Graphene-based nanomaterials for nanobiotechnology and biomedical applications

Nanomaterials, Autophagy, and Lupus Disease

Nanoscale materials hold great promise in the therapeutic field. In particular, as carriers or vectors, they help bioactive molecules reach their primary targets. Furthermore, by themselves, certain nanomaterials-regarded as protective-can modulate particular metabolic pathways that are deregulated in pathological situations. They can also synergistically improve the effects of a payload drug. These properties are the basis of their appeal. However, nanoscale materials can also have intrinsic properties that limit their use, and this is the case for certain types of nanomaterials that influence autophagy. This property can be beneficial in some pathological settings, but in others, if the autophagic flux is already accelerated, it can be deleterious. This is notably the case for systemic lupus erythematosus (SLE) and other chronic inflammatory diseases, including certain neurological diseases. The nanomaterial-autophagy interaction therefore must be treated with caution for therapeutic molecules and peptides that require vectorization for their administration.

Tissue distribution and urinary excretion of intravenously administered chemically functionalized graphene oxide sheets

The design of graphene-based materials for biomedical purposes is of great interest. Graphene oxide (GO) sheets represent the most widespread type of graphene materials in biological investigations. In this work, thin GO sheets were synthesized and further chemically functionalized with DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), a stable radiometal chelating agent, by an epoxide opening reaction. We report the tissue distribution of the functionalized GO sheets labeled with radioactive indium (111In) after intravenous administration in mice. Whole body single photon emission computed tomography (SPECT/CT) imaging, gamma counting studies, Raman microscopy and histological investigations indicated extensive urinary excretion and predominantly spleen accumulation. Intact GO sheets were detected in the urine of injected mice by Raman spectroscopy, high resolution transmission electron microscopy (HR-TEM) and electron diffraction. These results offer a previously unavailable pharmacological understanding on how chemically functionalized GO sheets transport in the blood stream and interact with physiological barriers that will determine their body excretion and tissue accumulation.

Multifunctional carbon nanomaterial hybrids for magnetic manipulation and targeting

Nanosized materials and multifunctional nanoscale platforms have attracted in the last years considerable interest in a variety of different fields including biomedicine. Carbon nanotubes and graphene are some of the most widely used carbon nanomaterials (CNMs) due to their unique morphology and structure and their characteristic physicochemical properties. Their high surface area allows efficient drug loading and bioconjugation and makes them the ideal platforms for decoration with magnetic nanoparticles (MNPs). In the biomedical area, MNPs are of particular importance due to their broad range of potential applications in drug delivery, non-invasive tumor imaging and early detection based on their optical and magnetic properties. The remarkable characteristics of CNMs and MNPs can be combined leading to CNM/MNP hybrids which offer numerous promising, desirable and strikingly advantageous properties for improved performance in comparison to the use of either material alone. In this minireview, we attempt to comprehensively report the most recent advances made with CNMs conjugated to different types of MNPs for magnetic targeting, magnetic manipulation, capture and separation of cells towards development of magnetic carbon-based devices.

Impact of graphene oxide on viability of Chinese hamster ovary and mouse hepatoma MH-22A cells

The evaluation of the cyto- and bio-compatibility is a critical step in the development of graphene oxide (GO) as a new promising material for in vivo biomedical applications. In this study, we report the impact of GO, with and without the addition of bovine serum albumin, on healthy (Chinese hamster ovary) and a cancer (mouse hepatoma MH-22A) cells viability and the estimation of the intracellular distribution of GO inside the cells in vitro. The viability tests were performed using a colony formation assay. The intracellular distribution of GO was estimated using Raman spectroscopy and imaging. The viability of both cell lines decreased with increasing concentration of graphene oxide (12.5-50.0 μg/ml): in the case of Chinese hamster ovary cells viability decreased from 44% to 11%, in the case of mouse hepatoma MH-22A cells--from 22% to 3%. These cell lines significantly differed in their response to GO and GO-BSA formulations. The results of viability tests correlate with results of atomic force microscopy and Raman spectroscopy and imaging findings. The GO influence on cell morphology changes, cell structure, cells colony growth dynamics and GO accumulation inside the cells was higher in the case of mouse hepatoma MH-22A cells.

Killing dental pathogens using antibacterial graphene oxide

Dental caries and periodontal diseases have a close relationship with microbes such as Streptococcus mutans, Porphyromonas gingivalis and Fusobacterium nucleatum. Graphene oxide (GO), as the derivative of graphene, plays an important role in many areas including biology and medicine. In particular, it has been known as a promising antimicrobial nanomaterial. In this study, we focused on the antimicrobial property of GO against dental pathogens. With the utilization of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduced test, colony forming units (CFU) counting, growth curve observation, live/dead fluorescent staining, and confocal laser scanning microscopy (CLSM), we found GO nanosheets were highly effective in inhibiting the growth of dental pathogens. Transmission electron microscopy (TEM) images revealed that the cell wall and membrane of bacteria lost their integrity and the intracellular contents leaked out after they were treated by GO. Therefore, GO nanosheets would be an effective antibacterial material against dental pathogens and the potential applications in dental care and therapy are promising.

