Graphene Oxide Quantum Dots Research Articles

Molecular interactions of the Omicron, Kappa, and Delta SARS-CoV-2 spike proteins with quantum dots of graphene oxide.

The Omicron, Kappa, and Delta variants are different strains of the SARS-CoV-2 virus. Graphene oxide quantum dots (GOQDs) represent a burgeoning class of oxygen-enriched, zero-dimensional materials characterized by their sub-20-nm dimensions. Exhibiting pronounced quantum confinement and edge effects, GOQDs manifest exceptional physical-chemical attributes. This study delves into the potential of graphene oxide quantum dots, elucidating their inherent properties pertinent to the surface structures of SARS-CoV-2, employing an integrated computational approach for the repositioning of inhibitory agents. Following rigorous adjustment tests, a spectrum of divergent bonding conformations emerged, with particular emphasis placed on identifying the conformation exhibiting optimal adjustment scores and interactions. The investigation employed molecular docking simulations integrating affinity energy evaluations, electrostatic potential clouds, molecular dynamics encompassing average square root calculations, and the computation of Gibbs-free energy. These values quantify the strength of interaction between GOQDs and SARS-CoV-2 spike protein variants. The receptor structures were optimized using the CHARM-GUI server employing force field AMBERFF14SB. The algorithm embedded in CHARMM offers an efficient interpolation scheme and automatic step size selection, enhancing the efficiency of the optimization process. The 3D structures of the ligands are constructed and optimized with density functional theory (DFT) method based on the most stable conformer of each binder. Autodock Vina Software (ADV) was utilized, where essential parameters were specified. Electrostatic potential maps (MEPs) provide a visual depiction of molecules' charge distributions and related properties. After this, molecular dynamics simulations employing the CHARM36 force field in Gromacs 2022.2 were conducted to investigate GOs' interactions with surface macromolecules of SARS-CoV-2 in an explicit aqueous environment. Furthermore, our investigation suggests that lower values indicate stronger binding. Notably, GO-E consistently showed the most negative values across interactions with different variants, suggesting a higher affinity compared to other GOQDs (GO-A to GO-D).

Amplified adsorption and photocatalytic degradation of polycyclic aromatic hydrocarbons using biocompatible nanocrystalline reduced graphene oxide quantum dots

Carcinogenic polycyclic aromatic hydrocarbons (PAHs) have been broadly recognized as significant organic pollutants in the environment, which pose a serious threat to both humans and animals. Therefore, there is an urgent need to develop a solution that effectively removes and reduces PAHs present in the environment. In the present work, we synthesized biocompatible nanocrystalline reduced graphene oxide quantum dots in powdered form (rGOQDTs) of crystallite size 2 nm through hydrothermal method and subsequently used for efficient adsorption and degradation of PAHs for the first time. We noticed that the adsorption of PAHs onto rGOQDTs was faster and more efficient as compared to adsorption on graphene oxide (GO). A 40-fold giant enhancement in the adsorption efficiency of Anthracene and Pyrene on rGOQDTs has been observed as compared to that of graphene oxide. We attribute this enormous enhancement in adsorption efficiency to the stacking of PAHs with rGOQDTs and stronger π-π interactions between rGOQDTs and PAHs. Interestingly, rGOQDTs also exhibit efficient photo-degradation of adsorbed PAHs under visible light irradiation and it degrades almost all PAHs after 80 min of visible light illumination. The degradation efficiency of PAHs is also higher for rGOQDTs as compared to GO. Our work paves the way for efficient removal and degradation of polycyclic aromatic hydrocarbons from the environment.

Next-generation membranes for verapamil removal: Graphene oxide quantum dot-modified polyethersulfone membranes

The presence of verapamil in water sources has gained attention due to its potential risks to ecosystems and human health. Because of its great separation performance and simplicity of integration into existing treatment processes, membrane filtration could be a viable alternative. Polyethersulfone (PES) membrane is usually employed for filtration processes due to its good mechanical and thermal stability. However, pristine PES membrane exhibits low flux and lower fouling properties due to its poor antibacterial properties. Thus, the phase inversion approach was used in the current study to develop graphene oxide quantum dots (GOQDs)-modified PES ultrafiltration (UF) membranes with varying quantities of GOQDs loading (0.01–0.07 wt%). With 0.03 wt% GOQDs, the PES composite membrane exhibited a water flux of 75.23 ±10.43 L/m2 h with a verapamil retention capability of 80.36%. All the modified PES membranes containing GOQDs exhibited the formation of inhibition zones, with PES-0.07 membranes (21.00 mm) showing more pronounced zones. The incorporation of GOQDs proved to be a promising and sustainable approach for modifying PES membranes, enhancing their flux, rejection performance, and antibacterial properties, which could be beneficial in removing pharmaceutical compounds from aqueous solution.

