Cytotoxicity Of Graphene Quantum Dots Research Articles

Toxicity reduction of graphene quantum dots by photocatalysis

The widespread use and uncontrolled diffusion of nano-carbon materials are bringing threats to human health because the cytotoxicity of such materials increases over certain in-vivo concentrations. In the present study, the cytotoxicity of graphene quantum dots (GQDs) was reduced after photocatalysis with TiO2 and ultraviolet light. The FTIR and TEM analysis suggested that the hydrophilic functional groups of GQDs were removed, causing the aggregation of the nanoparticles and the reduction of water-diffused concentration. The treatment is valuable for the disposal of nano-carbon materials in the wastewater.

A review on the cytotoxicity of graphene quantum dots: from experiment to simulation.

Graphene quantum dots (GQDs) generate intrinsic fluorescence and improve the aqueous stability of graphene oxide (GO) while maintaining wide chemical adaptability and high adsorption capacity. Despite GO's remarkable advantages in bio-imaging, bio-sensing, and other biomedical applications, many experiments and simulations have focused on the biosafety of GQDs. Here, we review the findings on the biosafety of GQDs from experiments; then, we review the results from simulated interactions with biological membranes, DNA molecules, and proteins; finally, we examine the intersection between experiments and simulations. The biosafety results from simulations are explained in detail. Based on the literature and our experiments, we also discuss the trends toward GQDs with better biosafety.

Recent Advances in the Cancer Bioimaging with Graphene Quantum Dots

Fluorescent graphene quantum dots (GQDs) have attracted increasing interest in cancer bioimaging due to their stable photoluminescence (PL), high stability, low cytotoxicity, and good biocompatibility. In this review, we present the synthesis and chemical modification of GQDs firstly, and then introduce their unique physical, chemical, and biological properties like the absorption, PL, and cytotoxicity of GQDs. Finally and most importantly, the recent applications of GQDs in cancer bioimaging are demonstrated in detail, in which we focus on the biofunctionalization of GQDs for specific cancer cell imaging and real-time molecular imaging in live cells. We expect this work would provide valuable guides on the synthesis and modification of GQDs with adjustable properties for various biomedical applications in the future.

How functional groups influence the ROS generation and cytotoxicity of graphene quantum dots

Herein we selectively deactivate the ketonic carbonyl, carboxylic, or hydroxyl groups on GQDs and compare the ROS generation ability of different GQD derivatives. The results indicate that the ROS generation ability of GQDs is closely related to the ketonic carbonyl groups. Removal of the oxygen functional groups on GQDs can increase the photostability and lower the photoinduced cytotoxicity.

Theoretical Evaluation on Potential Cytotoxicity of Graphene Quantum Dots.

Owing to unique morphology, ultrasmall lateral sizes, and exceptional properties, graphene quantum dots (GQDs) hold great potential in many applications, especially in the field of electrochemical biosensors, bioimaging, drug delivery, et cetera. Its biosafety and potential cytotoxicity to human and animal cells has been a growing concern in recent years. In this work, the potential cytotoxicity of GQDs was evaluated by molecular dynamics simulations. Our simulation demonstrates that small size GQDs could easily permeate into the lipid membrane in a vertical way. It is relatively difficult to permeate into the lipid membrane for GQDs that are larger than GQD61 on the nanosecond time-scale. The thickness of the POPC membrane could even be affected by the small size of GQDs. Free energy calculations revealed that the free energy barrier of GQD permeation through the lipid membrane could greatly change with the change of GQD size. Under high GQD concentration, the GQD molecules could rapidly aggregate in water but disaggregate after entering into the membrane interior. Moreover, high concentrations of GQDs could induce changes in the structure properties and diffusion properties of the lipid bilayer, and it may affect the cell signal transduction. However, GQDs with relatively small size are not large enough to mechanically damage the lipid membrane. Our results suggest that the cytotoxicity of GQDs with small size is low and may be appropriate for biomedical application.

Mitigating the Cytotoxicity of Graphene Quantum Dots and Enhancing Their Applications in Bioimaging and Drug Delivery.

