Luminescent Carbon Quantum Dots Research Articles

ONE STEP GREEN SYNTHESIS OF CARBON QUANTUM DOTS AND ITS APPLICATION TOWARDS THE BIOELECTROANALYTICAL AND BIOLABELING STUDIES

A green luminescent carbon quantum dots were prepared from maltose by Microwave assisted method followed by passivation with NaOH (pH=7.4). The TEM measurement confirmed the average size of prepared carbon quantum dots to be 2nm. Surface characterization such as XPS, FTIR and Raman spectroscopy confirm that the functional groups (C=O, C-OH) were attached on the surface of sp2 hybridized carbon. Electrochemical characterization studies on carbon paste electrode (CPE) revealed that the synthesized carbon quantum dots showed higher electrocatalytic property, conductivity and surface area. Therefore, herein we report the synthesized carbon quantum dots could find its applicability as an electrochemical sensor for the detection of neurotransmitter, dopamine. Cyclic voltammetry and differential pulse voltammetry (DPV) was employed for the detection of DA in presence of common interferences like UA, and AA with carbon quantum dots modified carbon paste electrode. The developed sensor was effectively applied for the real sample analysis with satisfactory results. Moreover, biological studies in He La cell lines proclaimed that the cell viability was unaffected (100% viability) on incubation with the carbon dots. Significant cellular uptake as revealed by fluorescence imaging makes them suitable for cell labeling studies.

Low-Temperature Hydrothermal Synthesis of Green Luminescent Carbon Quantum Dots (CQD), and Optical Properties of Blends of the CQD with Poly(3-hexylthiophene)

Carbon quantum dots (CQD) emitting green photoluminescence (PL; emission peak at 500 nm) with satisfactory quantum yield (12.1%) were synthesized by a low-temperature hydrothermal method (90°C for 2 h) with l-ascorbic acid as carbon source and ethanediamine as catalyst. The as-prepared CQD dispersed readily in aqueous media, were of average diameter 6.2 nm, and their PL performance was excitation-independent. The photoluminescence wavelength of the CQD was pH-independent but the photoluminescence intensity was pH-dependent. Films of the composite materials poly(3-hexylthiophene) (P3HT) and the CQD were prepared by spin-coating and characterized by ultraviolet–visible absorption spectrophotometry and fluorescence spectrometry. The results revealed enhanced ultraviolet–visible absorption of the P3HT–CQD film compared with pure P3HT and substantially reduced PL intensity of the blend film. Experimental and theoretical results indicate the feasibility of using the CQD as a new acceptor material in polymeric photovoltaic devices.

Highly luminescent nitrogen-doped carbon quantum dots as effective fluorescent probes for mercuric and iodide ions

Nitrogen-doped carbon quantum dots (N-CQDs) prepared via a one-step hydrothermal reaction exhibited highly selective and sensitive detection of Hg2+ and I− through fluorescence quenching and recovery processes, respectively.

Synthesis of carbon quantum dots from cabbage with down- and up-conversion photoluminescence properties: excellent imaging agent for biomedical applications

The synthesis of luminescent and biocompatible carbon quantum dots is demonstrated from cabbage, a new carbonaceous biomaterial, for bio-imaging.

Down- and Up-Conversion Photoluminescence of Carbon-Dots from Brewing Industry Waste: Application in Live Cell-Imaging Experiments

Simple synthetic procedures have been applied to obtain luminescent carbon quantum dots, also referred as C-dots, from an abundant carbon source, that is, from the brewing industry waste. The synthetic procedures have been conducted aiming to investigate the effects of the oxidation stage on the properties of the nanomaterial. C-dots down- and up-conversion properties, as well as their potential for cellular imaging experiments in live (and adhered) cells, are disclosed herein.

Fast Microplasma Synthesis of Blue Luminescent Carbon Quantum Dots at Ambient Conditions

Fast, environmentally friendly synthesis of blue‐luminescent carbon quantum dots (C‐dots) at ambient conditions (i.e., room temperature and atmospheric pressure) is presented. The as synthesized C‐dots are of a relatively size uniform distribution with a peak at approximately 2.4 nm. The photoluminescence show that the emission peak of C‐dots shifts from 443 nm to more than 456 nm as the excitation sources is varied from 360–410 nm. The majority of C‐dots produced are predominantly graphitic in nature based on the Raman spectroscopy. The plasma‐assisted non‐equilibrium reactive chemistry induces chemical reactions and accelerates the C‐dot formation process.