Visible-Light-Driven Photocatalytic H2 Production Using Composites of Co-Al Layered Double Hydroxides and Graphene Derivatives.

The direct conversion of solar energy into chemical energy represents an enormous challenge for current science. One of the commonly proposed photocatalytic systems is composed of a photosensitizer (PS) and a catalyst, together with a sacrificial electron donor (ED) when only the reduction of protons to H2 is addressed. Layered double hydroxides (LDH) have emerged as effective catalysts. Herein, two Co-Al LDH and their composites with graphene oxide (GO) or graphene quantum dots (GQD) have been prepared by coprecipitation and urea hydrolysis, which determined their structure and so their catalytic performance, giving H2 productions between 1409 and 8643 μmol g-1 using a ruthenium complex as PS and triethanolamine as ED at 450 nm. The influence of different factors, including the integration of both components, on their catalytic behavior, has been studied. The proper arrangement between the particles of both components seems to be the determining factor for achieving a synergistic interaction between LDH and GO or GQD. The novel Co-Al LDH composite with intercalated GQD achieved an outstanding catalytic efficiency (8643 μmol H2 g-1) and exhibited excellent reusability after 3 reaction cycles, thus representing an optimal integration between graphene materials and Co-Al LDH for visible light driven H2 photocatalytic production.

Visible-light driven photocatalytic degradation of organic dyes by carbonized palladium-impregnated graphene oxide quantum dots

In this study, palladium impregnated graphene oxide quantum dots (Pd-GOQD) have been synthesized by biogenic carbonization. The formation of Pd-GOQD and GOQD was confirmed by physicochemical techniques such as Brunauer–Emmett–Teller (BET), photoluminescence spectroscopy, XRD, Raman spectroscopy, XPS analysis, and HAADF-STEM analysis. TEM analysis revealed that GOQD and Pd-GOQD are spherical, with a mean size of around 2.9 and 3.7 nm, respectively. The photocatalytic activities of Pd-GOQD and GOQD using methylene blue (MB) and methyl orange (MO) dye under visible light were investigated using spectroscopic analysis. Pd-GOQD showed nearly better dye degradation efficiency as 90% dye was reduced within 75 min compared to 50% efficiency of GOQD. Kinetic of the reduction process of MB and MO was well correlated with first-order kinetics. Besides, the Pd-GOQD exhibited its regeneration and reusability as its photo-degradation performance remained unaffected after five successive reuses. Hence GO-Pd nanocomposite was a promising option for removing synthetic dyes from aqueous solutions.

Nanotechnology's Applications and Potential in Various Fields.

Since ancient times, several sorts of nanoparticles have been employed in the quickly expanding field of nanotechnology. These features include size, shape, and chemical as well as physical properties.Because of their small size and huge surface area, carbon-based nanoparticles, including fullerenes, carbon nanotubes, graphene, graphene oxide, and carbon-based quantum dots, have attracted a lot of attention in a variety of sectors, including biomedical applications. Lipid bilayers form the spherical vesicles known as liposomes. Magnetic resonance imaging (MRI) contrast agents are iron oxide nanoparticles. These materials are perfect for drug and delivery of genes, bioimaging, and bone repair because of their remarkable mechanical, electrical, visual, and chemical properties. However, concerns about potential asbestos-related diseases have arisen due to their length-to-width aspect ratio. Ceramic nanoparticles, on the other hand, are a common material in daily life and play a crucial role in bone repair, multiscale hybridisation, and aerospace structures. These nanoparticles can enhance osseointegration and bone development by mimicking the nanocomposition and nanoscale characteristics of bone tissue and enhance osteoconductive and osteoinductive capacities. Ceramic nanoparticles, however, have the potential to generate oxidative stress, which can result in irritation of the reticuloendothelial system, cytotoxicity to the heart, liver, and lungs, as well as toxicity to the cells that are attached. Additionally, oxidative stress, cell damage, and genotoxicity might result from the generation of free radicals by ceramic nanoparticles. Metal nanoparticles exhibit linear optical properties similar to molecular systems but arise from a different physical process. Semiconductor nanocrystals (NCs) are made from various compounds, such as silicon and germanium. Polyandry nanoparticles are particles approximately 10 and 10000 nanometers (nm) in size that can contain active substances. They have applications in vaccine delivery, gene therapy, and polymer nanoparticles (nanomedicine) for therapeutic applications.

