Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Fabrication of ultra-small monolayer graphene quantum dots by pyrolysis of trisodium citrate for fluorescent cell imaging.

ABSTRACT: The preparation and biological applications of ultra-small graphene quantum dots (GQDs) with accurate-controlled size are of great significance.Here in, we report a novel procedure involving pyrolysis of trisodium citrate and subsequent ultrafiltration for fabricating monolayer GQDs with ultra-small lateral size (1.3±0.5 nm).The GQDs exhibit blue photoluminescence with peak position independent of excitation wavelength. The quantum yield of GQDs is measured to be 3.6%, and the average fluorescence lifetime is 2.78 ns.Because of high stability and low toxicity, GQDs are demonstrated to be excellent bioimaging agents. The ultra-small GQDs can not only distribute in the cytoplasm but also penetrate into the nuclei. We ensure that this work will add a new dimension to the application of graphene materials for nanomedicine.

SUBMITTER: Hong GL

PROVIDER: S-EPMC6113908 | biostudies-other | 2018

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Publications

Fabrication of ultra-small monolayer graphene quantum dots by pyrolysis of trisodium citrate for fluorescent cell imaging.

Hong Guo-Lin GL Zhao Hai-Ling HL Deng Hao-Hua HH Yang Hui-Jing HJ Peng Hua-Ping HP Liu Yin-Huan YH Chen Wei W

International journal of nanomedicine 20180824

<h4>Background</h4>The preparation and biological applications of ultra-small graphene quantum dots (GQDs) with accurate-controlled size are of great significance.<h4>Methods</h4>Here in, we report a novel procedure involving pyrolysis of trisodium citrate and subsequent ultrafiltration for fabricating monolayer GQDs with ultra-small lateral size (1.3±0.5 nm).<h4>Results</h4>The GQDs exhibit blue photoluminescence with peak position independent of excitation wavelength. The quantum yield of GQDs ...[more]

PMID: 30197516

Similar Datasets

Electrostatically Confined Monolayer Graphene Quantum Dots with Orbital and Valley Splittings.

Project description:The electrostatic confinement of massless charge carriers is hampered by Klein tunneling. Circumventing this problem in graphene mainly relies on carving out nanostructures or applying electric displacement fields to open a band gap in bilayer graphene. So far, these approaches suffer from edge disorder or insufficiently controlled localization of electrons. Here we realize an alternative strategy in monolayer graphene, by combining a homogeneous magnetic field and electrostatic confinement. Using the tip of a scanning tunneling microscope, we induce a confining potential in the Landau gaps of bulk graphene without the need for physical edges. Gating the localized states toward the Fermi energy leads to regular charging sequences with more than 40 Coulomb peaks exhibiting typical addition energies of 7-20 meV. Orbital splittings of 4-10 meV and a valley splitting of about 3 meV for the first orbital state can be deduced. These experimental observations are quantitatively reproduced by tight binding calculations, which include the interactions of the graphene with the aligned hexagonal boron nitride substrate. The demonstrated confinement approach appears suitable to create quantum dots with well-defined wave function properties beyond the reach of traditional techniques.

| S-EPMC5031393 | biostudies-literature

Fluorescent graphene quantum dots as traceable, pH-sensitive drug delivery systems.

Project description:Graphene quantum dots (GQDs) were rationally fabricated as a traceable drug delivery system for the targeted, pH-sensitive delivery of a chemotherapeutic drug into cancer cells. The GQDs served as fluorescent carriers for a well-known anticancer drug, doxorubicin (Dox). The whole system has the capacity for simultaneous tracking of the carrier and of drug release. Dox release is triggered upon acidification of the intracellular vesicles, where the carriers are located after their uptake by cancer cells. Further functionalization of the loaded carriers with targeting moieties such as arginine-glycine-aspartic acid (RGD) peptides enhanced their uptake by cancer cells. DU-145 and PC-3 human prostate cancer cell lines were used to evaluate the anticancer ability of Dox-loaded RGD-modified GQDs (Dox-RGD-GQDs). The results demonstrated the feasibility of using GQDs as traceable drug delivery systems with the ability for the pH-triggered delivery of drugs into target cells.

| S-EPMC4630193 | biostudies-literature

Multicolor Fluorescent Graphene Oxide Quantum Dots for Sensing Cancer Cell Biomarkers.