Despite the promising photophysical properties of fluorescent graphene quantum dots (GQDs), their cellular toxicity needs to be addressed before their full potential could be completely realized in biomedicine. A simple method for mitigating the toxicity of GQDs by embedding them in PEG matrix is reported here. The enhanced biocompatibility of polymer modified, P-GQDs, is attributed to reduced reactive oxygen species generation, as measured by an intracellular ROS assay. We also demonstrate the enhanced loading and efficient intracellular delivery of therapeutics by P-GQDs.

Cellular distribution and cytotoxicity of graphene quantum dots with different functional groups

Graphene quantum dots (GQDs) have been developed as promising optical probes for bioimaging due to their excellent photoluminescent properties. Additionally, the fluorescence spectrum and quantum yield of GQDs are highly dependent on the surface functional groups on the carbon sheets. However, the distribution and cytotoxicity of GQDs functionalized with different chemical groups have not been specifically investigated. Herein, the cytotoxicity of three kinds of GQDs with different modified groups (NH2, COOH, and CO-N (CH3)2, respectively) in human A549 lung carcinoma cells and human neural glioma C6 cells was investigated using thiazoyl blue colorimetric (MTT) assay and trypan blue assay. The cellular apoptosis or necrosis was then evaluated by flow cytometry analysis. It was demonstrated that the three modified GQDs showed good biocompatibility even when the concentration reached 200 μg/mL. The Raman spectra of cells treated with GQDs with different functional groups also showed no distinct changes, affording molecular level evidence for the biocompatibility of the three kinds of GQDs. The cellular distribution of the three modified GQDs was observed using a fluorescence microscope. The data revealed that GQDs randomly dispersed in the cytoplasm but not diffused into nucleus. Therefore, GQDs with different functional groups have low cytotoxicity and excellent biocompatibility regardless of chemical modification, offering good prospects for bioimaging and other biomedical applications.

Graphene: Insight into the Cellular Internalization and Cytotoxicity of Graphene Quantum Dots (Adv. Healthcare Mater. 12/2013)

On page 1613 Shouwu Guo and co-workers present how graphene quantum dots (GQDs) with unique morphology and ultrasmall lateral sizes are internalized primarily via caveolae-mediated endocytosis, and tend to accumulate in the endoplasmic reticulum and nucleus. The GQDs also exhibit lower cytotoxicity than that of the micrometer-sized graphene oxide, which prefers to stay in the cytoplasm. The subcellular distribution and low cytotoxicity of GQDs hold great promise in biomedical applications.

Insight into the Cellular Internalization and Cytotoxicity of Graphene Quantum Dots

Graphene quantum dots (GQDs), owing to their unique morphology, ultra-small lateral sizes, and exceptional properties, hold great promise for many applications, especially in the biomedical field. In this work, the cellular internalization, distribution, and cytotoxicity of the GQDs are explored complementarily using transmission electron microscopy, confocal laser scanning microscopy, UV-vis, and fluorescence spectroscopies, and flow cytometry with human gastric cancer MGC-803 and breast cancer MCF-7 cells. It is demonstrated that the GQDs are internalized primarily through caveolae-mediated endocytosis. The effects of GQDs on the cell viability, internal cellular reactive oxygen species (ROS) level, mitochondrial membranes potential, and cell cycles show that the cytotoxicity of GQDs is lower than that of the micrometer-sized graphene oxide (GO). The low cytotoxicity and size consistence render GQDs appropriate for biomedical application.

Morphological changes of hippocampus in neuropsin deficient mice

Graphene quantum dots (GQDs) have gained significant interest in recent years due to their potential for biomedical applications, owing to their distinctive and tunable photoluminescence properties, remarkable physicochemical properties, high photostability, good biocompatibility, and small size. This article aims to explain the state-of-the-art outcomes in this rapidly evolving field and to deliver critical insights which will lead to further progress. In this article, the latest developments on synthesis, functionalization, key features, and cytotoxicity of GQDs have been presented followed by providing a focused overview on their current biological applications. Challenges and prospects in the developments of GQDs for biological applications are also discussed.