- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Graphene quantum dot based charge-reversal nanomaterial for nucleus-targeted drug delivery and efficiency controllable photodynamic therapy
摘要： Graphene quantum dots (GQD), the new zero-dimensional carbon nanomaterial, has been demonstrated as a promising material for biomedical applications due to its good biocompatibility and low toxicity. However, the integration of multiple therapeutic approaches into a nano-sized platform based on the GQD has not been explored yet to our best knowledge. In this report, we regulate the generation of reactive oxygen species (ROS) when using the GQD as a photosensitizer by varying the doping amount of nitrogen atoms to achieve efficiency controllable photodynamic therapy (PDT). On the other hand, charge-reversal (3-Aminopropyl) triethoxysilane (APTES) was employed to conjugate on the surface of GQD for nucleus targeting drug delivery for the first time. The treatment outcome of produced ROS and nucleus-targeting drug delivery was investigated by fluorescence imaging. The results demonstrated that the N-GQD-DOX-APTES in dual roles as a drug carrier and photosensitizer could achieve nucleus-targeting delivery and strong ROS production simultaneously. This approach provides a promising strategy for the development of multifunctional therapy in one nano platform for biomedical applications.
关键词： nucleus-targeted drug delivery,Graphene quantum dots,nitrogen doped graphene quantum dots,charge-reversal,photodynamic therapy
更新于2025-11-21 11:24:58
-
Highly sensitive and selective label-free detection of dopamine in human serum based on nitrogen-doped graphene quantum dots decorated on Au nanoparticles: Mechanistic insights through microscopic and spectroscopic studies
摘要： A rapid, facile and label-free sensing strategy is developed for the detection of dopamine (DA) in the real samples by exploiting nitrogen-doped graphene quantum dots (N-GQDs) decorated on Au nanoparticles (Au@N-GQD). The as-grown Au@N-GQD exhibits strong blue fluorescence at room temperature and the fluorescence intensity is drastically quenched in presence of DA in neutral medium. The mechanistic insight into the DA sensing by Au@N-GQDs is explored here by careful monitoring of the evolution of the interaction of Au NPs and N-GQDs with DA under different conditions through electron microscopic and spectroscopic studies. The highly sensitive and selective detection of DA over a wide range is attributed to the unique core-shell structure formation with Au@N-GQD hybrids. The quenching mechanism involves the ground state complex formation as well as electron transfer from N-GQDs. The presence of Au NPs in Au@N-GQD hybrids accelerates the quenching process (~14 fold higher than bare N-GQDs) by the formation of stable dopamine-o-quinone (DQ) in this present detection scheme. The fluorescence quenching follows the linear Stern-Volmer plot in the range 0-100 μM, establishing its efficacy as a fluorescence-based DA sensor with a limit of detection (LOD) 590 nM, which is ~27 fold lower than the lowest abnormal concentration of DA in serum (16 μM). This sensing scheme is also successively applied to trace DA in Brahmaputra river water sample with LOD 480 nM including its satisfactory recovery (95-112%). Our studies reveal a novel sensing pathway for DA through the core-shell structure formation and it is highly promising for the design of efficient biological and environmental sensor.
关键词： Dopamine,Fluorescence quenching,Nitrogen-doped graphene quantum dots,Colorimetric sensing,Core-shell structure,Gold nanoparticles
更新于2025-11-21 11:01:37
-
Microwave-assisted synthesis of graphene quantum dots and nitrogen-doped graphene quantum dots: Raman characterization and their optical properties
摘要： In this report we will present completely new results on the improvement of the graphene quantum dots (GQDs) and nitrogen-doped graphene quantum dots (N-GQD) production method, using the microwave with different power levels and durations, from citric acid and urea. This is a new and unprecedented method of fabrication. The use of microwave has allowed ultra-fast fabrication of GQDs and nitrogen doped GQDs. These GQDs had their characteristics identi?ed by Raman scattering spectra for the characteristic C–C graphene vibration mode (G-peak) and defects of GQDs (D-peak). The absorption spectra of GQDs samples were fabricated under different conditions, with the expectation of different sizes, to be compared and analyzed. These absorption spectra were also compared with those of the N-GQD produced under the same conditions. The absorption mechanism of GQDs and N-GQD will be presented in detail. Measurements of the photoluminescence (PL) spectra in GQDs and N-GQD have also been recorded and analyzed. The ?uorescence mechanism will be presented, explained, and compared with other international publications of other authors. Some of the TEM and HR-TEM images of these two samples were also presented to con?rm the shape, size and in-plane spacing lattice of the GQD structure.