Mechanisms of graphyne-enabled cholesterol extraction from protein clusters

Functionalized graphyne provides a novel vehicle for cholesterol removal from protein clusters by molecular dynamics simulations.

The perception of nanotechnology and nanomedicine: a worldwide social media study

We explore at a world level the awareness of nanotechnology expressed through the most popular online social media: Facebook. We aimed at identifying future trends, the most interested countries and the public perception of ethics, funding and economic issues. We found that graphene and carbon nanotubes are the most followed nanomaterials. Our poll showed that the continents with the most interest are Asia and Africa. A total of 43% would like to have a world commission regulating nanomedicine. In addition, 43% would give priority to theranostics. Over 90% believe that nanomedicine has an economic impact. Finally, we observed that the continents of living and origin of poll contributors correlated with ethic and funding opinions. This study highlights the potential of online social media to influence scientific communities, grant committees and nanotechnology companies, spreading nanotechnology awareness in emerging countries and among new generations.

Graphene-based nanobiocatalytic systems: recent advances and future prospects

Graphene-based nanomaterials are particularly useful nanostructured materials that show great promise in biotechnology and biomedicine. Owing to their unique structural features, exceptional chemical, electrical, and mechanical properties, and their ability to affect the microenvironment of biomolecules, graphene-based nanomaterials are suitable for use in various applications, such as immobilization of enzymes. We present the current advances in research on graphene-based nanomaterials used as novel scaffolds to build robust nanobiocatalytic systems. Their catalytic behavior is affected by the nature of enzyme-nanomaterial interactions and, thus, the availability of methods to couple enzymes with nanomaterials is an important issue. We discuss the implications of such interactions along with future prospects and possible challenges in this rapidly developing area.

An in vitro evaluation of graphene oxide reduced by Ganoderma spp. in human breast cancer cells (MDA-MB-231)

BACKGROUND

Recently, graphene and graphene-related materials have attracted much attention due their unique properties, such as their physical, chemical, and biocompatibility properties. This study aimed to determine the cytotoxic effects of graphene oxide (GO) that is reduced biologically using Ganoderma spp. mushroom extracts in MDA-MB-231 human breast cancer cells.

METHODS

Herein, we describe a facile and green method for the reduction of GO using extracts of Ganoderma spp. as a reducing agent. GO was reduced without any hazardous chemicals in an aqueous solution, and the reduced GO was characterized using a range of analytical procedures. The Ganoderma extract (GE)-reduced GO (GE-rGO) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, dynamic light scattering, scanning electron microscopy, Raman spectroscopy, and atomic force microscopy. Furthermore, the toxicity of GE-rGO was evaluated using a sequence of assays such as cell viability, lactate dehydrogenase leakage, and reactive oxygen species generation in human breast cancer cells (MDA-MB-231).

RESULTS

The preliminary characterization of reduction of GO was confirmed by the red-shifting of the absorption peak for GE-rGO to 265 nm from 230 nm. The size of GO and GE-rGO was found to be 1,880 and 3,200 nm, respectively. X-ray diffraction results confirmed that reduction processes of GO and the processes of removing intercalated water molecules and the oxide groups. The surface functionalities and chemical natures of GO and GE-rGO were confirmed using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface morphologies of the synthesized graphene were analyzed using high-resolution scanning electron microscopy. Raman spectroscopy revealed single- and multilayer properties of GE-rGO. Atomic force microscopy images provided evidence for the formation of graphene. Furthermore, the effect of GO and GE-rGO was examined using a series of assays, such as cell viability, membrane integrity, and reactive oxygen species generation, which are key molecules involved in apoptosis. The results obtained from cell viability and lactate dehydrogenase assay suggest that GO and GE-rGO cause dose-dependent toxicity in the cells. Interestingly, it was found that biologically derived GE-rGO is more toxic to cancer cells than GO.

CONCLUSION

We describe a simple, green, nontoxic, and cost-effective approach to producing graphene using mushroom extract as a reducing and stabilizing agent. The proposed method could enable synthesis of graphene with potential biological and biomedical applications such as in cancer and angiogenic disorders. To our knowledge, this is the first report using mushroom extract as a reducing agent for the synthesis of graphene. Mushroom extract can be used as a biocatalyst for the production of graphene.

Carbon nanomaterials as new tools for immunotherapeutic applications

The possibility to exploit carbon-based nanostructures such as carbon nanotubes and graphene as immunotherapeutic agents has interesting future prospects. In particular, their applications for anticancer treatment, imaging and vaccine development, together with their immunomodulator properties are highlighted.