Dispersibility-Dependent Biodegradation of Graphene Oxide by Myeloperoxidase

Environmental and Health Impacts of Graphene and Other Two-Dimensional Materials: A Graphene Flagship Perspective

Two-dimensional (2D) materials have attracted tremendous interest ever since the isolation of atomically thin sheets of graphene in 2004 due to the specific and versatile properties of these materials. However, the increasing production and use of 2D materials necessitate a thorough evaluation of the potential impact on human health and the environment. Furthermore, harmonized test protocols are needed with which to assess the safety of 2D materials. The Graphene Flagship project (2013-2023), funded by the European Commission, addressed the identification of the possible hazard of graphene-based materials as well as emerging 2D materials including transition metal dichalcogenides, hexagonal boron nitride, and others. Additionally, so-called green chemistry approaches were explored to achieve the goal of a safe and sustainable production and use of this fascinating family of nanomaterials. The present review provides a compact survey of the findings and the lessons learned in the Graphene Flagship.

Progress and mechanism of graphene oxide-composited materials in application of peripheral nerve repair

Peripheral nerve injuries (PNI) are one of the most common nerve injuries, and graphene oxide (GO) has demonstrated significant potential in the treatment of PNI. GO could enhance the proliferation, adhesion, migration, and differentiation of neuronal cells by upregulating the expression of relevant proteins, and regulate the angiogenesis process and immune response. Therefore, GO is a suitable additional component for fabricating artificial nerve scaffolds (ANS), in which the slight addition of GO could improve the physicochemical performance of the matrix materials, through hydrogen bonds and electrostatic attraction. GO-composited ANS can increase the expression of nerve regeneration-associated genes and factors, promoting angiogenesis by activating the RAS/MAPK and AKT-eNOS-VEGF signaling pathway, respectively. Moreover, GO could be metabolized and excreted from the body through the pathway of peroxidase degradation in vivo. Consequently, the application of GO in PNI regeneration exhibits significant potential for transitioning from laboratory research to clinical use.

Interaction of graphene and WS2 with neutrophils and mesenchymal stem cells: implications for peripheral nerve regeneration

Graphene and bidimensional (2D) materials have been widely used in nerve conduits to boost peripheral nerve regeneration. Nevertheless, the experimental and commercial variability in graphene-based materials generates graphene forms with different structures and properties that can trigger entirely diverse biological responses from all the players involved in nerve repair. Herein, we focus on the graphene and tungsten disulfide (WS2) interaction with non-neuronal cell types involved in nerve tissue regeneration. We synthesize highly crystalline graphene and WS2 with scalable techniques such as thermal decomposition and chemical vapor deposition. The materials were able to trigger the activation of a neutrophil human model promoting Neutrophil Extracellular Traps (NETs) production, particularly under basal conditions, although neutrophils were not able to degrade graphene. Of note is that pristine graphene acts as a repellent for the NET adhesion, a beneficial property for nerve conduit long-term applications. Mesenchymal stem cells (MSCs) have been proposed as a promising strategy for nerve regeneration in combination with a conduit. Thus, the interaction of graphene with MSCs was also investigated, and reduced viability was observed only on specific graphene substrates. Overall, the results confirm the possibility of regulating the cell response by varying graphene properties and selecting the most suitable graphene forms.

Electrochemical impedance spectroscopy, another arrow in the arsenal to study the biodegradability of two-dimensional materials

Carbon nitride (C3N4) is an innovative material with a high potential in many applications including energy storage, catalysis, composites, and biomedicine. C3N4 appears remarkably interesting not only for its properties but also because its simple preparation routes involve low-cost starting materials and reagents. However, there is still a lack of information on its degradability. For this reason, in this study, we evaluate the environmental persistence of C3N4 and its oxidized form by applying the photo-Fenton reaction. The morphological and structural changes of both materials were monitored by transmission electron microscopy and Raman spectroscopy respectively. In addition, electrochemical impedance spectroscopy has been used as an original technique to validate the degradation process of C3N4.

ClO-driven degradation of graphene oxide: new insights from DFT calculations

We present an extensive investigation using density functional theory (DFT) calculations on various model graphene oxide (GO) nanostructures interacting with chlorine monoxide ClO, aiming to understand the role of this highly oxidizing species in C-C bond breakage and the formation of significant holes on GO sheets. During its function, the myeloperoxidase (MPO) enzyme abundantly generates chlorine-oxygen-containing species and their presence has been identified as the cause of degradation in carbon nanotubes of diverse sizes, morphologies, and chemical compositions, both in in vivo and in vitro samples. Notably, Kurapati et al. (Small, 2015, 11, 3985-3994) demonstrated efficient degradation of single GO monolayers through MPO catalysis, though the exact degradation mechanism remains unclear. In our study, we discover that breaking C-C bonds in a single graphene oxide sheet is achievable through a simple mechanism involving the dissociation of two ClO molecules that are chemically attached as nearest neighbor species but bonded to opposite sides of the GO layer (up/down configuration). Two new carbonyl oxygens appear on the surface and the Cl atoms can be transferred to the carbon layer or as physisorbed species near the GO surface. Relatively small energy barriers are associated with these molecular events. Continuing this process on neighboring sites leads to the presence of larger holes on the GO surface, accompanied by an increase in carbonyl species on the carbon network, consistent with X-ray photoelectron spectroscopy measurements. Indeed, the distribution of oxygen functionalities is found to be crucial in defining the damage pattern induced in the carbon layer. We emphasize the important role played by the local charge distribution in the stability or instability of chemical bonds, as well as in the energy barriers and reaction pathways. Finally, we explore the possibility of achieving chlorination of GO following MPO exposure. The here-reported predictions could be the root cause of the experimentally observed low stability of individual GO sheets during the MPO catalytic cycle.

Recent Advances in Biodegradable Green Electronic Materials and Sensor Applications

As environmental issues have become the dominant agenda worldwide, the necessity for more environmentally friendly electronics has recently emerged. Accordingly, biodegradable or nature-derived materials for green electronics have attracted increased interest. Initially, metal-green hybrid electronics are extensively studied. Although these materials are partially biodegradable, they have high utility owing to their metallic components. Subsequently, carbon-framed materials (such as graphite, cylindrical carbon nanomaterials, graphene, graphene oxide, laser-induced graphene) have been investigated. This has led to the adoption of various strategies for carbon-based materials, such as blending them with biodegradable materials. Moreover, various conductive polymers have been developed and researchers have studied their potential use in green electronics. Researchers have attempted to fabricate conductive polymer composites with high biodegradability by shortening the polymer chains. Furthermore, various physical, chemical, and biological sensors that are essential to modern society have been studied using biodegradable compounds. These recent advances in green electronics have paved the way toward their application in real life, providing a brighter future for society.

An Overview of the Potential of Food-Based Carbon Dots for Biomedical Applications

Food-based carbon dots (CDs) hold significant importance across various fields, ranging from biomedical applications to environmental and food industries. These CDs offer unique advantages over traditional carbon nanomaterials, including affordability, biodegradability, ease of operation, and multiple bioactivities. This work aims to provide a comprehensive overview of recent developments in food-based CDs, focusing on their characteristics, properties, therapeutic applications in biomedicine, and safety assessment methods. The review highlights the potential of food-based CDs in biomedical applications, including antibacterial, antifungal, antivirus, anticancer, and anti-immune hyperactivity. Furthermore, current strategies employed for evaluating the safety of food-based CDs have also been reported. In conclusion, this review offers valuable insights into their potential across diverse sectors and underscores the significance of safety assessment measures to facilitate their continued advancement and application.

