scholarly journals Bioconjugation Between CdTe Quantum Dots and a Cationic Protein: An Analytical Method to Determine Protamine in Drug and Urine Samples

2021 ◽  
Author(s):  
Karolayne da Costa ◽  
Uéslen Rocha ◽  
Tasso Sales ◽  
Josué Santos
Keyword(s):  
Quantum Dots ◽  
Limit Of Detection ◽  
Interaction Mechanism ◽  
Cdte Quantum Dots ◽  
Urine Samples ◽  
Photoluminescence Intensity ◽  
Cationic Protein ◽  
Synthesis Time ◽  
Mercaptosuccinic Acid ◽  
Relative Standard

CdTe quantum dots (QD-CdTe) functionalized with mercaptosuccinic acid (MSA) were synthesized in an aqueous medium, varying synthesis time from 0.5 to 4 h. The nanoprobe were characterized by a direct relationship between synthesis time and QD size (2.61-3.04 nm). The QD-CdTe-MSA interacted with protamine (PT), a cationic protein, forming a bioconjugate, thus quenching the photoluminescence intensity and generating an on-off system. The nanoprobe produced at a synthesis time of 1 h (QD-CdTe1) presented PT’s best sensitivity in a succinate buffer (pH = 5). Under the optimized conditions, the proposed method presented a linear range of 0.05-0.5 mg L-1 (10-100 nM), limit of detection (LOD) 0.01 mg L-1 (2 nM), and relative standard deviation (RSD) ≤ 2.01% (n = 10). The interaction of the nanoprobe and PT led to aggregation due to a bioconjugate formation. The systems’ hydrodynamic radius varied from 4.31 nm (QD‑CdTe1) to 30.50 nm for the bioconjugate (QD-CdTe1-PT). The method was sensitive to variation in ionic strength and based on thermodynamic parameters; it was demonstrated that the interaction mechanism occurred preferentially through electrostatic forces. Finally, the method proved to be fast, sensitive, and viable for quantifying PT in drugs and synthetic urine samples with recoveries above 95%.

A simple paper-based approach for arsenic determination in water using hydride generation coupled with mercaptosuccinic-acid capped CdTe quantum dots

2020 ◽  
Vol 12 (21) ◽  
pp. 2718-2726
Author(s):  
Oraphan Thepmanee ◽  
Kanlaya Prapainop ◽  
Obnithi Noppha ◽  
Nuanlaor Rattanawimanwong ◽  
Weena Siangproh ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Hydride Generation ◽  
Cdte Quantum Dots ◽  
Mercaptosuccinic Acid ◽  
Cdte Qds ◽  
Arsenic Detection ◽  
Detection Probe ◽  
Arsenic Determination

Paper-based device with MSA-CdTe QDs as arsenic detection probe is presented.

scholarly journals Rapid and Sensitive Spectrophotometric Method for the Determination of the Trace Amount of Thallium (III) in Water and Urine Samples by New Oxidative Coupling Reaction

2019 ◽  
Vol 53 (4) ◽  
Author(s):  
Padmarajaiah Nagaraja ◽  
Naef Ghllab Saeed Al-Tayar ◽  
Anantharaman Shivakumar ◽  
Ashwinee Kumar Shresta ◽  
Avinash K. Gowda
Keyword(s):  
Spectrophotometric Method ◽  
Limit Of Detection ◽  
Rapid Determination ◽  
Coupling Reaction ◽  
Molar Absorptivity ◽  
Urine Samples ◽  
Oxidative Coupling Reaction ◽  
Relative Standard ◽  
Student’S T

A very simple, sensitive and fairly selective direct spectrophotometric method is presented for the rapid determination of thallium(III) at trace level. The method is based on the oxidation of 2-hydrazono-3-methyl-2,3-dihydrobenzo[d]thiazole hydrochloride (MBTH) by thallium(III) in phosphoric acid medium to form a diazoniumcation, which couples immediately with 10,11-dihydro-5Hdibenzo[b,f]azepine (IDB) at room temperature giving a blue colored species having a maximum absorption at 660 nm. The reaction conditions and other important analytical parameters were optimized.The calibration curve was found to be linear over the range of 0.1-4 μg/mL with molar absorptivity of 4.5 × 104 L mol- cm-1 and Sandell’s sensitivity of 0.00454 μg cm-2. The relative standard deviation and limit of detection have been found to be 0.58% and 0.0147 μg/mL respectively. Almost all common anions and cations are found notto interfering in matrix level of the analytical process. The method has been successfully applied for the determination of thallium(III) in synthetic standard mixtures, water and human urine samples. The performance of proposed method was evaluated in terms of student’s t-test and variance ratio F-test, to find out the significance of proposed method over the reported methods.    