关键词： graphene quantum dots (GQDs),PL spectra,nitrogen-doped graphene quantum dots (N-GQD),microwave,Raman spectra,absorption spectra
更新于2025-11-19 16:56:42
-
Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications
摘要： In this work, we utilize a bottom-up approach to synthesize nitrogen self-doped graphene quantum dots (NGQDs) from a single glucosamine precursor via an eco-friendly microwave-assisted hydrothermal method. Structural and optical properties of as-produced NGQDs are further modified using controlled ozone treatment. Ozone-treated NGQDs (Oz-NGQDs) are reduced in size to 5.5 nm with clear changes in the lattice structure and ID/IG Raman ratios due to the introduction/alteration of oxygen-containing functional groups detected by Fourier-transform infrared (FTIR) spectrometer and further verified by energy dispersive X-ray spectroscopy (EDX) showing increased atomic/weight percentage of oxygen atoms. Along with structural modifications, GQDs experience decrease in ultraviolet–visible (UV–vis) absorption coupled with progressive enhancement of visible (up to 16 min treatment) and near-infrared (NIR) (up to 45 min treatment) fluorescence. This allows fine-tuning optical properties of NGQDs for solar cell applications yielding controlled emission increase, while controlled emission quenching was achieved by either blue laser or thermal treatment. Optimized Oz-NGQDs were further used to form a photoactive layer of solar cells with a maximum efficiency of 2.64% providing a 6-fold enhancement over untreated NGQD devices and a 3-fold increase in fill factor/current density. This study suggests simple routes to alter and optimize optical properties of scalably produced NGQDs to boost the photovoltaic performance of solar cells.
关键词： photovoltaics,optical properties,ozone treatment,nitrogen-doped graphene quantum dots,solar cells
更新于2025-11-19 16:56:42
-
Determination of Thiourea by On–Off Fluorescence Using Nitrogen-Doped Graphene Quantum Dots
摘要： A thiourea-detecting fluorescence sensor with Hg2t as a switch was developed using nitrogen-doped graphene quantum dots (N-GQDs). The surface of N-GQDs had many organic functional groups on which Hg2t was effectively bound and turned off the fluorescence of the N-GQDs. The fluorescence of N-GQDs was turned on by the thiol functional group of thiourea that bound strongly with Hg2t and formed Hg2t/thiourea complexes. After constructing the sensor, the experimental conditions and parameters, such as the pH and Hg2t concentration, were investigated and optimized. Under the optimum conditions, the constructed fluorescence sensor showed high sensitivity to thiourea at concentrations from 0.5 to 14 mM with a low detection limit of 41.7 nM. The sensor also exhibited high specificity, excellent stability, and good reproducibility so that the determination of thiourea in various samples had acceptable values with good recoveries from 99% to 106%. The relative standard deviation was less than 4.1% (n ? 3).
关键词： thiourea,Fluorescence,nitrogen-doped graphene quantum dots (N-GQDs),Hg2t,sensor
更新于2025-11-14 17:04:02
-
Effects of nitrogen-dopant bonding states on liquid-flow-induced electricity generation of graphene: A comparative study
摘要： We fabricate, measure and compare the effects of the bonding states of dopant nitrogen atoms in graphene devices, specifically on the liquid-flow-induced electricity by these devices. We find that nitrogen doping enhances the voltage induced by liquid flow regardless of the nitrogen bonding state. However, different nitrogen bonding states affect graphene’s conductivity differently: while graphitic nitrogen is suitable for electricity-generation applications, pyridinic nitrogen is hopeless for this purpose, due to the formation of symmetry-breaking defects of the latter.
关键词： Water-graphene interface,Nitrogen doped graphene,Flow-induced electricity generation
更新于2025-09-23 15:22:29
-
Single Nickel Atoms Anchored on Nitrogen-Doped Graphene as a Highly Active Co-Catalyst for Photocatalytic H2 Evolution
摘要： Earth abundant nickel is a typical non-noble-metal cocatalyst used for photocatalytic hydrogen evolution (PHE). Ni nanoparticles, however, tend to aggregate during the hydrogen production process, significantly lowering their PHE activity. In this research, we report single nickel atoms anchored on nitrogen-doped graphene (Ni-NG) as a cocatalyst for PHE. We have demonstrated that Ni-NG is a robust and highly active cocatalyst for PHE from water. With only 0.0013 wt.% of Ni loading, the PHE activity of composite Ni-NG/CdS photocatalyst is 3.4 times greater than that of NG/CdS. The quantum efficiency of Ni-NG/CdS for PHE reaches 48.2% at 420 nm, one of the highest efficiencies for non-noble-metal based cocatalysts reported in literature. Photoluminescence spectral analyses and electrochemical examinations have indicated that Ni-NG coupled to CdS can serve not only as an electron storage medium to suppress electron-hole recombination, but also as an active catalyst for proton reduction reaction. Density functional theory calculation shows that the high activity of Ni-NG/CdS composite results from the single Ni atoms trapped in NG vacancies, which significantly reduces the activation energy barrier of the hydrogen evolution reaction. This approach may be valuable for developing robust and highly active noble-metal free cocatalysts for solar hydrogen production.
