L-cysteine functionalized graphene quantum dots for sub-ppb detection of As (III)

2021 ◽  
Author(s):  
Md. Farhan Naseh ◽  
Neelam Singh ◽  
Jamilur R. Ansari ◽  
Ashavani Kumar ◽  
Tapan Sarkar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Room Temperature ◽  
Graphene Quantum Dots ◽  
Optical Characterization ◽  
Functionalized Graphene ◽  
Transmission Electron ◽  
Sensitivity And Selectivity ◽  
Structural Characterizations

Abstract Here, we report functionalized graphene quantum dots (GQDs) for the optical detection of arsenic at room temperature. GQDs with the fluorescence of three fundamental colors (red, green, and blue) were synthesized and functionally capped with L-cysteine (L-cys) to impart selectively towards As (III) by exploiting the affinity of L-cys towards arsenite. The optical characterization of GQDs was carried out using UV-Vis absorption spectroscopy, Fourier transform infrared spectroscopy, and fluorescence spectrometry and the structural characterizations were performed using transmission electron microscopy. The fluorescence results showed instantaneous quenching in intensity when the GQDs came in contact with As (III) for all test concentrations over a range from 0.025 ppb to 25 ppb, which covers the permissible limit of arsenic in drinking water. The experimental results suggested excellent sensitivity and selectivity towards As (III).

Solvothermal Synthesis and Characterization of Lithium Tantalate Nanoparticles

2014 ◽  
Vol 602-603 ◽  
pp. 19-22 ◽  
Author(s):  
Lin Qiang Gao ◽  
Hai Yan Chen ◽  
Zhen Wang ◽  
Xin Zou
Keyword(s):  
Electron Microscopy ◽  
Solvothermal Synthesis ◽  
Room Temperature ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Particle Size And Morphology ◽  
Size And Morphology

Nanoscale LiTaO3 powders with perovskite structure were synthesized using the solvothermal technique with glycol as solvent at 240°C for 12h. The powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD was used to elucidate room temperature structures using Rietveld refinement. The powders were pure single pervoskite phase with high crystallinity. FESEM and TEM were used to determine particle size and morphology. The average LiTaO3 grain size was estimated to be < 200nm, and TEM images indicated that LiTaO3 particles had a brick-like morphology. In addition, the effect of the temperature on the LiTaO3 power characterisitics was also detailed studied.

scholarly journals GRAPHENE QUANTUM DOTS AS A REDUCING REAGENT AND STABILIZER FOR GREEN SYNTHESIS OF SILVER NANOPARTICLES: TOWARDS A HYDROGEN PEROXIDE AND GLUCOSE SENSOR

2018 ◽  
Vol 56 (1A) ◽  
pp. 146 ◽  
Author(s):  
Tran Vinh Hoang
Keyword(s):  
Hydrogen Peroxide ◽  
Quantum Dots ◽  
Silver Nanoparticles ◽  
Glucose Sensor ◽  
Graphene Quantum Dots ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Transmission Electron ◽  
Sensitivity And Selectivity ◽  
Signal Probe

In this work, we have developed a simple method for preparation of silver nanoparticles/graphene quantum dots hybrid (AgNPs/GQDs) using graphene quantum dots (GQDs) as reducing reagent and stabilizer. The synthesized GQDs and AgNPs/GQDs hybrid have been characterized by ultraviolet–visible spectroscopy (UV-Vis), photoluminescence (PL), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results indicated that mono-dispersed AgNPs were obtained with particles size around 30 nm. Based on the etching of silver nanoparticles by hydrogen peroxide (H2O2), we have constructed a colorimetric sensor for H2O2 and glucose sensors basing on the use of AgNPs/GQDs hybrid as capture probe and signal probe. The fabricated sensors performed excellent sensitivity and selectivity, high reproducibility for H2O2 and glucose detection with a low detection limit of 100 nM and 0.1 mM for hydrogen peroxide and glucose, respectively.

scholarly journals Characterization of Humidity Sensing of Polymeric Graphene-Quantum-Dots composites incorporated with silver nanowires

