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(a) van der Waals (vdW) force between GQDs (GOQDs) and cell membrane. (b) Electrostatic (Ele) interaction between GQDs (GOQDs) and cell membrane
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Since their discovery as one of the most promising materials in the 21st century, nanomaterials have been widely studied by the scientific community, where their biosafety remains the most concerning issue. Therefore, understanding the interactions between nanomaterials and living organisms is important. In this study, the mechanism of phospholipid...
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Graphene quantum dots (GQDs) have garnered significant attention, particularly in the biomedical domain. However, extensive research reveals a dichotomy concerning the potential toxicity of GQDs, presenting contrasting outcomes. Therefore, a comprehensive understanding of GQD biosafety necessitates a detailed supplementation of their toxicity profi...
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... Square-oxidized GQDs, rather than triangular-oxidized GQDs, continue to exhibit adaptive selfpropelling activity in the oxidized nanodomains, indicating that squareoxidized GQDs are more capable of self-propelling translocation. This is due to the "solvent-retention" effects resulting from the large amounts of solvent-accessible surface areas found in triangular-oxidized GQDs [49], as shown in Fig. 5C. Meanwhile, low membrane perturbation is observed when square-oxidized GQDs are compared to triangularoxidized GQDs, as illustrated by the two-dimensional number density in Fig. S8. ...
... Overall, spatially heterogeneous oxidation can be exploited as a self-propelled strategy to successfully translocate Janusshaped GQDs through biological membranes with a low free-energy barrier and minimal membrane perturbation. The biomedical field should further prioritize the precise regulation of the self-propelled motion strength and directionality of the translocating GQDs [49]. Besides, the synergistic effects of oxidized functional groups (i.e., hydroxyl, ether, and carboxyl groups) and cellular membrane composition on Janus-shape GQD translocation, in terms of internalization mechanism and cytotoxicity, are particularly crucial to analyze in the future [7]. ...
Although spatially heterogeneous oxidation is pivotal to the cellular translocation process of graphene quantum dots (GQDs), the dynamical road to the thermodynamically stable translocation conformation remains hazy. In this study, we illuminate the bio-interface doctrine involving the cellular translocation of Janus-shaped oxidized GQDs by performing multi-dimensional pathway computations predicated on coupled microsecond-long molecular dynamics and well-tempered metadynamics simulations. The oxidation nanodomains of Janus-shaped GQDs spontaneously yield hydrogen-bonds with polar lipid heads, while their pristine graphene nanodomains hy-drophobically associate with nonpolar lipid tails, and thus respond as self-propelled nanomotors across biological membranes. Hydrophobic-associations and hydrogen-bondings are found to be competitively coordinated, which dictates the dynamic pathway and thermodynamic states for cellular translocation, particularly modulating the adaptive self-propelling activity. The translocational phase diagram is drawn, demonstrating that GQDs with moderately square-patterned oxidation and thin thickness facilitate excellent translocation and minimal biological nanotoxicity. Importantly, intermolecular mechanochemistry is discovered to play a crucial role in energy transduction and nanomechanical interactions, which in turn affect the spatial rotation pathways of GQDs, as well as the membrane perturbations. Overall, this study provides an intuitive insight into the dynamics and thermodynamics of spontaneously translocating GQDs, opening up brand-new avenues for developing GQD-enabled nanocarriers or antibiotics.
Zero-dimensional (0D) nano-carbons, including graphene quantum dots, nanodiamonds, and carbon dots, represent the new generation of carbon-based nanomaterials with exceptional properties arising from diverse quantum phenomena, such as the surface, size, and edge effects, which strongly depend on the carbon–carbon bond configuration (sp2, sp3, and a mixture of sp2 and sp3) and particle size. Their unique physicochemical properties, including the optical, electronic, magnetic, reactivity, and catalytic properties, are valuable for energy conversion and storage, sensing, catalysis, optoelectronic devices, modern nanotechnologies, biomedical, and many other applications. This review aims to provide insights into the distinctive effects of 0D nano-carbon microstructures on their physicochemical properties that are crucial for cutting-edge fundamental studies and a broad range of multifunctional applications. The key synthesis methods for different types of 0D nano-carbons and current advances of characterization and computational techniques to study the structures of 0D nano-carbons and their structure–property relationships are also discussed. The review concludes with the current status, challenges, and future opportunities in this rapidly developing research field.
Graphene quantum dots (GQDs) coexist with antibiotic resistance genes (ARGs) in the environment. Whether GQDs influence ARG spread needs investigation, since the resulting development of multidrug‐resistant pathogens would threaten human health. This study investigates the effect of GQDs on the horizontal transfer of extracellular ARGs (i.e., transformation, a pivotal way that ARGs spread) mediated by plasmids into competent Escherichia coli cells. GQDs enhance ARG transfer at lower concentrations, which are close to their environmental residual concentrations. However, with further increases in concentration (closer to working concentrations needed for wastewater remediation), the effects of enhancement weaken or even become inhibitory. At lower concentrations, GQDs promote the gene expression related to pore‐forming outer membrane proteins and the generation of intracellular reactive oxygen species, thus inducing pore formation and enhancing membrane permeability. GQDs may also act as carriers to transport ARGs into cells. These factors result in enhanced ARG transfer. At higher concentrations, GQD aggregation occurs, and aggregates attach to the cell surface, reducing the effective contact area of recipients for external plasmids. GQDs also form large agglomerates with plasmids and thus hindering ARG entrance. This study could promote the understanding of the GQD‐caused ecological risks and benefit their safe application.
As a zero-dimensional (0D) nanomaterial, graphene quantum dot (GQD) has a unique physical structure and electrochemical properties, which has been widely used in biomedical fields, such as bioimaging, biosensor, drug delivery, etc. Its biological safety and potential cytotoxicity to human and animal cells have become a growing concern in recent years. In particular, the potential DNA structure damage caused by GQD is of great importance but still obscure. In this study, molecular dynamics (MD) simulation was used to investigate the adsorption behavior and the structural changes of single-stranded (ssDNA) and double-stranded DNA (dsDNA) on the surfaces of GQDs with different sizes and oxidation. Our results showed that ssDNA can strongly adsorb and lay flat on the surface of GQDs and graphene oxide quantum dots (GOQDs), whereas dsDNA was preferentially oriented vertically on both surfaces. With the increase of GQDs size, more structural change of adsorbed ssDNA and dsDNA could be found, while the size effect of GOQD on the structure of ssDNA and dsDNA is not significant. These findings may help to improve the understanding of GQD biocompatibility and potential applications of GQD in the biomedical field.