Stabilization of Graphene Oxide Dispersion in Plasma-like Isotonic Solution Containing Aggregating Concentrations of Bivalent Cations

Graphene oxide's (GO) intravascular applications and biocompatibility are not fully explored yet, although it has been proposed as an anticancer drug transporter, antibacterial factor or component of wearable devices. Bivalent cations and the number of particles' atom layers, as well as their structural oxygen content and pH of the dispersion, all affect the GO size, shape, dispersibility and biological effects. Bovine serum albumin (BSA), an important blood plasma protein, is expected to improve GO dispersion stability in physiological concentrations of the precipitating calcium and magnesium cations to enable effective and safe tissue perfusion.

METHODS

Four types of GO commercially available aqueous dispersions (with different particle structures) were diluted, sonicated and studied in the presence of BSA and physiological cation concentrations. Nanoparticle populations sizes, electrical conductivity, zeta potential (Zetasizer NanoZS), structure (TEM and CryoTEM), functional groups content (micro titration) and dispersion pH were analyzed in consecutive preparation stages.

RESULTS

BSA effectively prevented the aggregation of GO in precipitating concentrations of physiological bivalent cations. The final polydispersity indexes were reduced from 0.66-0.91 to 0.36-0.43. The GO-containing isotonic dispersions were stable with the following Z-ave results: GO1 421.1 nm, GO2 382.6 nm, GO3 440.2 nm and GO4 490.1 nm. The GO behavior was structure-dependent.

CONCLUSION

BSA effectively stabilized four types of GO dispersions in an isotonic dispersion containing aggregating bivalent physiological cations.

Graphene-Based Material-Mediated Immunomodulation in Tissue Engineering and Regeneration: Mechanism and Significance

Tissue engineering and regenerative medicine hold promise for improving or even restoring the function of damaged organs. Graphene-based materials (GBMs) have become a key player in biomaterials applied to tissue engineering and regenerative medicine. A series of cellular and molecular events, which affect the outcome of tissue regeneration, occur after GBMs are implanted into the body. The immunomodulatory function of GBMs is considered to be a key factor influencing tissue regeneration. This review introduces the applications of GBMs in bone, neural, skin, and cardiovascular tissue engineering, emphasizing that the immunomodulatory functions of GBMs significantly improve tissue regeneration. This review focuses on summarizing and discussing the mechanisms by which GBMs mediate the sequential regulation of the innate immune cell inflammatory response. During the process of tissue healing, multiple immune responses, such as the inflammatory response, foreign body reaction, tissue fibrosis, and biodegradation of GBMs, are interrelated and influential. We discuss the regulation of these immune responses by GBMs, as well as the immune cells and related immunomodulatory mechanisms involved. Finally, we summarize the limitations in the immunomodulatory strategies of GBMs and ideas for optimizing GBM applications in tissue engineering. This review demonstrates the significance and related mechanism of the immunomodulatory function of GBM application in tissue engineering; more importantly, it contributes insights into the design of GBMs to enhance wound healing and tissue regeneration in tissue engineering.

Lung Persistence, Biodegradation, and Elimination of Graphene-Based Materials are Predominantly Size-Dependent and Mediated by Alveolar Phagocytes

Graphene-based materials (GBMs) have promising applications in various sectors, including pulmonary nanomedicine. Nevertheless, the influence of GBM physicochemical characteristics on their fate and impact in lung has not been thoroughly addressed. To fill this gap, the biological response, distribution, and bio-persistence of four different GBMs in mouse lungs up to 28 days after single oropharyngeal aspiration are investigated. None of the GBMs, varying in size (large versus small) and carbon to oxygen ratio as well as thickness (few-layers graphene (FLG) versus thin graphene oxide (GO)), induce a strong pulmonary immune response. However, recruited neutrophils internalize nanosheets better and degrade GBMs faster than macrophages, revealing their crucial role in the elimination of small GBMs. In contrast, large GO sheets induce more damages due to a hindered degradation and long-term persistence in macrophages. Overall, small dimensions appear to be a leading feature in the design of safe GBM pulmonary nanovectors due to an enhanced degradation in phagocytes and a faster clearance from the lungs for small GBMs. Thickness also plays an important role, since decreased material loading in alveolar phagocytes and faster elimination are found for FLGs compared to thinner GOs. These results are important for designing safer-by-design GBMs for biomedical application.

Plasma-Derived Fibrin Hydrogels Containing Graphene Oxide for Infections Treatment

Wound infection is inevitable in most patients suffering from extensive burns or chronic ulcers, and there is an urgent demand for the production of bactericidal dressings to be used as grafts to restore skin functionalities. In this context, the present study explores the fabrication of plasma-derived fibrin hydrogels containing bactericidal hybrids based on graphene oxide (GO). The hydrogels were fully characterized regarding gelation kinetics, mechanical properties, and internal hydrogel structures by disruptive cryo scanning electron microscopies (cryo-SEMs). The gelation kinetic experiments revealed an acceleration of the gel formation when GO was added to the hydrogels in a concentration of up to 0.2 mg/mL. The cryo-SEM studies showed up a decrease of the pore size when GO was added to the network, which agreed with a faster area contraction and a higher compression modulus of the hydrogels that contained GO, pointing out the critical structural role of the nanomaterial. Afterward, to study the bactericidal ability of the gels, GO was used as a carrier, loading streptomycin (STREP) on its surface. The loading content of the drug to form the hybrid (GO/STREP) resulted in 50.2% ± 4.7%, and the presence of the antibiotic was also demonstrated by Raman spectroscopy, Z-potential studies, and thermogravimetric analyses. The fibrin-derived hydrogels containing GO/STREP showed a dose-response behavior according to the bactericidal hybrid concentration and allowed a sustained release of the antibiotic at a programmed rate, leading to drug delivery over a prolonged period of time.

Graphene-Related Nanomaterials for Biomedical Applications

This paper builds on the context and recent progress on the control, reproducibility, and limitations of using graphene and graphene-related materials (GRMs) in biomedical applications. The review describes the human hazard assessment of GRMs in in vitro and in vivo studies, highlights the composition-structure-activity relationships that cause toxicity for these substances, and identifies the key parameters that determine the activation of their biological effects. GRMs are designed to offer the advantage of facilitating unique biomedical applications that impact different techniques in medicine, especially in neuroscience. Due to the increasing utilization of GRMs, there is a need to comprehensively assess the potential impact of these materials on human health. Various outcomes associated with GRMs, including biocompatibility, biodegradability, beneficial effects on cell proliferation, differentiation rates, apoptosis, necrosis, autophagy, oxidative stress, physical destruction, DNA damage, and inflammatory responses, have led to an increasing interest in these regenerative nanostructured materials. Considering the existence of graphene-related nanomaterials with different physicochemical properties, the materials are expected to exhibit unique modes of interactions with biomolecules, cells, and tissues depending on their size, chemical composition, and hydrophil-to-hydrophobe ratio. Understanding such interactions is crucial from two perspectives, namely, from the perspectives of their toxicity and biological uses. The main aim of this study is to assess and tune the diverse properties that must be considered when planning biomedical applications. These properties include flexibility, transparency, surface chemistry (hydrophil-hydrophobe ratio), thermoelectrical conductibility, loading and release capacity, and biocompatibility.