High-performance cementitious composites containing nanostructured carbon additives made from charred coal fines.

Carbon-based nanomaterials, such as carbon nanoplatelets, graphene oxide, and carbon quantum dots, have many possible end-use applications due to their ability to impart unique mechanical, electrical, thermal, and optical properties to cement composites. Despite this potential, these materials are rarely used in the construction industry due to high material costs and limited data on performance and durability. In this study, domestic coal is used to fabricate low-cost carbon nanomaterials that can be used economically in cement formulations. A range of chemical and physical processing approaches are employed to control the size, morphology, and chemical functionalization of the carbon nanomaterial, which improves its miscibility with cement formulations and its impact on mechanical properties and durability. At loadings of 0.01 to 0.07wt.% of coal-derived carbon nanomaterial, the compressive and flexural strength of cement samples are enhanced by 24% and 23%, respectively, in comparison to neat cement. At loadings of 0.02 to 0.06wt.%, the compressive and flexural strength of concrete composites increases by 28% and 21%, respectively, in comparison to neat samples. Additionally, the carbon nanomaterial additives studied in this work reduce cement porosity by 36%, permeability by 86%, and chloride penetration depth by 60%. These results illustrate that low-loadings of coal-derived carbon nanomaterial additives can improve the mechanical properties, durability, and corrosion resistance of cement composites.

Thermo-optic characterization of graphene oxide quantum dot semiconductors for the determination of quantum efficiency

Thermo-optic characterization of graphene oxide quantum dot semiconductors for the determination of quantum efficiency

Human periodontal ligament stem cell sheets activated by graphene oxide quantum dots repair periodontal bone defects by promoting mitochondrial dynamics dependent osteogenic differentiation

BackgroundBone defects in the maxillofacial region restrict the integrity of dental function, posing challenges in clinical treatment. Bone tissue engineering (BTE) with stem cell implants is an effective method. Nanobiomaterials can effectively enhance the resistance of implanted stem cells to the harsh microenvironment of bone defect areas by promoting cell differentiation. Graphene oxide quantum dots (GOQDs) are zero-dimensional nanoscale derivatives of graphene oxide with excellent biological activity. In the present study, we aimed to explore the effects of GOQDs prepared by two methods (Y-GOQDs and B-GOQDs) on the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs), as well as the effect of gelatin methacryloyl (GelMA)-encapsulated GOQD-induced hPDLSC sheets on the repair of mandibular periodontal defects in rats. We also explored the molecular biological mechanism through which GOQD promotes bone differentiation.ResultsThere were significant differences in oxygen-containing functional groups, particle size and morphology between Y-GOQDs and B-GOQDs. Y-GOQDs promoted the osteogenic differentiation of hPDLSCs more effectively than did B-GOQDs. In addition, GelMA hydrogel-encapsulated Y-GOQD-induced hPDLSC cell sheet fragments not only exhibited good growth and osteogenic differentiation in vitro but also promoted the repair of mandibular periodontal bone defects in vivo. Furthermore, the greater effectiveness of Y-GOQDs than B-GOQDs in promoting osteogenic differentiation is due to the regulation of hPDLSC mitochondrial dynamics, namely, the promotion of fusion and inhibition of fission.ConclusionsOverall, Y-GOQDs are more effective than B-GOQDs at promoting the osteogenic differentiation of hPDLSCs by regulating mitochondrial dynamics, which ultimately contributes to bone regeneration via the aid of the GelMA hydrogels in vivo.Graphical

Potential toxicity of graphene (oxide) quantum dots via directly covering the active site of anterior gradient homolog 2 protein

