The impact of graphene oxide sheet lateral dimensions on their pharmacokinetic and tissue distribution profiles in mice

Safety Assessment of Graphene-Based Materials

Graphene is the first 2D atomic crystal, and its isolation heralded a new era in materials science with the emergence of several other atomically thin materials displaying multifunctional properties. The safety assessment of new materials is often something of an afterthought, but in the case of graphene, the initial isolation and characterization of the material was soon followed by the assessment of its potential impact on living systems. The Graphene Flagship project addressed the health and environmental aspects of graphene and other 2D materials, providing an instructive lesson in interdisciplinarity - from materials science to biology. Here, the outcomes of the toxicological and ecotoxicological studies performed on graphene and its derivatives, and the key lessons learned from this decade-long journey, are highlighted.

Interplay between the oxidation process and cytotoxic effects of antimonene nanomaterials

Pnictogen nanomaterials have recently attracted researchers' attention owing to their promising properties in the field of electronic, energy storage, and nanomedicine applications. Moreover, especially in the case of heavy pnictogens, their chemistry allows for nanomaterial synthesis using both top-down and bottom-up approaches, yielding materials with remarkable differences in terms of morphology, size, yield, and properties. In this study, we carried out a comprehensive structural and spectroscopic characterization of antimony-based nanomaterials (Sb-nanomaterials) obtained by applying different production methodologies (bottom-up and top-down routes) and investigating the influence of the synthesis on their oxidation state and stability in a biological environment. Indeed, in situ XANES/EXAFS studies of Sb-nanomaterials incubated in cell culture media were carried out, unveiling a different oxidation behavior. Furthermore, we investigated the cytotoxic effects of Sb-nanomaterials on six different cell lines: two non-cancerous (FSK and HEK293) and four cancerous (HeLa, SKBR3, THP-1, and A549). The results reveal that hexagonal antimonene (Sb-H) synthesized using a colloidal approach oxidizes the most and faster in cell culture media compared to liquid phase exfoliated (LPE) antimonene, suffering acute degradation and anticipating well-differentiated toxicity from its peers. In addition, the study highlights the importance of the synthetic route for the Sb-nanomaterials as it was observed to influence the chemical evolution of Sb-H into toxic Sb oxide species, playing a critical role in its ability to rapidly eliminate tumor cells. These findings provide insights into the mechanisms underlying the dark cytotoxicity of Sb-H and other related Sb-nanomaterials, underlining the importance of developing therapies based on controlled and on-demand nanomaterial oxidation.

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.

Pristine/folate-functionalized graphene oxide as two intrinsically radioiodinated nano-theranostics: self/dual in vivo targeting comparative study

Background

Nanomedicine offers great potentials for theranostic studies via providing higher efficacy and safety levels. This work aimed to develop and evaluate a new nanoplatform as a tumor theranostic probe.

Results

Carboxyl-functionalized graphene oxide nanosheets (FGO) was well synthesized from graphite powder and then conjugated with folic acid to act as a targeted nano-probe. Full characterization and in vitro cytotoxicity evaluation were conducted; besides, in vivo bio-evaluation was attained via intrinsic radioiodination approach in both normal and tumor-bearing Albino mice. The results indicated that FGO as well as conjugated graphene oxide nanosheets (CGO) are comparatively non-toxic to normal cells even at higher concentrations. Pharmacokinetics of FGO and CGO showed intensive and selective uptake in the tumor sites where CGO showed high T/NT of 7.27 that was 4 folds of FGO at 1 h post injection. Additionally, radioiodinated-CGO (ICGO) had declared a superior prominence over the previously published tumor targeted GO radiotracers regarding the physicochemical properties pertaining ability and tumor accumulation behavior.

Conclusions

In conclusion, ICGO can be used as a selective tumor targeting agent for cancer theranosis with aid of I-131 that has a maximum beta and gamma energies of 606.3 and 364.5 keV, respectively.

Molecular Imaging, Radiochemistry, and Environmental Pollutants

The worldwide proliferation of persistent environmental pollutants is accelerating at an alarming rate. Not surprisingly, many of these pollutants pose a risk to human health. In this review, we examine recent literature in which molecular imaging and radiochemistry have been harnessed to study environmental pollutants. Specifically, these techniques offer unique ways to interrogate the pharmacokinetic profiles and bioaccumulation patterns of pollutants at environmentally relevant concentrations, thereby helping to determine their potential health risks.

Applications of graphene-based nanomaterials in drug design: The good, the bad and the ugly

INTRODUCTION

Graphene-based materials (GBMs) have unique physicochemical properties that make them extremely attractive as platforms for the design of new drugs. Indeed, their bidimensional (2D) morphology, high surface area, mechanical and optical properties, associated to different possibilities for functionalization of their surface, provides opportunities for their use as nanomedicines for drug delivery and/or phototherapies.