Surface Defects Regulate the in Vivo Bioenergetic Response of Earthworm Eisenia fetida Coelomocytes to Molybdenum Disulfide Nanosheets

Two-dimensional molybdenum disulfide (2D MoS₂) nanomaterials are seeing increased use in several areas, and this will lead to their inevitable release into soils. Surface defects can occur on MoS₂ nanosheets during synthesis or during environmental aging processes. The mechanisms of MoS₂ nanosheet toxicity to soil invertebrates and the role of surface defects in that toxicity have not been fully elucidated. We integrated traditional toxicity end points, targeted energy metabolomics, and transcriptomics to compare the mechanistic differences in the toxicity of defect-free and defect-rich MoS₂ nanosheets (DF-MoS₂ and DR-MoS₂) to Eisenia fetida using a coelomocyte-based in vivo assessment model. After organism-level exposure to DF-MoS₂ for 96 h at 10 and 100 mg Mo/L, cellular reactive oxygen species (ROS) levels were elevated by 25.6-96.6% and the activity of mitochondrial respiratory electron transport chain (Mito-RETC) complex III was inhibited by 9.7-19.4%. The tricarboxylic acid cycling and glycolysis were also disrupted. DF-MoS₂ preferentially up-regulated subcellular component motility processes related to microtubules and caused mitochondrial fission. Unlike DF-MoS₂, DR-MoS₂ triggered an increased degree of mitochondrial fusion, as well as more severe oxidative stress. The activities of Mito-RETC complexes (I, III, IV, V) associated with oxidative phosphorylation were significantly inhibited by 22.8-68.6%. Meanwhile, apoptotic pathways were activated upon DR-MoS₂ exposure, which together with the depolarization of mitochondrial membrane potential, mediated significant apoptosis. In turn, genes related to cellular homeostasis and energy release were up-regulated to compensate for DR-MoS₂-induced energy deprivation. Our study indicates that MoS₂ nanosheets have nanospecific effects on E. fetida and also that the role of surface defects from synthesis or that accumulate from environmental impacts needs to be fully considered when evaluating the toxicity of these 2D materials.

Environmentally sustainable implementations of two-dimensional nanomaterials

Rapid advancement in nanotechnology has led to the development of a myriad of useful nanomaterials that have novel characteristics resulting from their small size and engineered properties. In particular, two-dimensional (2D) materials have become a major focus in material science and chemistry research worldwide with substantial efforts centered on their synthesis, property characterization, and technological, and environmental applications. Environmental applications of these nanomaterials include but are not limited to adsorbents for wastewater and drinking water treatment, membranes for desalination, and coating materials for filtration. However, it is also important to address the environmental interactions and implications of these nanomaterials in order to develop strategies that minimize their environmental and public health risks. Towards this end, this review covers the most recent literature on the environmental implementations of emerging 2D nanomaterials, thereby providing insights into the future of this fast-evolving field including strategies for ensuring sustainable development of 2D nanomaterials.

Multifunctional Graphene Oxide Nanodelivery Platform for Breast Cancer Treatment

Background

Breast cancer (BC) has the highest global prevalence among all malignancies in women and the second highest prevalence in the overall population. Paclitaxel (PTX), a tricyclic diterpenoid, is effective against BC. However, its poor solubility in water and the allergenicity of its dissolution medium limited its clinical application.

Methods

In this work, we established a multifunctional graphene oxide (GO) tumor-targeting drug delivery system using nanosized graphene oxide (nGO) modified with D-tocopherol polyethylene glycol succinate (TPGS) and arginine-glycine-aspartic acid (RGD) for PTX loading.

Results

The obtained RGD-TPGS-nGO-PTX was 310.20±19.86 nm in size; the polydispersity index (PDI) and zeta potential were 0.21±0.020 and -23.42 mV, respectively. The mean drug loading capacity of RGD-TPGS-nGO-PTX was 48.78%. RGD-TPGS-nGO-PTX showed satisfactory biocompatibility and biosafety and had no significant toxic effects on zebrafish embryos. Importantly, it exerted excellent cytotoxicity against MDA-MB-231 cells, reversed multi-drug resistance (MDR) in MCF-7/ADR cells, and showed significant anti-tumor efficacy in tumor-bearing nude mice.

Conclusion

These findings strongly suggested that the multifunctional GO tumor-targeting drug delivery system RGD-TPGS-nGO-PTX could be used in clinical settings to improve PTX delivery, reverse MDR and increase the therapeutic efficacy of BC treatment.

Biodegradation of Graphene Oxide by Insects (Tenebrio molitor Larvae): Role of the Gut Microbiome and Enzymes

Biodegradation of graphene materials is critical for understanding their environmental process and fate. Thus, biodegradation and mineralization of graphene oxide (GO) by an insect (yellow mealworms, Tenebrio molitor larvae) were investigated. Twenty mealworms could eat up a piece of GO film (1.5 × 1.5 cm) in 15 days. The ingested GO film underwent degradation, and the residual GO sheets were observed in the frass. Raman imaging confirmed that the residual GO (I_D/I_G, 1.16) was more defective than the pristine GO film (I_D/I_G, 0.95). ¹⁴C analysis showed that GO sheets were partially mineralized into CO₂ (0.26%) and assimilated into biomass compositions (e.g., lipid and protein) (0.36%). Gut microbes and extracellular enzymes in yellow mealworms played crucial roles in GO degradation, and the predominant gut microbes for GO biodegradation were identified as Enterobacteriaceae bacteria (e.g., Escherichia-Shigella sp.). Two biodegradation products belonging to hydroxylated or carboxylated aromatic compounds were formed with the assistance of electrons and hydroxyl radicals in mealworm guts. These findings are useful for better understanding the environmental and biological fate of graphene materials.

Graphdiyne-Related Materials in Biomedical Applications and Their Potential in Peripheral Nerve Tissue Engineering

Graphdiyne (GDY) is a new member of the family of carbon-based nanomaterials with hybridized carbon atoms of sp and sp², including α, β, γ, and (6,6,12)-GDY, which differ in their percentage of acetylene bonds. The unique structure of GDY provides many attractive features, such as uniformly distributed pores, highly π-conjugated structure, high thermal stability, low toxicity, biodegradability, large specific surface area, tunable electrical conductivity, and remarkable thermal conductivity. Therefore, GDY is widely used in energy storage, catalysis, and energy fields, in addition to biomedical fields, such as biosensing, cancer therapy, drug delivery, radiation protection, and tissue engineering. In this review, we first discuss the synthesis of GDY with different shapes, including nanotubes, nanowires, nanowalls, and nanosheets. Second, we present the research progress in the biomedical field in recent years, along with the biodegradability and biocompatibility of GDY based on the existing literature. Subsequently, we present recent research results on the use of nanomaterials in peripheral nerve regeneration (PNR). Based on the wide application of nanomaterials in PNR and the remarkable properties of GDY, we predict the prospects and current challenges of GDY-based materials for PNR.