Graphene quantum dots (GQDs) have attracted significant attention in biomedicine, while extensive investigations have revealed a reverse regarding the potential biotoxicity of GQDs. In order to supplementing the understanding of the toxicity profile of GQDs, this study employs a molecular dynamics (MD) simulation approach to systematically investigate the potential toxicity of both GQDs and Graphene Oxide Quantum Dots (GOQDs) on the Anterior Gradient Homolog 2 (AGR2) protein, a key protein capable of protecting the intestine. We construct two typical simulation systems, in which an AGR2 protein is encircled by either GQDs or GOQDs. The MD results demonstrate that both GQDs and GOQDs can directly make contact with and even cover the active site (specifically, the Cys81 amino acid) of the AGR2 protein. This suggests that GQDs and GOQDs have the capability to inhibit or interfere with the normal biological interaction of the AGR2 active site with its target protein. Thus, GQDs and GOQDs exhibit potential detrimental effects on the AGR2 protein. Detailed analyses reveal that GQDs adhere to the Cys81 residue due to van der Waals (vdW) interaction forces, whereas GOQDs attach to the Cys81 residue through a combination of vdW (primary) and Coulomb (secondary) interactions. Furthermore, GQDs aggregation typically adsorb onto the AGR2 active site, while GOQDs adsorb to the active site of AGR2 one by one. Consequently, these findings shed new light on the potential adverse impact of GQDs and GOQDs on the AGR2 protein via directly covering the active site of AGR2, providing valuable molecular insights for the toxicity profile of GQD nanomaterials.

Enhancing Photothermal/Photodynamic Therapy for Glioblastoma by Tumor Hypoxia Alleviation and Heat Shock Protein Inhibition Using IR820-Conjugated Reduced Graphene Oxide Quantum Dots.

We use low-molecular-weight branched polyethylenimine (PEI) to produce cytocompatible reduced graphene oxide quantum dots (rGOQD) as a photothermal agent and covalently bind it with the photosensitizer IR-820. The rGOQD/IR820 shows high photothermal conversion efficiency and produces reactive oxygen species (ROS) after irradiation with near-infrared (NIR) light for photothermal/photodynamic therapy (PTT/PDT). To improve suspension stability, rGOQD/IR820 was PEGylated by anchoring with the DSPE hydrophobic tails in DSPE-PEG-Mal, leaving the maleimide (Mal) end group for covalent binding with manganese dioxide/bovine serum albumin (MnO2/BSA) and targeting ligand cell-penetrating peptide (CPP) to synthesize rGOQD/IR820/MnO2/CPP. As MnO2 can react with intracellular hydrogen peroxide to produce oxygen for alleviating the hypoxia condition in the acidic tumor microenvironment, the efficacy of PDT could be enhanced by generating more cytotoxic ROS with NIR light. Furthermore, quercetin (Q) was loaded to rGOQD through π-π interaction, which can be released in the endosomes and act as an inhibitor of heat shock protein 70 (HSP70). This sensitizes tumor cells to thermal stress and increases the efficacy of mild-temperature PTT with NIR irradiation. By simultaneously incorporating the HSP70 inhibitor (Q) and the in situ hypoxia alleviating agent (MnO2), the rGOQD/IR820/MnO2/Q/CPP can overcome the limitation of PTT/PDT and enhance the efficacy of targeted phototherapy in vitro. From in vivo study with an orthotopic brain tumor model, rGOQD/IR820/MnO2/Q/CPP administered through tail vein injection can cross the blood-brain barrier and accumulate in the intracranial tumor, after which NIR laser light irradiation can shrink the tumor and prolong the survival times of animals by simultaneously enhancing the efficacy of PTT/PDT to treat glioblastoma.

Graphene oxide quantum dots (GOQDs) induce behavioral disorders via the disturbance of kynurenine pathway in zebrafish larvae

The emergence of graphene quantum dots (GQDs) expands the use of graphene derivatives in nanomedicine for its direct therapeutic applications in treating neurodegeneration, inflammation, metabolic dysfunction, and among others. Nevertheless, the biosafety assessment of GQDs remains deficient mostly because of the diverse surface characteristics of the nanoparticles. Our prior work demonstrated that GQDs can induce strong thigmotactic effects in zebrafish larvae over a wide range of concentrations, yet the underlying metabolic mechanisms remain largely unknown. In this study, we conducted a further exploration about graphene oxide quantum dots (GOQDs) for its potential neurotoxic effect on the behaviors of zebrafish larvae by combining neurotransmitter-targeted metabolomics with locomotion analysis. After continuous exposure to a concentration gradient of GOQDs (12.5 - 25 – 50 – 100 - 200 μg/mL) for 7 days, the thigmotactic activities of zebrafish larvae were observed across all exposure concentrations relative to the control group, while the basal locomotor activities, including distance moved and average velocity, were significantly changed by low concentrations of GOQDs. Targeted metabolomics was performed using zebrafish larvae at 7 days post-fertilization (dpf) that were exposed to 12.5 and 200 μg/mL, both of which were found to perturb the kynurenine pathway by regulating the levels of kynurenine, 3-hydroxyanthranilic acid (3-HAA), and quinolinic acid (QA). Furthermore, the thigmotaxis of larval fish induced by GOQDs during exposure could be counteracted by supplementing Ro-61-8048, an agonist acting on kynurenine 3-monooxygenase (KMO). In conclusion, our study establishes the involvement of the kynurenine pathway in GOQDs-induced thigmotaxis, which is independent of the transcriptional modulation of glutamate receptor families.