关键词： Non-noble Metal Cocatalyst,CdS,Photocatalytic Hydrogen Evolution,Nitrogen-Doped Graphene,Single Ni Atom Catalysts
更新于2025-09-23 15:21:21
-
Study on Nitrogen-Doped Graphene Ink and Its Effects on the Heat Dissipation for the LED Lamps
摘要： This study explored the application of nitrogen-doped graphene (NDG) ink to the coating of light-emitting diode (LED) lamps for the thermal management. Unlike the general solutions of graphene, the NDG ink used in this study was tuned with high electrical resistance and quietly suitable for the application of the LED lamp coating, which prevented the short circuit problem; besides, the NDG ink also provided a high heat dissipation effect to improve the performance of the LED lamp. The investigation of adhesion and resistance for the NDG ink were conducted by the cross-cut test and the four-point probe resistance measurement, respectively. Three types of LED lamps including the original lamp, fin-removed lamp, and NDG-ink coated (NGC) lamp were tested for the actual operating temperature distribution by K-type thermal couples and for the lumens by the integrating sphere. The results showed that the heat dissipation of the NGC lamp was better than that of the original lamp. In addition, the inspections for the properties of NDG powder were also performed by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and Raman spectroscopy. According to the inspectional results, the NDG powder had a percentage of nitrogen of about 3.8% by XPS, a surface roughness Rq of 0.9 nm by AFM, and over ten layers by Raman analysis. It showed that the NDG powder in this study belonged to the type of multi-layer graphene.
关键词： integrating sphere,heat dissipation,nitrogen-doped graphene,LED
更新于2025-09-23 15:19:57
-
Nitrogen-doped graphene-cerium oxide (NG-CeO <sub/>2</sub> ) photocatalyst for the photodegradation of methylene blue in waste water
摘要： This study shows a facile approach for the preparation of CeO2 nanoparticles decorated with porous nitrogen-doped graphene (NG) nanosheets for effective photocatalytic degradation of methylene blue (MB). NG nanosheets were first synthesized using a hydrothermal method and then nitrogen-doped graphene-cerium oxide (NG-CeO2) was prepared through mixing of cerium nitrate with different concentrations of NG under ultrasonication followed by hydrothermal treatment. The synthesized nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The photocatalytic activity of the synthesized nanocomposites was analyzed against MB dye. Results showed that the nanocomposites of NG-CeO2 have an average particle size of 20 nm. The as-prepared NG-CeO2 nanocomposites exhibited outstanding photocatalytic activity for dye degradation under visible light irradiation, which could be attributed to synergistic effects between the NG nanosheets and CeO2. The quantum of photodegradation increases with the increase of the NG content in the nanocomposites.
关键词： nitrogen-doped graphene,CeO2,methylene blue,photodegradation
更新于2025-09-23 15:19:57
-
Hydrothermal synthesis of manganese oxide and nitrogen doped graphene (NG-MnO <sub/>2</sub> ) nanohybrid for visible light degradation of methyl orange dye
摘要： MnO2 nanoparticles and its nanocomposite with nitrogen-doped graphene (NG) have been fabricated via simple hydrothermal synthesis procedure using water as a solvent. X-ray diffraction (XRD) analysis of the as-prepared samples was used to ascertain the phase purity and crystallite size. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to study the surface features and particle size of the synthesised samples. The photocatalytic ability of the methyl orange (MO) dye with bare MnO2 and its hybrid with nitrogen-doped graphene (NG-MnO2) wer compared with visible light prompted degradation of the dye in absence of these catalysts. The prepared nanohybrid (NG-MnO2) showed improved photocatalytic efficacy as compared to the pure MnO2 nanoparticles. The strong ferromagnetic character of nanohybrid helps in easy separation of catalyst even with a bar magnet.
关键词： photodegradation,MnO2 nanoparticles,nitrogen-doped graphene,Methyl orange,visible light
更新于2025-09-19 17:15:36