Immunotoxicity of Carbon-Based Nanomaterials, Starring Phagocytes

In the field of science, technology and medicine, carbon-based nanomaterials and nanoparticles (CNMs) are becoming attractive nanomaterials that are increasingly used. However, it is important to acknowledge the risk of nanotoxicity that comes with the widespread use of CNMs. CNMs can enter the body via inhalation, ingestion, intravenously or by any other route, spread through the bloodstream and penetrate tissues where (in both compartments) they interact with components of the immune system. Like invading pathogens, CNMs can be recognized by large numbers of receptors that are present on the surface of innate immune cells, notably monocytes and macrophages. Depending on the physicochemical properties of CNMs, i.e., shape, size, or adsorbed contamination, phagocytes try to engulf and process CNMs, which might induce pro/anti-inflammatory response or lead to modulation and disruption of basic immune activity. This review focuses on existing data on the immunotoxic potential of CNMs, particularly in professional phagocytes, as they play a central role in processing and eliminating foreign particles. The results of immunotoxic studies are also described in the context of the entry routes, impacts of contamination and means of possible elimination. Mechanisms of proinflammatory effect depending on endocytosis and intracellular distribution of CNMs are highlighted as well.

Hazard assessment of abraded thermoplastic composites reinforced with reduced graphene oxide

Graphene-related materials (GRMs) are subject to intensive investigations and considerable progress has been made in recent years in terms of safety assessment. However, limited information is available concerning the hazard potential of GRM-containing products such as graphene-reinforced composites. In the present study, we conducted a comprehensive investigation of the potential biological effects of particles released through an abrasion process from reduced graphene oxide (rGO)-reinforced composites of polyamide 6 (PA6), a widely used engineered thermoplastic polymer, in comparison to as-produced rGO. First, a panel of well-established in vitro models, representative of the immune system and possible target organs such as the lungs, the gut, and the skin, was applied. Limited responses to PA6-rGO exposure were found in the different in vitro models. Only as-produced rGO induced substantial adverse effects, in particular in macrophages. Since inhalation of airborne materials is a key occupational concern, we then sought to test whether the in vitro responses noted for these materials would translate into adverse effects in vivo. To this end, the response at 1, 7 and 28 days after a single pulmonary exposure was evaluated in mice. In agreement with the in vitro data, PA6-rGO induced a modest and transient pulmonary inflammation, resolved by day 28. In contrast, rGO induced a longer-lasting, albeit moderate inflammation that did not lead to tissue remodeling within 28 days. Taken together, the present study suggests a negligible impact on human health under acute exposure conditions of GRM fillers such as rGO when released from composites at doses expected at the workplace.

Biotransformation of graphene oxide within lung fluids could intensify its synergistic biotoxicity effect with cadmium by inhibiting cellular efflux of cadmium

Graphene oxide (GO) has been widely studied and applied in numerous industrial fields and biomedical fields for its excellent physical and chemical properties. Along with the production and applications of GO persist increasing, the environmental health and safety risk (EHS) of GO has been widely studied. However, previous studies almost focused on the biotoxicity of pristine GO under a relatively high exposure dose, without considering its transformation process within environmental and biological mediums. Meanwhile, its secondary toxicity or synergistic effects have not been taken seriously. Here, two different kinds of artificial lung fluids were adopted to incubate pristine GO to mimic the biotransformation process of GO in the lung fluids. And, we explored that biotransformation within the artificial lung fluids could significantly change the physicochemical properties of GO and could enhance its biotoxicity. To reveal the synergistic effects of GO and toxic metal ions, we uncovered that GO could enhance the intracellular content of metal ions by inhibiting the efflux function of ATP binding cassette (ABC) transporters which are distributed on the cellular membrane, and artificial lung fluids incubation of GO could enhance this synergistic effect. Finally, toxic metal ions induced a series of toxic reactions through oxidative stress response and promoted cell death. Moreover, consistent with the results of in vitro experiments, the lungs of mice exposed to GOs combined with Cd exhibited significant inflammation and oxidative stress compared with Cd treatment alone, and it was more remarkable within the mice which were treated with bio-transformed GOs. In summary, this study explored the impact and mechanism of biotransformation of GO in the lung fluids on the synergistic and secondary effects between GO and metal ions.

Dual-Driven Mechanically and Tribologically Adaptive Hydrogels Solely Constituted of Graphene Oxide and Water

Although mythologies and fictions have recorded living creatures fully composed of inorganics, it is however hard to turn inorganic constituents into lifelike materials in reality as they usually do not possess characteristics required for constructing a living organism. Here, we report to our knowledge the first biomimetic hydrogel in response to both pH and temperature variations that solely comprises graphene oxide and water. The hydrogel is capable of abruptly and reversibly switching its mechanical and tribological properties by more than 10-fold and 5-fold magnitudes, respectively, as a result of pH- and/or thermal-induced topological reconfiguration of its internal microstructure and ordering. Such behavior closely mimics some natural living organisms such as muscles and sea cucumbers. The hydrogel also shows a low coefficient of friction at pH 2 and room temperature, indicating it a potent smart lubricant free of any flammable and toxic organic base oils and additives.

MicroRNA-29b/graphene oxide–polyethyleneglycol–polyethylenimine complex incorporated within chitosan hydrogel promotes osteogenesis

MicroRNAs (miRNAs) play a pivotal role in regulating a number of physiologic and pathologic processes including bone marrow mesenchymal stem cell (BMSC) osteogenic differentiation, making them a candidate used to promote osteogenesis. However, due to intrinsic structure and characteristics, “naked” miRNAs are unstable in serum and could not pass across the cellular membrane. Nano delivery systems seem to be a solution to these issues. Recently, graphene oxide (GO)-based nanomaterials are considered to be promising for gene delivery due to their unique physiochemical characteristics such as high surface area, biocompatibility, and easy modification. In this work, a GO-based nanocomplex functionalized by polyethyleneglycol (PEG) and polyethylenimine (PEI) was prepared for loading and delivering miR-29b, which participates in multiple steps of bone formation. The nanocomplex revealed good biocompatibility, miRNA loading capacity, and transfection efficiency. The miR-29b/GO-PEG-PEI nanocomplex was capsulated into chitosan (CS) hydrogel for osteogenesis. In vitro and in vivo evaluation indicated that miR-29b/GO-PEG-PEI@CS composite hydrogel was able to promote BMSC osteogenic differentiation and bone regeneration. All these results indicate that PEG/PEI functionalized GO could serve as a promising candidate for miRNA cellular delivery, and the miR-29b/GO-PEG-PEI@CS hydrogel has the potential for repairing bone defects in vivo.

Physical Adsorption of Graphene Oxide onto Polymer Latexes and Characterization of the Resulting Nanocomposite Particles

Polymer/graphene oxide (GO) nanocomposite particles were prepared via heteroflocculation between 140-220 nm cationic latex nanoparticles and anionic GO nanosheets in either acidic or basic conditions. It is demonstrated that nanocomposite particles can be formed using either poly(2-vinylpyridine)-b-poly(benzyl methacrylate) (P2VP-PBzMA) block copolymer nanoparticles prepared by reversible-addition chain-transfer (RAFT)-mediated polymerization-induced self-assembly (PISA), or poly(ethylene glycol)methacrylate (PEGMA)-stabilized P2VP latexes prepared by traditional emulsion polymerization. These two latexes are different morphologically as the P2VP-PBzMA block copolymer latexes have P2VP steric stabilizer chains in their corona, whereas the PEGMA-stabilized P2VP particles have a P2VP core and a nonionic steric stabilizer. Nevertheless, both the P2VP-PBzMA and PEGMA-stabilized P2VP latexes are cationic at low pH. Thus, the addition of GO to these latexes causes flocculation to occur immediately due to the opposite charges between the anionic GO nanosheets and cationic latexes. Control heteroflocculation experiments were conducted using anionic sterically stabilized poly(potassium 3-sulfopropyl methacrylate)-b-poly(benzyl methacrylate) (PKSPMA-PBzMA) and nonionic poly(benzyl methacrylate) (PBzMA) nanoparticles to demonstrate that polymer/GO nanocomposite particles were not formed. The degree of flocculation and the strength of electrostatic interaction between the cationic polymer latexes and GO were assessed using disc centrifuge photosedimentometry (DCP), transmission electron microscopy (TEM), and UV-visible spectrophotometry. These studies suggest that the optimal conditions for the formation of polymer/GO nanocomposite particles were GO contents between 10% and 20% w/w relative to latex, with the latexes containing P2VP in their corona having a stronger electrostatic attraction to the GO sheets.