Effect of Mercaptosuccinic Acid Stabilizer Agent on the Optical Properties of Colloidal CdTe Quantum Dots

2018 ◽  
Vol 18 (1) ◽  
pp. 651-658 ◽  
Author(s):  
J. C. L Sousa ◽  
M. G Vivas ◽  
B. R. C Vale ◽  
J. L Ferrari ◽  
d M. A Schiavon
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Cdte Quantum Dots ◽  
Mercaptosuccinic Acid

Tandem determination of mitoxantrone and ribonucleic acid using mercaptosuccinic acid-capped CdTe quantum dots

2017 ◽  
Vol 190 ◽  
pp. 254-260 ◽  
Author(s):  
Arash Mohammadinejad ◽  
Zarrin Es'haghi ◽  
Khalil Abnous ◽  
Seyed Ahmad Mohajeri
Keyword(s):  
Quantum Dots ◽  
Ribonucleic Acid ◽  
Cdte Quantum Dots ◽  
Mercaptosuccinic Acid

Facile Synthesis and Properties of Aqueous CdTe Quantum Dots for High-Sensitive Copper (II) Ion Detection

NANO ◽  
2017 ◽  
Vol 12 (12) ◽  
pp. 1750151 ◽  
Author(s):  
Yue Zheng ◽  
Hengshan Tang ◽  
Xiaoyu Wang ◽  
Ya Di ◽  
Kunling Lu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Limit Of Detection ◽  
Tap Water ◽  
High Sensitivity ◽  
Cdte Quantum Dots ◽  
Reaction Conditions ◽  
One Pot ◽  
Sensing System ◽  
Cdte Qds ◽  
Transmission Electron

The synthesis of aqueous MPA-capped CdTe quantum dots (QDs) via a facile one-pot route was developed. The particle size, optical properties and crystal structure of the as-synthesis QDs were investigated by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), UV-vis absorption and photoluminescence (PL) spectra, respectively. Meanwhile, the effect of reaction conditions, including reaction time, pH and the quantity of sodium citrate (SC) on the growth of CdTe QDs were discussed. Then, the obtained CdTe QDs were successfully used for the detection of trace Cu[Formula: see text] with high sensitivity and excellent selectivity. The fluorescence intensity of CdTe QDs with Cu[Formula: see text] concentration showed a linear relationship in the range from [Formula: see text] mol/L to [Formula: see text][Formula: see text]mol/L. The correlation coefficient (R) is 0.9980 and limit of detection (LOD) is [Formula: see text][Formula: see text]mol/L. Moreover, the concentration of Cu[Formula: see text] in tap water samples was determined based on this sensing system and the recovery test was satisfactory.

scholarly journals Dual-Emission Fluorescence Probe Based on CdTe Quantum Dots and Rhodamine B for Visual Detection of Mercury and Its Logic Gate Behavior

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 713
Author(s):  
Yuefeng Gao ◽  
Sai Xu ◽  
Zhijian Liu ◽  
Kezhen Yu ◽  
Xinxiang Pan
Keyword(s):  
Quantum Dots ◽  
Rhodamine B ◽  
Visual Detection ◽  
Fluorescence Probe ◽  
Limit Of Detection ◽  
Logic Gate ◽  
Cdte Quantum Dots ◽  
Fluorescence Signal ◽  
Dual Emission ◽  
Cdte Qds

It is urgent that a convenient and sensitive technique of detecting Hg2+ be developed because of its toxicity. Conventional fluorescence analysis works with a single fluorescence probe, and it often suffers from signal fluctuations which are influenced by external factors. In this research, a novel dual-emission probe assembled through utilizing CdTe quantum dots (QDs) and rhodamine B was designed to detect Hg2+ visually. Only the emission of CdTe QDs was quenched after adding Hg2+ in the dual-emission probe, which caused an intensity ratio change of the two different emission wavelengths and hence facilitated the visual detection of Hg2+. Compared to single emission QDs-based probe, a better linear relationship was shown between the variation of fluorescence intensity and the concentration of Hg2+, and the limit of detection (LOD) was found to be11.4 nM in the range of 0–2.6 μM. Interestingly, the intensity of the probe containing Hg2+ could be recovered in presence of glutathione (GSH) due to the stronger binding affinity of Hg2+ towards GSH than that towards CdTe QDs. Based on this phenomenon, an IMPLICATION logic gate using Hg2+/GSH as inputs and the fluorescence signal of QDs as an output was constructed.