2017 ◽  
Vol 33 (3) ◽  
Author(s):  
Dinh Nguyen Nang ◽  
Lam Minh Long ◽  
Hoang Thi Thu ◽  
Huynh Tri Phong ◽  
Tran Quang Trung
Keyword(s):  
Quantum Dots ◽  
Relative Humidity ◽  
Room Temperature ◽  
Silver Nanowires ◽  
Graphene Quantum Dots ◽  
Composite Films ◽  
Bulk Heterojunctions ◽  
Humidity Sensing ◽  
Best Value

Graphene quantum dots (GQDs) were synthesized and incorporated with polyethylenedioxythiophene:poly(4-styrenesulfonate) (PEDOT:PSS), Ag  nanowires (AgNWs) to form a composite that can be used for enhancement of relative humidity (RH%) sensing. The composite films contained bulk heterojunctions of AgNW/GQD and AgNW/PEDOT:PSS. The sensors made from the composites responded well to relative humidity in a range from 10% to 50% at room temperature. With  an AgNWs content ranging from 0.2 wt.% to 0.4 wt.%  and 0.6 wt.%, the sensitivity of the relative humidity sensing devices based on AgNWs-doped GQDs+PEDOT:PSS composites was increased from 5.5% to 6.5 % and 15.2 %, respectively. The response time of the composite sensors was much improved due to AgNWs doping in the composites. For the 0.6 wt.% AgNWs-doped GQDs+PEDOT:PSS films, the best value of the recovery time was found to be of 30 s.

Synthesis and Characterization of Sliver Nanoparticles in KH-550 DMF Solution

2012 ◽  
Vol 557-559 ◽  
pp. 624-627
Author(s):  
Yan Ming Chen ◽  
Jiao Han
Keyword(s):  
Electron Microscopy ◽  
Silver Nanoparticles ◽  
Room Temperature ◽  
Synthesis And Characterization ◽  
Characteristic Surface ◽  
Surface Plasmon Band ◽  
Plasmon Band ◽  
Transmission Electron ◽  
Sliver Nanoparticles

Silver nanoparticles have been synthesized in 3-(aminopropyl)triethoxysilane (KH-550) solution using DMF (N, N-dimethylformamide) as both solvent and reductant at room temperature and 120°C. A characteristic surface plasmon band can be observed for the obtained silver nanoparticles from UV-vis absorption spectra, which indicate that KH-550 can serve as stabilizing agent for the formation of silver nanoparticles. Transmission electron microscopy (TEM) results show that silver nanoparticles with different sizes were obtained by simply controlling the reaction temperature.

Nanocrystalline and stacking-disordered β-cristobalite AlPO4 chemically stabilized at room temperature: synthesis, physical characterization, and X-ray powder diffraction data

2017 ◽  
Vol 32 (S1) ◽  
pp. S193-S200
Author(s):  
B. Peplinski ◽  
B. Adamczyk ◽  
P. Formanek ◽  
C. Meyer ◽  
O. Krüger ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Powder Diffraction ◽  
Title Compound ◽  
Room Temperature ◽  
Optical Emission ◽  
Xrd Pattern ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron

This paper reports the first successful synthesis and the structural characterization of nanocrystalline and stacking-disordered β-cristobalite AlPO4 that is chemically stabilized down to room temperature and free of crystalline impurity phases. Several batches of the title compound were synthesized and thoroughly characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy mapping in SEM, solid-state 31P nuclear magnetic resonance (31P-NMR) spectroscopy including the TRAPDOR method, differential thermal analysis (DTA), gas-sorption methods, optical emission spectroscopy, X-ray fluorescence spectroscopy, and ion chromatography. Parameters that are critical for the synthesis were identified and optimized. The synthesis procedure yields reproducible results and is well documented. A high-quality XRD pattern of the title compound is presented, which was collected with monochromatic copper radiation at room temperature in a wide 2θ range of 5°–100°.