Chondroitin sulfate/silk fibroin hydrogel incorporating graphene oxide quantum dots with photothermal-effect promotes type H vessel-related wound healing

Chronic wounds with bacterial infection present formidable clinical challenges. In this study, a versatile hydrogel dressing with antibacterial and angiogenic activity composite of silk fibroin (SF), chondroitin sulfate (CS), and graphene oxide quantum dots (GOQDs) is fabricated. GOQDs@SF/CS (GSC) hydrogel is rapidly formed through the enzyme catalytic action of horseradish peroxidase. With the incorporation of GOQDs both gelation speed and mechanical properties have been enhanced, and the photothermal characteristics of GOQDs in GSC hydrogel enabled bacterial killing through photothermal treatment (PTT) at ∼51 °C. In vitro studies show that the GSC hydrogels demonstrate excellent antibacterial performance and induce type H vessel differentiation of endothelial cells via the activated ERK1/2 signaling pathway and upregulated SLIT3 expression. In vivo results show that the hydrogel significantly promotes type H vessels formation, which is related to the collagen deposition, epithelialization and, ultimately, accelerates the regeneration of infected skin defects. Collectively, this multifunctional GSC hydrogel, with dual action of antibacterial efficacy and angiogenesis promotion, emerges as an innovative skin dressing with the potential for advancing in infected wound healing.

High surface area microporous carbon nanocubes from controlled processing of graphene oxide nanoribbons

A new, facile, and template-free method to prepare high surface area microporous carbon nanocubes (CNCs) from a mixture of graphene oxide nanoribbons (NRs), graphene oxide, and carbon dots is reported. The nanoribbons, approximately 30 nm wide and with lengths ranging from a few tens of nanometres up to several micrometres, were obtained from the oxidation of Black Pearls 2000 carbon black in nitric acid solution. The non-purified nanoribbons further contained additional fragments of graphene oxide, and of graphene oxide quantum dots. Slow pyrolysis of the nanoribbon mixture with slow heating rates, e.g., 3 °C/min, yielded carbon nanocubes approximately 250 nm in size with surface areas greater than 900 m2/g. Heating rates of 50 °C/min led to carbons with ∼800 m2/g surface area but bulk morphology. Precipitating the nanoribbons in potassium hydroxide solution, followed by carbonization, yielded microporous nanoparticle aggregates that were 20 nm in size with surface areas greater than 2000 m2/g. The particles exhibited complex, quasi-spherical morphology. Pyrolysis of other products obtained from oxidation in HNO3 of different grades of carbon black, specifically graphene oxide nanoparticles and quantum dots, yielded high surface area microporous carbons but with bulk morphology regardless of the processing conditions. Despite the lower surface area and pore volume of the CNCs in comparison to the nanospheres, the former contained ultramicropores that were highly accessible to CO2 as a molecular probe and had excellent selectivity of CO2 over N2. Hence, CNC materials have promising properties for applications where particle surface-to-volume ratios, high internal surface areas, and abundant super and ultramicropores are desired.