Understanding the bidirectional interactions between two-dimensional materials, microorganisms, and the immune system

Two-dimensional (2D) materials such as the graphene-based materials, transition metal dichalcogenides, transition metal carbides and nitrides (MXenes), black phosphorus, hexagonal boron nitride, and others have attracted considerable attention due to their unique physicochemical properties. This is true not least in the field of medicine. Understanding the interactions between 2D materials and the immune system is therefore of paramount importance. Furthermore, emerging evidence suggests that 2D materials may interact with microorganisms - pathogens as well as commensal bacteria that dwell in and on our body. We discuss the interplay between 2D materials, the immune system, and the microbial world in order to bring a systems perspective to bear on the biological interactions of 2D materials. The use of 2D materials as vectors for drug delivery and as immune adjuvants in tumor vaccines, and 2D materials to counteract inflammation and promote tissue regeneration, are explored. The bio-corona formation on and biodegradation of 2D materials, and the reciprocal interactions between 2D materials and microorganisms, are also highlighted. Finally, we consider the future challenges pertaining to the biomedical applications of various classes of 2D materials.

Combined Photothermal and Photodynamic Therapy for Cancer Treatment Using a Multifunctional Graphene Oxide

Graphene oxide (GO) is one of the most studied nanomaterials in many fields, including the biomedical field. Most of the nanomaterials developed for drug delivery and phototherapies are based on noncovalent approaches that lead to an unspecific release of physisorbed molecules in complex biological environments. Therefore, preparing covalently functionalized GO using straightforward and versatile methods is highly valuable. Phototherapies, including photothermal therapy (PTT) and photodynamic therapy (PDT), have shown great potential as effective therapeutic approaches against cancer. To overcome the limits of a single method, the combination of PTT and PDT can lead to a combined effect with a higher therapeutic efficiency. In this work, we prepare a folic acid (FA) and chlorin e6 (Ce6) double-functionalized GO for combined targeted PTT/PDT. This conjugate can penetrate rapidly into cancer cells and macrophages. A combined effect of PTT and PDT is observed, leading to a higher killing efficiency toward different types of cells involved in cancer and other diseases. Our work provides a simple protocol to prepare multifunctional platforms for the treatment of various diseases.

How to evaluate the potential toxicity of therapeutic carbon nanomaterials? A comprehensive study of carbonized nanogels with multiple animal toxicity test models

Carbon-based nanomaterials have great potential in medical applications, especially in the treatment of infectious diseases and even tumors. However, to safely execute the application of carbon nanomaterials in human treatments, conducting safety assessments and establishing suitable evaluation criteria are necessary. In this study, lysine-carbonized nanogels (Lys-CNGs) that display antibacterial and antiviral abilities were employed in a comprehensive evaluation of their toxicity profiles through assessments in different animal models and growth stages. It was observed that zebrafish at the embryo and eleutheroembryo stages experienced significant toxic effects at a concentration of 15-fold the recommended dosage (0.5 ppm), whereas adult zebrafish following long-term consumption of fodder containing Lys-CNGs presented no adverse effects. Further microbiota analysis indicated that Lys-CNGs did not cause significant changes in the composition of the intestinal bacteria. In contrast, in the toxicity assessments with mammalian animal models, the Lys-CNGs showed no adverse effects, such as weight loss, dermal irritation, and skin sensitization responses in rabbits and guinea pigs, even at a high dose of 2000 mg/kg body weight. Our study revealed that Lys-CNGs have different toxic effects on different growth stages of zebrafish. Researchers in this field should carefully consider the implications of these toxicity profiles during the development of therapeutic carbon-based nanomaterials and for comparison of studies.

Ultra-low binder content 3D printed calcium phosphate graphene scaffolds as resorbable, osteoinductive matrices that support bone formation in vivo

Bone regenerative engineering could replace autografts; however, no synthetic material fulfills all design criteria. Nanocarbons incorporated into three-dimensional printed (3DP) matrices can improve properties, but incorporation is constrained to low wt%. Further, unmodified nanocarbons have limited osteogenic potential. Functionalization to calcium phosphate graphene (CaPG) imparts osteoinductivity and osteoconductivity, but loading into matrices remained limited. This work presents ultra-high content (90%), 3DP-CaPG matrices. 3DP-CaPG matrices are highly porous (95%), moderately stiff (3 MPa), and mechanically robust. In vitro, they are cytocompatible and induce osteogenic differentiation of human mesenchymal stem cells (hMSCs), indicated by alkaline phosphatase, mineralization, and COL1α1 expression. In vivo, bone regeneration was studied using a transgenic fluorescent-reporter mouse non-union calvarial defect model. 3DP-CaPG stimulates cellular ingrowth, retains donor cells, and induces osteogenic differentiation. Histology shows TRAP staining around struts, suggesting potential osteoclast activity. Apparent resorption of 3DP-CaPG was observed and presented no toxicity. 3DP-CaPG represents an advancement towards a synthetic bone regeneration matrix.

Biomass-derived porous carbon with high drug adsorption capacity undergoes enzymatic and chemical degradation

Degradability is a key safety issue when choosing materials for biomedical applications and environmental protection. This factor greatly limits the application of porous carbon in these areas due to the inert and stable nature of carbon network. In this work, this conflict could be well-resolved by rational designing a mesoporous carbon (MC) with biomass as a carbon source. The retained oxygen-containing species simultaneously increase drug adsorption capacity and the degradability of MC. The maximum adsorption quantity for doxorubicin over MC can reach 395.3 mg/g, about 3-fold over carbon nanotubes. The detailed analysis reveals that the degradation of MC occurs via a radical mediated oxidation process. The high electron density feature of MC facilitates the electrophilic addition reaction in the presence of HO. During this process, the carbon network is gradually degraded into fragments, carbon nanodots and ultimately to CO₂. This work opens up a new way to fabricate degradable porous materials and provides a promising material for the practical application in biomedical and environmental field.