Development of Dispersive Liquid-Liquid Microextraction Procedure for Trace Determination of Malathion Pesticide in Urine Samples

2020 ◽  
Author(s):  
Maryam RAMIN ◽  
Monireh KHADEM ◽  
Fariborz OMIDI ◽  
Mehran POURHOSEIN ◽  
Farideh GOLBABAEI ◽  
...  
Keyword(s):  
Enrichment Factor ◽  
Human Urine ◽  
High Performance ◽  
Limit Of Detection ◽  
Urine Samples ◽  
Human Urine Samples ◽  
Extraction Solvent ◽  
Ultraviolet Detector ◽  
Relative Standard

Background: Measurement of pesticides in biological matrices is become a serious challenge for researches because of their very low concentration in different matrices. The aim of this study was to develop a new sample preparation method with high accuracy and validity, simplicity and short retention time for determination of malathion. Methods: Dispersive liquid-liquid micro-extraction (DLLME) technique coupled with high-performance liquid chromatography equipped with ultraviolet detector (HPLC-UV) developed for trace extraction and determination of malathion pesticide in human urine samples. This study was done in 2017 at Tehran University of Medical Sciences, Tehran, Iran. One variable at a time (OVAT) method was used to optimize parameters affecting the malathion extraction. Different parameters such as extraction solvent, disperser solvent, and volume of the extraction solvent, volume of the disperser solvent, centrifugation time and speed, salt addition, and sample pH were studied and optimized. Results: Under the optimized conditions, the limit of detection and enrichment factor of the method were 0.5 µg L-1 and 200, respectively. The calibration curve was linear in the concentration range of 2-250 µg L-1 . The relative standard deviation for six replicate experiments at 200 µg L-1 concentration was less than 3%. The relative recoveries of spiked urine samples were 96.3%, 101.7% and 97.3% at three different concentration levels of 50, 200 and 1000 µg L-1 , respectively. Conclusion: DLLME procedure was successfully developed for the extraction of malathion from human urine samples. Compared to other extraction techniques, the proposed procedure had some advantages such as shorter extraction time, better reproducibility, and higher enrichment factor.  

scholarly journals A Simple Pre-concentration Method for the Determination of Nickel(II) in Urine Samples Using UV-Vis Spectrophotometry and Flame Atomic Absorption Spectrometry Techniques

2019 ◽  
Vol 19 (3) ◽  
pp. 638 ◽  
Author(s):  
Ahmed Fadhil Khudhair ◽  
Mouyed Khudhair Hassan ◽  
Hasan F. Alesary ◽  
Ahmed S. Abbas
Keyword(s):  
Limit Of Detection ◽  
Ph Effect ◽  
Absorption Spectrometry ◽  
Bath Temperature ◽  
Urine Samples ◽  
Ionic Surfactant ◽  
Concentration Method ◽  
Flame Atomic Absorption ◽  
Relative Standard ◽  
Triton X

The cloud point technique was effectively utilized for extraction and pre-concentration of nickel(II) in urine samples before measurement by UV-Vis spectrophotometer and AAS techniques. The metal response to a para-aminophenol (PAP) reagent in a non-ionic surfactant Triton X-114 medium was to form the Ni-PAP complex. The adopted concentration for PAP, concentration of Triton X-114, pH effect and water bath temperature, incubation time, salt effect, and interference effects were all optimized. The calibration curve was linear over the range of (0.0625–1.25) mg L–1 with a correlation coefficient r2 of 0.9682 for the UV-Vis spectrophotometer at a λmax of 629 nm. The limit of detection was 0.005 mg/L. The relative standard deviation for six replicates was 1.07%. This method was applied successfully to determine copper (II) concentrations in 44 urine samples of occupational worker samples as determined by UV-Vis spectrophotometry and FAAS techniques.

A green one-pot synthesis of nitrogen and sulfur co-doped carbon quantum dots for sensitive and selective detection of cephalexin

2017 ◽  
Vol 95 (6) ◽  
pp. 641-648 ◽  
Author(s):  
Farhad Akhgari ◽  
Naser Samadi ◽  
Khalil Farhadi ◽  
Mehrdad Akhgari
Keyword(s):  
Quantum Dots ◽  
Carbon Dots ◽  
Limit Of Detection ◽  
Carbon Quantum Dots ◽  
Water Soluble ◽  
Soluble Nitrogen ◽  
Selective Detection ◽  
Photoluminescence Intensity ◽  
Doped Carbon Dots ◽  
Co Doped

The article reports a simple, economic, and green method for preparing water-soluble, nitrogen and sulfur co-doped carbon quantum dots via a one-step hydrothermal method. Pomegranate juice served as the carbon source, and the L-cysteine provided nitrogen and sulfur. Co-doped carbon dots were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy techniques. The co-doped carbon dots served as fluorescent probes for sensitive and selective detection of cephalexin. Briefly, the co-doped carbon dot systems showed quenching of photoluminescence intensity in the presence of cephalexin. The decrease of fluorescence intensity made it possible to analyze cephalexin with satisfactory detection limits and linear ranges. The Sterne–Volmer plot showed a linear relationship (R2 = 0.998) between F0/F and the concentration of cephalexin over the range from 0.3 to 10 μmol L−1. The limit of detection (LOD) was estimated to be 1 × 10−7 mol L−1 (at a signal to noise ratio of 3). To validate the applicability, the described method was successfully applied for the detection of cephalexin in human urine and raw milk samples.

Sign in / Sign up

Export Citation Format

Share Document