Project description:Onion-like carbon nanoparticles were synthesized from diamond nanoparticles to be used as the precursor for graphene oxide quantum dots. Onion-like carbon nanoparticles were exfoliated to produce two types of nanoparticles, graphene oxide quantum dots that showed size-dependent fluorescence and highly stable inner cores. Multicolor fluorescent quantum dots were obtained and characterized using different techniques. Polyacrylamide gel electrophoresis showed a range of emission wavelengths spanning from red to blue with the highest intensity shown by green fluorescence. Using high-resolution transmission electron microscopy, we calculated a unit cell size of 2.47 Å in a highly oxidized and defected structure of graphene oxide. A diameter of ca. 4 nm and radius of gyration of ca. 11 Å were calculated using small-angle X-ray scattering. Finally, the change in fluorescence of the quantum dots was studied when single-stranded DNA that is recognized by telomerase was attached to the quantum dots. Their interaction with the telomerase present in cancer cells was observed and a change was seen after six days, providing an important application of these modified graphene oxide quantum dots for cancer sensing.

| S-EPMC8205432 | biostudies-literature

Electrochemical Method To Prepare Graphene Quantum Dots and Graphene Oxide Quantum Dots.

Project description:In this study, we present the preparation of graphene quantum dots (GQDs) and graphene oxide quantum dots (GOQDs). GQDs/GOQDs are prepared by an easy electrochemical exfoliation method, in which two graphite rods are used as electrodes. The electrolyte used is a combination of citric acid and alkali hydroxide in water. Four types of quantum dots, GQD1-GQD4, are prepared by varying alkali hydroxide concentration in the electrolyte, while keeping the citric acid concentration fixed. Variation of alkali hydroxide concentration in the electrolyte results in the production of GOQDs. Balanced reaction of citric acid and alkali hydroxide results in the production of GQDs (GQD3). However, three variations in alkali hydroxide concentration result in GOQDs (GQD1, GQD2, and GQD4). GOQDs show tunable oxygen functional groups, which are confirmed by X-ray photoelectron spectroscopy. GQDs/GOQDs show absorption in the UV region and show excitation-dependent photoluminescence behavior. The obtained average size is 2-3 nm, as revealed by transmission electron microscopy. X-ray diffraction peak at around 10° and broad D band peak at 1350 cm-1 in Raman spectra confirm the presence of oxygen-rich functional groups on the surface of GOQDs. These GQDs and GOQDs show blue to green luminescence under 365 nm UV irradiation.

| S-EPMC6645081 | biostudies-literature

Top-Down Fabrication of Luminescent Graphene Quantum Dots Using Self-Assembled Au Nanoparticles

Project description:A new graphene quantum dot (GQD) fabrication method is

| S-EPMC9933239 | biostudies-literature

Theoretical Investigations of Optical Origins of Fluorescent Graphene Quantum Dots.

Project description:The optical properties of graphene quantum dots (GQDs) were investigated theoretically. We focused on the photoinduced charge transfer and electron-hole coherence of single-layer graphene in the electronic transitions in the visible regions. Surface functionalization with donor or acceptor groups produced a red shift in the absorption spectrum, and electrons and holes were highly delocalized. The recombination of excited, well-separated electron-hole (e-h) pairs can result in enhanced fluorescence. This fluorescence enhancement by surface functionalization occurs because of the decreased symmetry of the graphene resulting from the roughened structure of the surface-functionalized GQDs.

| S-EPMC4837401 | biostudies-other

A Novel Route to High-Quality Graphene Quantum Dots by Hydrogen-Assisted Pyrolysis of Silicon Carbide.