Encountering and Wrestling: Neutrophils Recognize and Defensively Degrade Graphene Oxide

The boosting exploitation of graphene oxide (GO) increases exposure risk to human beings. However, as primary defender in the first immune line, neutrophils' mechanism of defensive behavior toward GO remains unclear. Herein, we discovered that neutrophils recognize and defensively degrade GO in a lateral dimension dependent manner. The micrometer-sized GO (mGO) induces NETosis by releasing neutrophil extracellular traps (NETs), while nanometer-sized GO (nGO) elicits neutrophil degranulation. The two neutrophils' defensive behaviors are accompanied with generation of reactive oxygen species and activation of p-ERK and p-Akt kinases. However, mGO-induced NETosis is NADPH oxidase (NOX)-independent while nGO-triggered degranulation is NOX-dependent. Furthermore, myeloperoxidase (MPO) is determinant mediator despite distinct neutrophil phenotypes. Neutrophils release NETs comprising of MPO upon activated with mGO, while MPO is secreted via nGO-induced degranulation. Moreover, the binding energy between MPO and GO is calculated to be 69.8728 kJ mol^-1 , indicating that electrostatic interactions mainly cause the spontaneous binding process. Meanwhile, the central enzymatic biodegradation occurs at oxygenic active sites and defects on GO. Mass spectrometry analysis deciphers the degradation products are biocompatible molecules like flavonoids and polyphenols. This study provides fundamental evidence and practical guidance for nanotechnology based on GO, including vaccine adjuvant, implantable devices, and energy storage.

Graphene Oxide and Biomolecules for the Production of Functional 3D Graphene-Based Materials

Graphene and its derivatives have been widely employed in the manufacturing of novel composite nanomaterials which find applications across the fields of physics, chemistry, engineering and medicine. There are many techniques and strategies employed for the production, functionalization, and assembly of graphene with other organic and inorganic components. These are characterized by advantages and disadvantages related to the nature of the specific components involved. Among many, biomolecules and biopolymers have been extensively studied and employed during the last decade as building blocks, leading to the realization of graphene-based biomaterials owning unique properties and functionalities. In particular, biomolecules like nucleic acids, proteins and enzymes, as well as viruses, are of particular interest due to their natural ability to self-assemble via non-covalent interactions forming extremely complex and dynamic functional structures. The capability of proteins and nucleic acids to bind specific targets with very high selectivity or the ability of enzymes to catalyse specific reactions, make these biomolecules the perfect candidates to be combined with graphenes, and in particular graphene oxide, to create novel 3D nanostructured functional biomaterials. Furthermore, besides the ease of interaction between graphene oxide and biomolecules, the latter can be produced in bulk, favouring the scalability of the resulting nanostructured composite materials. Moreover, due to the presence of biological components, graphene oxide-based biomaterials are more environmentally friendly and can be manufactured more sustainably compared to other graphene-based materials assembled with synthetic and inorganic components. This review aims to provide an overview of the state of the art of 3D graphene-based materials assembled using graphene oxide and biomolecules, for the fabrication of novel functional and scalable materials and devices.

Graphene and graphene-based materials in axonal repair of spinal cord injury

Graphene and graphene-based materials have the ability to induce stem cells to differentiate into neurons, which is necessary to overcome the current problems faced in the clinical treatment of spinal cord injury. This review summarizes the advantages of graphene and graphene-based materials (in particular, composite materials) in axonal repair after spinal cord injury. These materials have good histocompatibility, and mechanical and adsorption properties that can be targeted to improve the environment of axonal regeneration. They also have good conductivity, which allows them to make full use of electrical nerve signal stimulation in spinal cord tissue to promote axonal regeneration. Furthermore, they can be used as carriers of seed cells, trophic factors, and drugs in nerve tissue engineering scaffolds to provide a basis for constructing a local microenvironment after spinal cord injury. However, to achieve clinical adoption of graphene and graphene-based materials for the repair of spinal cord injury, further research is needed to reduce their toxicity.

Fabrication of Polymer/Graphene Biocomposites for Tissue Engineering

Graphene-based materials (GBM) are considered one of the 21st century’s most promising materials, as they are incredibly light, strong, thin and have remarkable electrical and thermal properties. As a result, over the past decade, their combination with a diverse range of synthetic polymers has been explored in tissue engineering (TE) and regenerative medicine (RM). In addition, a wide range of methods for fabricating polymer/GBM scaffolds have been reported. This review provides an overview of the most recent advances in polymer/GBM composite development and fabrication, focusing on methods such as electrospinning and additive manufacturing (AM). As a future outlook, this work stresses the need for more in vivo studies to validate polymer/GBM composite scaffolds for TE applications, and gives insight on their fabrication by state-of-the-art processing technologies.

Understanding Nanomaterial-Liver Interactions to Facilitate the Development of Safer Nanoapplications

Nanomaterials (NMs) are widely used in commercial and medical products, such as cosmetics, vaccines, and drug carriers. Exposure to NMs via various routes such as dermal, inhalation, and ingestion has been shown to gain access to the systemic circulation, resulting in the accumulation of NMs in the liver. The unique organ structures and blood flow features facilitate the liver sequestration of NMs, which may cause adverse effects in the liver. Currently, most in vivo studies are focused on NMs accumulation at the organ level and evaluation of the gross changes in liver structure and functions, however, cell-type-specific uptake and responses, as well as the molecular mechanisms at cellular levels leading to effects at organ levels are lagging. Herein, the authors systematically review diverse interactions of NMs with the liver, specifically on major liver cell types including Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), hepatic stellate cells (HSCs), and hepatocytes as well as the detailed molecular mechanisms involved. In addition, the knowledge gained on nano-liver interactions that can facilitate the development of safer nanoproducts and nanomedicine is also reviewed.

Multifunctional carbon nanomaterials for diagnostic applications in infectious diseases and tumors

Infectious diseases (such as Corona Virus Disease 2019) and tumors pose a tremendous challenge to global public health. Early diagnosis of infectious diseases and tumors can lead to effective control and early intervention of the patient's condition. Over the past few decades, carbon nanomaterials (CNs) have attracted widespread attention in different scientific disciplines. In the field of biomedicine, carbon nanotubes, graphene, carbon quantum dots and fullerenes have the ability of improving the accuracy of the diagnosis by the improvement of the diagnostic approaches. Therefore, this review highlights their applications in the diagnosis of infectious diseases and tumors over the past five years. Recent advances in the field of biosensing, bioimaging, and nucleic acid amplification by such CNs are introduced and discussed, emphasizing the importance of their unique properties in infectious disease and tumor diagnosis and the challenges and opportunities that exist for future clinical applications. Although the application of CNs in the diagnosis of several diseases is still at a beginning stage, biosensors, bioimaging technologies and nucleic acid amplification technologies built on CNs represent a new generation of promising diagnostic tools that further support their potential application in infectious disease and tumor diagnosis.

•

Carbon nanomaterials (CNs) are systematically introduced in this review.

•

This review studies the application of CNs in infectious diseases and tumors diagnosis.

•

CNs act as potent nanostructures for biosensing, bioimaging, & nucleic acid amplification.

•

New CN-based detection methods were introduced to detect SARS-CoV-2.

•

The challenges and prospects of CN-based diagnostic assays are also discussed.

Development of Graphene-Based Materials in Bone Tissue Engineaering

Bone regeneration-related graphene-based materials (bGBMs) are increasingly attracting attention in tissue engineering due to their special physical and chemical properties. The purpose of this review is to quantitatively analyze mass academic literature in the field of bGBMs through scientometrics software CiteSpace, to demonstrate the rules and trends of bGBMs, thus to analyze and summarize the mechanisms behind the rules, and to provide clues for future research. First, the research status, hotspots, and frontiers of bGBMs are analyzed in an intuitively and vividly visualized way. Next, the extracted important subjects such as fabrication techniques, cytotoxicity, biodegradability, and osteoinductivity of bGBMs are presented, and the different mechanisms, in turn, are also discussed. Finally, photothermal therapy, which is considered an emerging area of application of bGBMs, is also presented. Based on this approach, this work finds that different studies report differing opinions on the biological properties of bGBMS due to the lack of consistency of GBMs preparation. Therefore, it is necessary to establish more standards in fabrication, characterization, and testing for bGBMs to further promote scientific progress and clinical translation.