AREAS COVERED

This opinion paper provides an overview of the current status of GBMs in drug design, with a focus on their therapeutic applications, potential environmental and health risks, and some controversial results. The authors discuss the chemical modifications of GBMs for the treatment of various diseases. The potential toxicity associated with some GBMs is also presented, along with a safe-by-design approach to minimize the risks. Finally, the authors address some issues associated to the use of GBMs in the biomedical field, such as contradictory antibacterial effects, fluorescence quenching and imprecise chemical functionalization.

EXPERT OPINION

GBMs are a promising and exciting area of research in drug delivery. It is however important that responsible and safe use of these materials is ensured to fully exploit their advantages and overcome their drawbacks.

Correlative radioimaging and mass spectrometry imaging: a powerful combination to study 14C-graphene oxide in vivo biodistribution

Research on graphene based nanomaterials has flourished in the last decade due their unique properties and emerging socio-economic impact. In the context of their potential exploitation for biomedical applications, there is a growing need for the development of more efficient imaging techniques to track the fate of these materials. Herein we propose the first correlative imaging approach based on the combination of radioimaging and mass spectrometry imaging for the detection of Graphene Oxide (GO) labelled with carbon-14 in mice. In this study, ¹⁴C-graphene oxide nanoribbons were produced from the oxidative opening of ¹⁴C-carbon nanotubes, and were then intensively sonicated to provide nano-size ¹⁴C-GO flakes. After Intravenous administration in mice, ¹⁴C-GO distribution was quantified by radioimaging performed on tissue slices. On the same slices, MS-imaging provided a highly resolved distribution map of the nanomaterial based on the detection of specific radical anionic carbon clusters ranging from C2˙^- to C9˙^- with a base peak at m/z 72 (¹²C) and 74 (¹⁴C) under negative laser desorption ionization mass spectrometry (LDI-MS) conditions. This proof of concept approach synergizes the strength of each technique and could be advantageous in the pre-clinical development of future Graphene-based biomedical applications.

Impact of graphene oxide lateral dimensions on the properties of methacrylated gelatin nanocomposite hydrogels

The size and shape of nanoparticles have a profound effect on the properties of nanocomposites. For instance, the lateral dimensions of graphene oxide (GO) platelets affect several properties, including their antibacterial and pharmacokinetic functions. However, the impact of lateral dimensions has been poorly studied in nanocomposites, and their effect on hydrogels is still unknown. The current study aims to determine the effect of GO lateral dimensions on the mechanical, rheological, thermal, and antibacterial properties of gelatin hydrogels. The hydrogels were fabricated via photopolymerization of methacrylated gelatin and GO derived from the oxidation of commercial graphene. The observations indicate that an increase in GO sheets improves the mechanical strength with an increase in compressive modulus and a low mechanical hysteresis (<10%). Furthermore, low mechanical energy is dissipated even after several deformation cycles. The nanocomposite hydrogels demonstrated bactericidal effects on two clinical strains with an extensively drug-resistant phenotype, primarily through contact. Additionally, an increment in lateral dimensions increased the bactericidal capacity of Gram-negative strains. Thus, the significant effect of the lateral dimensions of GO sheets on the properties of hydrogels is demonstrated.

Renal clearance of graphene oxide: glomerular filtration or tubular secretion and selective kidney injury association with its lateral dimension

BACKGROUND

Renal excretion is one of the major routes of nanomaterial elimination from the body. Many previous studies have found that graphene oxide nanosheets are excreted in bulk through the kidneys. However, how the lateral size affects GO disposition in the kidneys including glomerular filtration, active tubular secretion and tubular reabsorption is still unknown.

RESULTS

The thin, two-dimensional graphene oxide nanosheets (GOs) was observed to excrete in urine through the kidneys, but the lateral dimension of GOs affects their renal clearance pathway and renal injury. The s-GOs could be renal excreted via the glomerular filtration, while the l-GOs were predominately excreted via proximal tubular secretion at a much faster renal clearance rate than the s-GOs. For the tubular secretion of l-GOs, the mRNA level of basolateral organic anion transporters Oat1 and Oat2 in the kidney presented dose dependent increase, while no obvious alterations of the efflux transporters such as Mdr1 and Mrp4 mRNA expression levels were observed, suggesting the accumulation of l-GOs. During the GO renal elimination, mostly the high dose of 15 mg/kg s-GO and l-GO treatment showed obvious kidney injuries but at different renal compartment, i.e., the s-GOs induced obvious glomerular changes in podocytes, while the l-GOs induced more obvious tubular injuries including necrosis of renal tubular epithelial cells, loss of brush border, cast formation and tubular dilatation. The specifically tubular injury biomarkers KIM1 and NGAL were shown slight increase with mRNA levels in l-GO administrated mice.