An ultralow hysteresis zwitterionic hydrogel crosslinked by functionalized graphene oxide quantum dots for dual-responsive flexible wearable sensors

Strain sensors based on polymer hydrogels have attracted more and more interest thanks to their superior hydrophilicity and high ionic conductivity. However, the hydrogels generally suffer from high hysteresis, which may cause inaccurate information feedback. Meanwhile, to fast detect heavy metal ions in water at anytime and anywhere and ensure water quality safety, simple and convenient wearable detection devices must be developed. Herein, a new zwitterionic polymer hydrogel (PTH-G) is prepared using trimethylamine N-oxide derivative and N-(2-hydroxyethyl) acrylamide as monomers and glycidyl methacrylate functionalized graphene oxide quantum dots as crosslinking points. As-prepared PTH-G hydrogel exhibits ultralow hysteresis (3.6 %) and can visually detect copper ions in water in time (detection limit: as low as 1 μM). To further enhance the application potential of PTH-G hydrogel, lithium chloride (LiCl) is added. As-prepared PTH-G/LiCl hydrogel presents outstanding ionic conductivity (26.4 S/m), anti-freezing, and moisturizing properties. The strain sensor constructed with the hydrogel exhibits high linear sensitivity (2.24), low detection limit (close to 0 % strain), and short response and recovery times (96 and 104 ms), and can distinguish various human motions. The presented work gives new insights for developing next-generation flexible wearable sensors.

Synthesis and Promising Applications of Graphene and Related Materials

In recent years, there has been extensive research on graphene and its derivatives, driven by their remarkable physicochemical and functional properties. Various forms of graphene, such as multi-layer graphene, graphene oxide, and graphene quantum dots, have shown immense potential to revolutionize multiple technologies. This review critically examines the synthesis and applications of graphene and related materials. In the synthesis section, we explore methods ranging from top-down techniques, which involve breaking down larger structures into graphene layers, to bottom-up approaches, where graphene is built up from smaller constituents. In the application segment, we comprehensively discuss the diverse uses of graphene and its derivatives. This includes their roles in electronic applications, energy storage systems, tribological applications, healthcare technologies, water desalination processes, and mechanical applications. By exploring various applications, we aim to highlight the wide-spread applications of graphene-based materials and their composites in shaping the future of multiple technologies.

Facile construction of magnetic solid-phase extraction of polyaniline blend poly(amidoamine) dendrimers modified graphene oxide quantum dots for efficient adsorption of polycyclic aromatic hydrocarbons in environmental water

An efficient magneto–adsorbent composed of polyaniline blend poly(amidoamine) dendrimers modified graphene oxide quantum dots and magnetic Fe3O4 particles (Fe3O4@PANI–PSS/PAMAM–QGO) for magnetic solid–phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs) in environmental water was synthesized. Fe3O4@PANI–PSS/PAMAM–QGO exhibited exceptional adsorption property for most PAHs analytes. The nanocomposite sorbent demonstrated a ferromagnetic behavior of 17.457 emu g−1, which is adequate for subsequent use in MSPE. Key parameters affecting the processes of adsorption and desorption, including the sorbent amount, vortex adsorption time, vortex extraction time, sample volume, a solvent for desorption and the solvent volume were all examined and optimized. The performance of MSPE using Fe3O4@PANI–PSS/PAMAM–QGO as adsorbent for four PAHs, including fluoranthene, acenaphthene, phenanthrene and pyrene were studied through high performance liquid chromatography equipped with spectrofluorometer. Under the optimal conditions, Fe3O4@PANI–PSS/PAMAM–QGO showed a wide linearity of 10–1,000 ng mL−1, low detection limit (LOD) ranging from 1.92 to 4.25 ng mL -1 and high accuracy (recoveries of 93.6–96.5 %). Enrichment factors up to 185 were achieved. Furthermore, Fe3O4@PANI–PSS/PAMAM–QGO exhibited good recyclability (10 times, RSDs ≤ 5.35%), while maintaining its high efficiency in the extraction of PAHs. The proposed method was successfully applied for environmental samples. Recoveries ranging from 81.2 to 106.2 % were obtained, indicating a low matrix effect and the robustness of the optimized MSPE method. Based on these features and under the optimal extraction conditions, Fe3O4@PANI–PSS/PAMAM–QGO was demonstrated to be a successful tool for the rapid and sensitive extraction of PAHs in the samples.

Highly Reliable Performance of Flexible Synaptic Devices Based on PVP-GO QD Nanocomposites Due to the Formation of Directional Filaments.

