium-induced colitis through intestinal epithelial cells autophagy dysfunction.

Graphene oxide (GO) is one of the most promising nanomaterials used in biomedicine. However, studies about its adverse effects on the intestine in state of inflammation remain limited. This study aimed to explore the underlying effects of GO on intestinal epithelial cells (IECs) in vitro and colitis in vivo. We found that GO could exert toxic effects on NCM460 cells in a dose- and time-dependent manner and promote inflammation. Furthermore, GO caused lysosomal dysfunction and then blockaded autophagy flux. Moreover, pharmacological autophagy inhibitor 3-Methyladenine could reverse GO-induced LC3B and p62 expression levels, reduce expression levels of IL-6, IL-8, TLR4, and CXCL2, and increase the level of IL-10. In vivo, C57BL/6 mice were treated with 2.5% dextran sulfate sodium (DSS) in drinking water for five consecutive days to induce colitis. Then, GO at 60 mg/kg dose was administered through the oral route every two days from day 2 to day 8. These results showed that GO aggravated DSS-induced colitis, characterized by shortening of the colon and severe pathological changes, and induced autophagy. In conclusion, GO caused the abnormal autophagy in IECs and exacerbated DSS-induced colitis in mice. Our research indicated that GO may contribute to the development of intestinal inflammation by inducing IECs autophagy dysfunction.

Enhanced Hemocompatibility of a Direct Chemical Vapor Deposition-Derived Graphene Film.

A wide range of biomedical devices are being used to treat cardiovascular diseases, and thus they routinely come into contact with blood. Insufficient hemocompatibility has been found to impair the functionality and safety of these devices through the activation of blood coagulation and the immune system. Numerous attempts have been made to develop surface modification approaches of the cardiovascular devices to improve their hemocompatibility. However, there are still no ideal "blood-friendly" coating materials, which possess the desired hemocompatibility, tissue compatibility, and mechanical properties. As a novel multifunctional material, graphene has been proposed for a wide range of biomedical applications. The chemical inertness, atomic smoothness, and high durability make graphene an ideal candidate as a surface coating material for implantable devices. Here, we evaluated the hemocompatibility of a graphene film prepared on quartz glasses (Gra-glasses) from a direct chemical vapor deposition process. We found that the graphene coating, which is free of transfer-mediating polymer contamination, significantly suppressed platelet adhesion and activation, prolonged coagulation time, and reduced ex vivo thrombosis formation. We attribute the excellent antithrombogenic properties of the Gra-glasses to the low surface roughness, low surface energy (especially the low polar component of the surface energy), and the negative surface charge of the graphene film. Given these excellent hemocompatible properties, along with its chemical inertness, high durability, and molecular impermeability, a graphene film holds great promise as an antithrombogenic coating for next-generation cardiovascular devices.