Two-dimensional biomaterials: material science, biological effect and biomedical engineering applications

To date, nanotechnology has increasingly been identified as a promising and efficient means to address a number of challenges associated with public health. In the past decade, two-dimensional (2D) biomaterials, as a unique nanoplatform with planar topology, have attracted explosive interest in various fields such as biomedicine due to their unique morphology, physicochemical properties and biological effect. Motivated by the progress of graphene in biomedicine, dozens of types of ultrathin 2D biomaterials have found versatile bio-applications, including biosensing, biomedical imaging, delivery of therapeutic agents, cancer theranostics, tissue engineering, as well as others. The effective utilization of 2D biomaterials stems from the in-depth knowledge of structure-property-bioactivity-biosafety-application-performance relationships. A comprehensive summary of 2D biomaterials for biomedicine is still lacking. In this comprehensive review, we aim to concentrate on the state-of-the-art 2D biomaterials with a particular focus on their versatile biomedical applications. In particular, we discuss the design, fabrication and functionalization of 2D biomaterials used for diverse biomedical applications based on the up-to-date progress. Furthermore, the interactions between 2D biomaterials and biological systems on the spatial-temporal scale are highlighted, which will deepen the understanding of the underlying action mechanism of 2D biomaterials aiding their design with improved functionalities. Finally, taking the bench-to-bedside as a focus, we conclude this review by proposing the current crucial issues/challenges and presenting the future development directions to advance the clinical translation of these emerging 2D biomaterials.

Biodegradation of graphdiyne oxide in classically activated (M1) macrophages modulates cytokine production

Graphdiyne oxide (GDYO) is a carbon-based nanomaterial possessing sp² and sp-hybridized carbon atoms with many promising applications. However, its biocompatibility and potential biodegradability remain poorly understood. Using human primary monocyte-derived macrophages as a model we show here that GDYO elicited little or no cytotoxicity toward classically activated (M1) and alternatively activated (M2) macrophages. Moreover, GDYO reprogrammed M2 macrophages towards M1 macrophages, as evidenced by the elevation of specific cell surface markers and cytokines and the induction of NOS2 expression. We could also show inducible nitric oxide synthase (iNOS)-dependent biodegradation of GDYO in M1 macrophages, and this was corroborated in an acellular system using the peroxynitrite donor, SIN-1. Furthermore, GDYO elicited the production of pro-inflammatory cytokines in a biodegradation-dependent manner. Our findings shed new light on the reciprocal interactions between GDYO and human macrophages. This is relevant for biomedical applications of GDYO such as the re-education of tumor-associated macrophages or TAMs.

Roles of Graphene Oxide in Heterogeneous Photocatalysis

Graphene oxide (GO) has been widely utilized as the precursor of graphene (GR) to fabricate GR-based hybrid photocatalysts for solar-to-chemical energy conversion. However, until now, the properties and roles that GO played in heterogeneous photocatalysis have remained relatively elusive. In this Review, we start with a brief discussion of synthesis and structure of GO. Then, the photocatalysis-related properties of GO, including electrical conductivity, surface chemistry, dispersibility, and semiconductor properties, are concisely summarized. In particular, we have highlighted the fundamental multifaceted roles of GO in heterogeneous photocatalysis, which contain the precursor of GR, cross-linked framework for constructing aerogel photocatalyst, macromolecular surfactant, two-dimensional growth template, and photocatalyst by itself. Furthermore, the future prospects and remaining challenges on developing effective GO-derived hybrid photocatalysts are presented, which is expected to inspire further research into this promising research domain.

Stimulation of Innate and Adaptive Immune Cells with Graphene Oxide and Reduced Graphene Oxide Affect Cancer Progression

Sole nanomaterials or nanomaterials bound to specific biomolecules have been proposed to regulate the immune system. These materials have now emerged as new tools for eliciting immune-based therapies to treat various cancers. Graphene, graphene oxide (GO) and reduced GO (rGO) are the latest nanomaterials among other carbon nanotubes that have attracted wide interest among medical industry players due to their extraordinary properties, inert-state, non-toxic and stable dispersion in a various solvent. Currently, GO and rGO are utilized in various biomedical application including cancer immunotherapy. This review will highlight studies that have been carried out in elucidating the stimulation of GO and rGO on selected innate and adaptive immune cells and their effect on cancer progression to shed some insights for researchers in the development of various GO- and rGO-based immune therapies against various cancers.

Does black phosphorus hold potential to overcome graphene oxide? A comparative review of their promising application for cancer therapy

Although graphene oxide (GO) is leading the way in the biomedical field of 2D materials, nanosized black phosphorus (NBP) has recently come to attention for use in this challenging field. A direct comparison between these two materials, in this context, has never been described. Therefore, in this mini-review, we will critically compare the applications of NBP and GO in cancer therapy. Material functionalisation, biodegradation by design, phototherapy and immunotherapy will be summarised. This work aims to inspire researchers in designing the next generation of safe NBP platforms for cancer treatment, taking advantage of the vast experience gained with GO.

In Vivo Monitoring of Intracellular Metabolite in a Microalgal Cell Using an Aptamer/Graphene Oxide Nanosheet Complex

Real-time sensing and imaging of intracellular metabolites in living cells are crucial tools for the characterization of complex biological processes, including the dynamic fluctuation of metabolites. Therefore, additional efforts are required to develop in vivo detection strategies for the visualization and quantification of specific target metabolites, particularly in microalgae. In this study, we developed a strategy to monitor a specific microalgal metabolite in living cells using an aptamer/graphene oxide nanosheet (GOnS) complex. As a proof-of-concept, β-carotene, an antioxidant pigment that accumulates in most microalgal species, was chosen as a target metabolite. To achieve this, a β-carotene-specific aptamer was selected through graphene oxide-assisted systematic evolution of ligands by exponential enrichment (GO-SELEX) and characterized thereafter. The aptamer could sensitively sense the changes in the concentration of β-carotene (i.e., the target metabolite) and more specifically bind to β-carotene than to nontargets. The selected aptamer was labeled with a fluorophore (fluorescein; FAM) and allowed to form an aptamer/GOnS complex that protected the aptamer from nucleic cleavages. The aptamer/GOnS complex was delivered into the cells via electroporation, thus enabling the sensitive monitoring of β-carotene in the cell by quantifying the aptamer fluorescence intensity. The results suggest that our biocompatible strategy could be employed to visualize and semiquantify intracellular microalgae metabolites in vivo, which holds a great potential in diverse fields such as metabolite analysis and mutant screening.

Graphene Oxide Functionalized Double-Layered Patch with Anti-Adhesion Ability for Abdominal Wall Defects

Background

Effective repair of full-thickness abdominal wall defects requires a patch with sufficient mechanical strength and anti-adhesion characteristics to avoid the formation of hernias and intra-abdominal complications such as intestinal obstruction and fistula. However, patches made from polymers or bio-derived materials may not meet these requirements and lack the bionic characteristics of the abdominal wall.