One‐Pot Synthesis of Highly Luminescent Carbon Quantum Dots and Their Nontoxic Ingestion by Zebrafish for In Vivo Imaging

Photoluminescent carbon and/or silicon-based nanodots have attracted ever increasing interest. Accordingly, a myriad of synthetic methodologies have been developed to fabricate them, which unfortunately, however, frequently involve relatively tedious steps, such as initial surface passivation and subsequent functionalization. Herein, we describe a green and sustainable synthetic strategy to combine these procedures into one step and to produce highly luminescent carbon quantum dots (CQDs), which can also be easily fabricated into flexible thin films with intense luminescence for future roll-to-roll manufacturing of optoelectronic devices. The as-synthesized CQDs exhibited enhanced cellular permeability and low or even noncytotoxicity for cellular applications, as corroborated by confocal fluorescence imaging of HeLa cells as well as cell viability measurements. Most strikingly, zebrafish were directly fed with CQDs for in vivo imaging, and mortality and morphologic analysis indicated ingestion of the CQDs posed no harm to the living organisms. Hence, the multifunctional CQDs potentially provide a rich pool of tools for optoelectronic and biomedical applications.

Solution reduction synthesis of amine terminated carbon quantum dots

Highly luminescent water soluble carbon quantum dots (CQDs) with narrow size distributions have been prepared via a simple room temperature, solution-phase synthesis. The CQDs, stabilised by covalently bound allylamine ligands to minimise surface oxidation, exhibit an excitation wavelength dependent blue luminescence with a quantum yield of 25%.

Size controlled synthesis of carbon quantum dots using hydride reducing agents

Highly luminescent carbon quantum dots (CQDs) are synthesized at room temperature by hydride reduction of carbon tetrachloride within inverse micelles.

Efficient one-pot synthesis of highly monodisperse carbon quantum dots

Highly luminescent carbon quantum dots (CQDs) with narrow size distributions were synthesised in reverse micelles using a simple room temperature, solution-phase synthesis. The CQDs are stabilised by covalently bound alkyl ligand to minimise surface oxidation and exhibit blue emission with a marked dependency on excitation wavelength.

Nitrogen-doped carbon quantum dots: Facile synthesis and application as a “turn-off” fluorescent probe for detection of Hg2+ ions

A facile, economical and straightforward hydrothermal strategy is used to prepare highly luminescent nitrogen-doped carbon quantum dots (N-CQDs) by using folic acid as both carbon and nitrogen sources. The as-prepared N-CQDs have an average size of 4.5±1.0nm and exhibit excitation wavelength-dependent fluorescence with the maximum emission and excitation at 390 and 470nm, respectively. Furthermore, due to the effective quenching effect of Hg2+ ions, such N-CQDs are found to serve as an effective fluorescent sensing platform for lable-free sensitive detection of Hg2+ ions with a detection limit of 0.23μM. The selectivity experiments reveal that the fluorescent sensor is specific for Hg2+ even with interference by high concentrations of other metal ions. Most importantly, the N-CQDs-based Hg2+ ions sensor can be successfully applied to the determination of Hg2+ in tap water and real lake water samples. With excellent sensitivity and selectivity, such stable and cheap carbon materials are potentially suitable for monitoring of Hg2+ in environmental application.

Luminescent carbon quantum dots and their application in cell imaging

A facile hydrothermal method was used to synthesize luminescent carbon dots from single-walled carbon nanotubes (SWNTs). Then 4,7,10-trioxa-1,13-tridecanediamine (TTDDA) was grafted onto the carbon dots to increase their water solubility and luminescent properties. The as-prepared carbon dots were characterized by UV-Vis absorption, infrared (IR), Raman, fluorescence, and transmission electron microscopy (TEM). The results confirmed that these carbon dots were monodispersed in water and emitted bright yellow fluorescence. The surface modified carbon dots were used to label biological cells, and the images obtained by a laser scanning confocal microscope showed that the carbon dots were gradually taken up by HeLa cells. The cytotoxicity of such carbon dots toward HeLa cells was very low, for 24 h the LC50 was over 5 mg mL−1.

Highly luminescent biocompatible carbon quantum dots by encapsulation with an amphiphilic polymer

Highly luminescent, water-soluble and biocompatible Carbon Quantum Dots (aqCQDs) were prepared by encapsulating the parent hydrophobic CQDs in an amphiphilic polymer. The resulting aqCQDs were non-toxic to living cells, and were found to cross the cell membrane and localise primarily in the cytosol.

Facile synthesis of graphitic carbon quantum dots with size tunability and uniformity using reverse micelles

Highly luminescent graphitic carbon quantum dots (GQDs) are synthesized employing reverse micelles as nanoreactors. This method offers size tunability and narrow size distribution without any unpractical size separation process. Also, high quantum yields of maximum 35% at the 360 nm excitation wavelength are achieved.