Project description:Graphene quantum dots (GQDs) can be highly beneficial in various fields due to their unique properties, such as having an effective charge transfer and quantum confinement. However, defects on GQDs hinder these properties, and only a few studies have reported fabricating high-quality GQDs with high crystallinity and few impurities. In this study, we present a novel yet simple approach to synthesizing high-quality GQDs that involves annealing silicon carbide (SiC) under low vacuum while introducing hydrogen (H) etching gas; no harmful chemicals are required in the process. The fabricated GQDs are composed of a few graphene layers and possess high crystallinity, few defects and high purity, while being free from oxygen functional groups. The edges of the GQDs are hydrogen-terminated. High-quality GQDs form on the etched SiC when the etching rates of Si and C atoms are monitored. The size of the fabricated GQDs and the surface morphology of SiC can be altered by changing the operating conditions. Collectively, a novel route to high-quality GQDs will be highly applicable in fields involving sensors and detectors.

| S-EPMC7075118 | biostudies-literature

Plasmonic fluorescent quantum dots.

Project description:Combining multiple discrete components into a single multifunctional nanoparticle could be useful in a variety of applications. Retaining the unique optical and electrical properties of each component after nanoscale integration is, however, a long-standing problem. It is particularly difficult when trying to combine fluorophores such as semiconductor quantum dots with plasmonic materials such as gold, because gold and other metals can quench the fluorescence. So far, the combination of quantum dot fluorescence with plasmonically active gold has only been demonstrated on flat surfaces. Here, we combine fluorescent and plasmonic activities in a single nanoparticle by controlling the spacing between a quantum dot core and an ultrathin gold shell with nanometre precision through layer-by-layer assembly. Our wet-chemistry approach provides a general route for the deposition of ultrathin gold layers onto virtually any discrete nanostructure or continuous surface, and should prove useful for multimodal bioimaging, interfacing with biological systems, reducing nanotoxicity, modulating electromagnetic fields and contacting nanostructures.

| S-EPMC2773548 | biostudies-literature

pH-Responsive fluorescent graphene quantum dots for fluorescence-guided cancer surgery and diagnosis.

Project description:Cancer remains a major cause of morbidity and mortality around the world. Improved cancer treatment requires enhancement of cancer diagnosis and detection. To achieve this goal, here we report a novel imaging probe, pH-responsive fluorescent graphene quantum dots (pRF-GQDs). pRF-GQDs were prepared by electrolysis of graphite rods in sodium p-toluenesulfonate acetonitrile solution. The resulting pRF-GQDs, which have minimal toxicity, display a sharp fluorescence transition between green and blue at pH 6.8, a pH matching the acidic extracellular microenvironment in solid tumors. We found that this unique fluorescence switch property allows tumors to be distinguished from normal tissues. In addition to fluorescence, pRF-GQDs also exhibit upconversion photoluminescence (UCPL). We demonstrate that the combination of UCPL and fluorescence switch enables detection of solid tumors of different origin at an early developmental stage. Therefore, pRF-GQDs have great potential to be used as a universal probe for fluorescence-guided cancer surgery and cancer diagnosis.

| S-EPMC5501082 | biostudies-literature

Size Fractionation of Fluorescent Graphene Quantum Dots Using a Cross-Flow Membrane Filtration System.

Project description:Graphene quantum dots (GQDs) have received great attention as optical agents because of their low toxicity, stable photoluminescence (PL) in moderate pH solutions, and size-dependent optical properties. Although many synthetic routes have been proposed for producing GQD solutions, the broad size distribution in GQD solutions limits its use as an efficient optical agent. Here, we present a straightforward method for size fractionation of GQDs dispersed in water using a cross-flow filtration system and a track-etched membrane with cylindrical uniform nanopores. The GQD aqueous suspension, which primarily contained blue-emitting GQDs (B-GQDs) and green-emitting GQDs (G-GQDs), was introduced to the membrane in tangential flow and was fractionated with a constant permeate flow of about 800 L m-2 h-1 bar-1. After filtration, we observed a clear blue PL spectrum from the permeate side, which can be attributed to selective permeation of relatively small B-GQDs. The process provided a separation factor (B-GQDs/G-GQDs) of 0.74. In the cross-flow filtration system, size-dependent permeation through cylindrical nanochannels was confirmed by simulation. Our results demonstrate a feasible method facilitating size fractionation of two-dimensional nanostructures using a cross-flow membrane filtration system. Since membrane filtration is simple, cost-effective, and scalable, our approach can be applied to prepare a large amount of size-controlled GQDs required for high performance opto-electronics and bio-imaging applications.

| S-EPMC6267503 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data