Materials and Methods

In this study, we report a consecutive electrospun method for preparing a double-layer structured nanofiber membrane (GO-PCL/CS-PCL) using polycaprolactone (PCL), graphene oxide (GO) and chitosan (CS). To expand the bio-functions (angiogenesis/reducing reactive oxygen species) of the patch (GO-PCL/NAC-CS-PCL), N-acetylcysteine (NAC) was loaded for the repair of full-thickness abdominal wall defects (2×1.5cm) in rat model.

Results

The double-layered patch (GO-PCL/NAC-CS-PCL) showed excellent mechanical strength and biocompatibility. After 2 months, rats treated with the patch exhibited the desired repair effect with no hernia formation, less adhesion (adhesion score: 1.50±0.50, P<0.001) and more collagen deposition (percentage of collagen deposition: 34.94%±3.31%, P<0.001).

Conclusion

The double-layered nanomembranes presented in this study have good anti-hernia and anti-adhesion effects, as well as improve the microenvironment in vivo. It, therefore, holds good prospects for the repair of abdominal wall defects and provides a promising key as a postoperative anti-adhesion agent.

Graphene Oxide Topical Administration: Skin Permeability Studies

Nanostructured carriers have been widely used in pharmaceutical formulations for dermatological treatment. They offer targeted drug delivery, sustained release, improved biostability, and low toxicity, usually presenting advantages over conventional formulations. Due to its large surface area, small size and photothermal properties, graphene oxide (GO) has the potential to be used for such applications. Nanographene oxide (GOn) presented average sizes of 197.6 ± 11.8 nm, and a surface charge of -39.4 ± 1.8 mV, being stable in water for over 6 months. 55.5% of the mass of GOn dispersion (at a concentration of 1000 µg mL-1) permeated the skin after 6 h of exposure. GOn dispersions have been shown to absorb near-infrared radiation, reaching temperatures up to 45.7 °C, within mild the photothermal therapy temperature range. Furthermore, GOn in amounts superior to those which could permeate the skin were shown not to affect human skin fibroblasts (HFF-1) morphology or viability, after 24 h of incubation. Due to its large size, no skin permeation was observed for graphite particles in aqueous dispersions stabilized with Pluronic P-123 (Gt-P-123). Altogether, for the first time, Gon's potential as a topic administration agent and for delivery of photothermal therapy has been demonstrated.

Carbon-Based Nanomaterials: Promising Antiviral Agents to Combat COVID-19 in the Microbial-Resistant Era

Therapeutic options for the highly pathogenic human severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing the current pandemic coronavirus disease (COVID-19) are urgently needed. COVID-19 is associated with viral pneumonia and acute respiratory distress syndrome causing significant morbidity and mortality. The proposed treatments for COVID-19 have shown little or no effect in the clinic so far. Additionally, bacterial and fungal pathogens contribute to the SARS-CoV-2-mediated pneumonia disease complex. The antibiotic resistance in pneumonia treatment is increasing at an alarming rate. Therefore, carbon-based nanomaterials (CBNs), such as fullerene, carbon dots, graphene, and their derivatives constitute a promising alternative due to their wide-spectrum antimicrobial activity, biocompatibility, biodegradability, and capacity to induce tissue regeneration. Furthermore, the antimicrobial mode of action is mainly physical (e.g., membrane distortion), characterized by a low risk of antimicrobial resistance. In this Review, we evaluated the literature on the antiviral activity and broad-spectrum antimicrobial properties of CBNs. CBNs had antiviral activity against 13 enveloped positive-sense single-stranded RNA viruses, including SARS-CoV-2. CBNs with low or no toxicity to humans are promising therapeutics against the COVID-19 pneumonia complex with other viruses, bacteria, and fungi, including those that are multidrug-resistant.

Intranasal vaccination with influenza HA/GO-PEI nanoparticles provides immune protection against homo- and heterologous strains

Intranasal (i.n.) immunization is a promising vaccination route for infectious respiratory diseases such as influenza. Recombinant protein vaccines can overcome the safety concerns and long production phase of virus-based influenza vaccines. However, soluble protein vaccines are poorly immunogenic if administered by an i.n. route. Here, we report that polyethyleneimine-functionalized graphene oxide nanoparticles (GP nanoparticles) showed high antigen-loading capacities and superior immunoenhancing properties. Via a facile electrostatic adsorption approach, influenza hemagglutinin (HA) was incorporated into GP nanoparticles and maintained structural integrity and antigenicity. The resulting GP nanoparticles enhanced antigen internalization and promoted inflammatory cytokine production and JAWS II dendritic cell maturation. Compared with soluble HA, GP nanoparticle formulations induced significantly enhanced and cross-reactive immune responses at both systemic sites and mucosal surfaces in mice after i.n. immunization. In the absence of any additional adjuvant, the GP nanoparticle significantly boosted antigen-specific humoral and cellular immune responses, comparable to the acknowledged potent mucosal immunomodulator CpG. The robust immune responses conferred immune protection against challenges by homologous and heterologous viruses. Additionally, the solid self-adjuvant effect of GP nanoparticles may mask the role of CpG when coincorporated. In the absence of currently approved mucosal adjuvants, GP nanoparticles can be developed into potent i.n. influenza vaccines, providing broad protection. With versatility and flexibility, the GP nanoplatform can be easily adapted for constructing mucosal vaccines for different respiratory pathogens.

Toxicity and photosynthetic inhibition of metal-organic framework MOF-199 to pea seedlings

Metal-organic framework (MOF) materials are star materials with unique structures and properties. To ensure safe production and applications, the toxicity and environmental hazards of MOF materials should be thoroughly investigated. However, the environmental impact of MOF materials on plants is completely unknown. Herein, we reported the toxicity and photosynthetic inhibitory properties of MOF-199 to pea plants (Pisum sativum L.). MOF-199 was synthesized by hydrothermal method. MOF-199 was copper containing double-pyramid of high surface area (668 m2/g). MOF-199 accelerated the germination of pea seeds, but the total germination rates were unchanged. MOF-199 inhibited the seedling growth at high concentrations. The net photosynthetic rate increased, while the total photosynthesis capability decreased. Damage to the acceptor side of photosystem II was evidenced by chlorophyll fluorescence. Mechanistically, MOF-199 released Cu2+ in the nutrient solution, led to Cu2+ accumulations in seedlings, and promoted oxidative stress. In addition, the photosynthetic inhibitions of MOF-199 were stronger than equivalent concentrations of Cu(NO3)2, implying that MOF-199 particles also contributed to the environmental hazards. Our results highlighted the potential threat of MOF materials to plant growth and photosynthesis.

The Blanket Effect: How Turning the World Upside Down Reveals the Nature of Graphene Oxide Cytocompatibility

Extensive cytocompatibility testing of 2D nanocarbon materials including graphene oxide (GO) has been performed, but results remain contradictory. Literature has yet to account for settling-although sedimentation is visible to the eye and physics suggests that even individual graphenic flakes will settle. To investigate settling, a series of functional graphenic materials (FGMs) with differing oxidation levels, functionalities, and physical dimensions are synthesized. Though zeta potential indicates colloidal stability, significant gravitational settling of the FGMs is theoretically and experimentally demonstrated. By creating a setup to culture cells in traditional and inverted orientations in the same well, a "blanket effect" is demonstrated in which FGMs settle out of solution and cover cells at the bottom of the well, ultimately reducing viability. Inverted cells protected from the blanket effect are unaffected. Therefore, these results demonstrate that settling is a crucial factor that must be considered for FGM cytocompatibility experiments.