The metallic conductive filament (CF) model, which serves as an important conduction mechanism for realizing synaptic functions in electronic devices, has gained recognition and is the subject of extensive research. However, the formation of CFs within the active layer is plagued by issues such as uncontrolled and random growth, which severely impacts the stability of the devices. Therefore, controlling the growth of CFs and improving the performance of the devices have become the focus of that research. Herein, a synaptic device based on polyvinylpyrrolidone (PVP)/graphene oxide quantum dot (GO QD) nanocomposites is proposed. Doping GO QDs in the PVP provides a large number of active centers for the reduction of silver ions, which allows, to a certain extent, the growth of CFs to be controlled. Because of this, the proposed device can simulate a variety of synaptic functions, including the transition from long-term potentiation to long-term depression, paired-pulse facilitation, post-tetanic potentiation, transition from short-term memory to long-term memory, and the behavior of the "learning experience". Furthermore, after being bent repeatedly, the devices were still able to simulate multiple synaptic functions accurately. Finally, the devices achieved a high recognition accuracy rate of 89.39% in the learning and inference tests, producing clear digit classification results.

Graphene Oxide Quantum Dots-Preactivated Dental Pulp Stem Cells/GelMA Facilitates Mitophagy-Regulated Bone Regeneration.

In bone tissue engineering (BTE), cell-laden scaffolds offer a promising strategy for repairing bone defects, particularly when host cell regeneration is insufficient due to age or disease. Exogenous stem cell-based BTE requires bioactive factors to activate these cells. Graphene oxide quantum dots (GOQDs), zero-dimensional derivatives of graphene oxide, have emerged as potential osteogenic nanomedicines. However, constructing biological scaffolds with GOQDs and elucidating their biological mechanisms remain critical challenges. We utilized GOQDs with a particle size of 10 nm, characterized by a surface rich in C-O-H and C-O-C functional groups. We developed a gelatin methacryloyl (GelMA) hydrogel incorporated with GOQDs-treated dental pulp stem cells (DPSCs). These constructs were transplanted into rat calvarial bone defects to estimate the effectiveness of GOQDs-induced DPSCs in repairing bone defects while also investigating the molecular mechanism underlying GOQDs-induced osteogenesis in DPSCs. GOQDs at 5μg/mL significantly enhanced the osteogenic differentiation of DPSCs without toxicity. The GOQDs-induced DPSCs showed active osteogenic potential in three-dimensional cell culture system. In vivo, transplantation of GOQDs-preactivated DPSCs/GelMA composite effectively facilitated calvarial bone regeneration. Mechanistically, GOQDs stimulated mitophagy flux through the phosphatase-and-tensin homolog-induced putative kinase 1 (PINK1)/Parkin E3 ubiquitin ligase (PRKN) pathway. Notably, inhibiting mitophagy with cyclosporin A prevented the osteogenic activity of GOQDs. This research presents a well-designed bionic GOQDs/DPSCs/GelMA composite scaffold and demonstrated its ability to promote bone regeneration by enhancing mitophagy. These findings highlight the significant potential of this composite for application in BTE and underscore the crucial role of mitophagy in promoting the osteogenic differentiation of GOQDs-induced stem cells.

Highly emissive blue graphene quantum dots with excitation-independent emission via ultrafast liquid-phase photoreduction.

Graphene oxide quantum dots (GOQDs) are promising candidates for biomedical applications since they have lower toxicity and higher biocompatibility than traditional semiconductor quantum dots. However, oxygen functional groups such as epoxy and hydroxyl groups usually induce nonradiative relaxation, which leads to GOQDs exhibiting nonemissive properties. For the enhancement of the emission efficiency of GOQDs, the number of nonradiative relaxation sites should be reduced. This paper reports the synthesis of highly luminescent reduced GOQDs prepared by liquid-phase photoreduction (LPP-rGOQDs). First, GOQDs was fabricated from single-walled carbon nanotubes through chlorate-based oxidation and separation after acoustic cavitation. Subsequently, LPP-rGOQDs were obtained by liquid-phase photoreduction of the GOQD suspension under intense pulsed light irradiation. Liquid-phase photoreduction selectively reduced epoxy groups present on the basal plane of GOQDs, and hydrogenated the basal plane without removal of carbonyl and carboxyl groups at the edges of the GOQDs. Such selective removal of oxidative functional groups was used to control the reduction degree of GOQDs, closely related to their optical properties. The optimized LPP-rGOQDs were bright blue in color and showed quantum yields up to about 19.7%, which was 10 times the quantum yield of GOQDs. Furthermore, the LPP-rGOQDs were utilized to image a human embryonic kidney (HEK293A), and a low cytotoxicity level and satisfactory cell imaging performance were observed.