RBS, TEM and SEM Characterization of Gold Nanoclusters in TiO2(110)

2003 ◽  
Vol 792 ◽  
Author(s):  
V. Shutthanandan ◽  
Y. Zhang ◽  
C. M. Wang ◽  
J. S. Young ◽  
L. Saraf ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Rutherford Backscattering Spectrometry ◽  
Gold Nanoclusters ◽  
Subsequent Annealing ◽  
Transmission Electron ◽  
Scanning Electron

ABSTRACTNucleation of gold nanoclusters in TiO2(110) single crystal using ion implantation and subsequent annealing were studied by Rutherford backscattering spectrometry /channeling (RBS/C), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Approximately 1000 Au2+/nm2 were implanted at room temperature in TiO2(110) substrates. TEM and SEM measurements reveal that rounded nanoclusters were formed during the implantation. In contrast, subsequent annealing in air for 10 hours at 1275 K promoted the formation of faceted (rectangular shaped) Au nanostructures in TiO2. RBS channeling measurements further reveled that Au atoms randomly occupied the host TiO2 lattice during the implantation. However, it appears that some Au atoms moved to the Ti lattice positions after annealing.

Synthesis and Characterization of Graphene/Cu2SnS3 Quantum Dots Composites

2012 ◽  
Vol 624 ◽  
pp. 59-62 ◽  
Author(s):  
Cai Xia Li ◽  
Jun Guo ◽  
Danyu Jiang ◽  
Qiang Li
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Raw Materials ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Structures ◽  
Transmission Electron

In this paper, employing Cu(AC)2•H2O, SnCl2•2H2O and thiourea as raw materials, the composites of graphene/Cu2SnS3 quantum dots (QDs) were prepared simply and quickly using the hydrothermal method. Meanwhile, the separate Cu2SnS3 QDs were also synthesized in the same way. The as-obtained Cu2SnS3 QDs and composites’ phase structures were analyzed and characterized by powder X-ray diffraction (XRD), and the results indicated that the size of the Cu2SnS3 QDs in the composites were less than that of the separate Cu2SnS3 QDs. At the same time, their morphologies were also observed and cross-confirmed by Transmission Electron Microscopy (TEM), and the measurements manifested that Cu2SnS3 QDs were uniformly dispersed on the surface of the graphene, while the separate Cu2SnS3 QDs have obvious glomeration. In addition to this, elemental analysis was also made to verify the existence of Cu2SnS3 on the surface of graphene.

scholarly journals Enzyme-Free Electrochemical Nano-Immunosensor Based on Graphene Quantum Dots and Gold Nanoparticles for Cardiac Biomarker Determination

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 578
Author(s):  
Bhargav D. Mansuriya ◽  
Zeynep Altintas
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Gold Nanoparticles ◽  
Troponin I ◽  
Electrochemical Techniques ◽  
Graphene Quantum Dots ◽  
High Specificity ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

An ultrasensitive enzyme-free electrochemical nano-immunosensor based on a screen-printed gold electrode (SPGE) modified with graphene quantum dots (GQDs) and gold nanoparticles (AuNPs) was engineered to detect cardiac troponin-I (cTnI) for the early diagnosis of acute myocardial infarction (AMI). The GQDs and in-house synthesized AuNPs were implanted onto the SPGE and allowed for anti-cTnI immobilization prior to quantifying cTnI. The biomarker could be determined in a wide concentration range using square-wave voltammetry (SWV), cyclic voltammetry (CV), electron impedance spectroscopy (EIS) and amperometry. The analyses were performed in buffer, as well as in human serum, in the investigation ranges of 1–1000 and 10–1000 pg mL−1, respectively. The detection time ranged from 10.5–13 min, depending on the electrochemical method employed. The detection limit was calculated as 0.1 and 0.5 pg mL−1 for buffer and serum, respectively. The sensitivity of the immunosensor was found to be 6.81 µA cm−2 pg mL−1, whereas the binding affinity was determined to be <0.89 pM. The sensor showed high specificity for cTnI with slight responses for nonspecific biomolecules. Each step of the sensor fabrication was characterized using CV, SWV, EIS and atomic force microscopy (AFM). Moreover, AuNPs, GQDs and their nanocomposites were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). This is the first immunosensor that represents the successful determination of an analyte using four different electrochemical techniques. Such a sensor could demonstrate a promising future for on-site detection of AMI with its sensitivity, cost-effectiveness, rapidity and specificity.

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