CONCLUSIONS

This study shows that the lateral size of GOs affected their interactions with different renal compartments, renal excretion pathways and potential kidney injuries.

Understanding the Role of the Lateral Dimensional Property of Graphene Oxide on Its Interactions with Renal Cells

Renal excretion is expected to be the major route for the elimination of biomedically applied nanoparticles from the body. Hence, understanding the nanomedicine-kidney interaction is crucially required, but it is still far from being understood. Herein, we explored the lateral dimension- (~70 nm and ~300 nm), dose- (1, 5, and 15 mg/kg in vivo and 0.1~250 μg/mL in vitro), and time-dependent (48 h and 7 d in vivo) deposition and injury of PEGylated graphene oxide sheets (GOs) in the kidney after i.v. injection in mice. We specially investigated the cytotoxic effects on three typical kidney cell types with which GO renal excretion is related: human renal glomerular endothelial cells (HRGECs) and human podocytes, and human proximal tubular epithelial cells (HK-2). By using in vivo fluorescence imaging and in situ Raman imaging and spectroscopic analysis, we revealed that GOs could gradually be eliminated from the kidneys, where the glomeruli and renal tubules are their target deposition sites, but only the high dose of GO injection induced obvious renal histological and ultrastructural changes. We showed that the high-dose GO-induced cytotoxicity included a cell viability decrease and cellular apoptosis increase. GO uptake by renal cells triggered cellular membrane damage (intracellular LDH release) and increased levels of oxidative stress (ROS level elevation and a decrease in the balance of the GSH/GSSG ratio) accompanied by a mitochondrial membrane potential decrease and up-regulation of the expression of pro-inflammatory cytokines TNF-α and IL-18, resulting in cellular apoptosis. GO treatments activated Keap1/Nrf2 signaling; however, the antioxidant function of Nrf2 could be inhibited by apoptotic engagement. GO-induced cytotoxicity was demonstrated to be associated with oxidative stress and an inflammation reaction. Generally, the l-GOs presented more pronounced cytotoxicity and more severe cellular injury than s-GOs did, demonstrating lateral size-dependent toxicity to the renal cells. More importantly, GO-induced cytotoxicity was independent of renal cell type. The results suggest that the dosage of GOs in biomedical applications should be considered and that more attention should be paid to the ability of a high dose of GO to cause renal deposition and potential nephrotoxicity.

Diverse Pathways of Engineered Nanoparticle-Induced NLRP3 Inflammasome Activation

With the rapid development of engineered nanomaterials (ENMs) in biomedical applications, their biocompatibility and cytotoxicity need to be evaluated properly. Recently, it has been demonstrated that inflammasome activation may be a vital contributing factor for the development of biological responses induced by ENMs. Among the inflammasome family, NLRP3 inflammasome has received the most attention because it directly interacts with ENMs to cause the inflammatory effects. However, the pathways that link ENMs to NLRP3 inflammasome have not been thoroughly summarized. Thus, we reviewed recent findings on the role of major ENMs properties in modulating NLRP3 inflammasome activation, both in vitro and in vivo, to provide a better understanding of the underlying mechanisms. In addition, the interactions between ENMs and NLRP3 inflammasome activation are summarized, which may advance our understanding of safer designs of nanomaterials and ENM-induced adverse health effects.

Multifunctional graphene oxide nanoparticles for drug delivery in cancer

Recent advancements in nanotechnology have enabled us to develop sophisticated multifunctional nanoparticles or nanosystems for targeted diagnosis and treatment of several illnesses, including cancers. To effectively treat any solid tumor, the therapy should preferably target just the malignant cells/tissue with minor damage to normal cells/tissues. Graphene oxide (GO) nanoparticles have gained considerable interest owing to their two-dimensional planar structure, chemical/mechanical stability, excellent photosensitivity, superb conductivity, high surface area, and good biocompatibility in cancer therapy. Many compounds have been functionalized on the surface of GO to increase their biological applications and minimize cytotoxicity. The review presents an overview of the physicochemical characteristics, strategies for various modifications, toxicity and biocompatibility of graphene and graphene oxide, current trends in developing GO-based nano constructs as a drug delivery cargo and other biological applications, including chemo-photothermal therapy, chemo-photodynamic therapy, bioimaging, and theragnosis in cancer. Further, the review discusses the challenges and opportunities of GO, GO-based nanomaterials for the said applications. Overall, the review focuses on the therapeutic potential of strategically developed GO nanomedicines and comprehensively discusses their opportunities and challenges in cancer therapy.

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.