scholarly journals Surface-modified Colloid CdTe/CdS Quantum Dots by a Biocompatible Thiazolidine Derivative as Promising Platform for Immobilization of Glucose Oxidase: Application to Fluorescence Sensing of Glucose

Author(s):  
Rahman Hallaj ◽  
Zahra Hosseinchi

Abstract This work focuses on the synthesis of novel modified core-shell CdTe/CdS quantum dots (QDs) and develops as a fluorescence sensor for glucose determination. The (E)-2,2'-(4,4'-dioxo-2,2'-dithioxo-2H,2'H-[5,5'-bithiazolylidene]-3,3'(4H,4'H)-diyl)bis(3- mercaptopropanoic acid) (DTM) as a new derivative of thiazolidine was synthesized and characterized and used to surface-modification of CdTe/CdS QDs. DTM-capped CdTe/CdS QDs used to immobilization of glucose oxidase (GOD). The intensity fluorescence emission of the CdSe/CdS-DTM/GOD is highly sensitive to the concentration of H2O2 as a byproduct of the catalytic oxidation of glucose. The experimental results showed that the quenched fluorescence was proportional to the glucose concentration within the range of 10 nM − 0.32 µM under optimized experimental conditions. The limit of detection of this system was found to be 4.3 nM. Compared with most of the existing methods, this newly developed system possesses many advantages, including simplicity, low cost, and good sensitivity.

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 32 ◽  
Author(s):  
Zhezhe Wang ◽  
Xuechun Xiao ◽  
Tong Zou ◽  
Yue Yang ◽  
Xinxin Xing ◽  
...  

Citric acid capped CdS quantum dots (CA-CdS QDs), a new assembled fluorescent probe for copper ions (Cu2+), was synthesized successfully by a simple hydrothermal method. In this work, the fluorescence sensor for the detection of heavy and transition metal (HTM) ions has been extensively studied in aqueous solution. The results of the present study indicate that the obtained CA-CdS QDs could detect Cu2+ with high sensitivity and selectivity. It found that the existence of Cu2+ has a significant fluorescence quenching with a large red shifted (from greenish-yellow to yellowish-orange), but not in the presence of 17 other HTM ions. As a result, Cu2S, the energy level below the CdS conduction band, could be formed at the surface of the CA-CdS QDs and leads to the quenching of fluorescence of CA-CdS QDs. Under optimal conditions, the copper ions detection range using the synthesized fluorescence sensor was 1.0 × 10‒8 M to 5.0 × 10‒5 M and the limit of detection (LOD) is 9.2 × 10‒9 M. Besides, the as-synthesized CA-CdS QDs sensor exhibited good selectivity toward Cu2+ relative to other common metal ions. Thus, the CA-CdS QDs has potential applications for detecting Cu2+ in real water samples.


Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3126
Author(s):  
Rongzhen Li ◽  
Lian Li ◽  
Bin Wang ◽  
Liping Yu

The development of fluorescence sensing platforms with excellent photoluminescence capabilities is of great importance for their further application. In this work, a photonic crystal structure was successfully applied to enhance the luminescence performance of fluorescent hydrogel, and the application of the obtained hydrogel as a fluorescence sensor was explored. A polystyrene photonic crystal template was constructed via vertical deposition self-assembly; then, the precursor solution containing polyethylenimine-capped CdS quantum dots (PEI-CdS QDs) and monomers filled in the gap of the template. After the polymerization process, the desired hydrogel was obtained. PEI-CdS QDs endowed the hydrogel with its fluorescence property, while interestingly, the photonic crystal structure showed a significant enhancement effect on the fluorescence-emission capability. The mechanism of this phenomenon was revealed. Moreover, this hydrogel could be used as a reusable fluorescence sensor for the detection of nitrite in water with good selectivity. The limit of detection was determined to be 0.25 μmol/L, which is much lower than the maximum limit for nitrite in drinking water.


2011 ◽  
Vol 306-307 ◽  
pp. 1334-1337 ◽  
Author(s):  
Meng Zhang ◽  
Fu Wei Wan ◽  
Shen Guang Ge ◽  
Jing Hua Yu

We report the synthesis and characterization of a low-cost high-quality CdS quantum dots (QDs).The synthesis was performed in aqueous system. The aqueous CdS colloidal solution was prepared using thioglycollic acid as a capping agent. Zetasizer Nano ZS (Malvern, UK) was employed to characterize the partical size of CdS QDs. The UV-vis and photoluminescence (PL) spectra of samples were systematically characterized (the full width at half maximum was 38 nm). The maximum photoluminescence (PL) quantum yield (QY) was as high as 68.5 %. The fluorescence intensity was enhanced by copper (II). The relative fluorescence intensity was linear to copper (II) concentration over the range 4.0 ×10-6 - 2.8×10-5 g mL-1. The regression equation was ΔIF= 59.07+ 90.57c (c / μg mL-1). The highly monodispersed CdS QDs could be used in many fields.


2019 ◽  
Vol 14 (29) ◽  
pp. 169-174
Author(s):  
Zainab S. Sadeq

In this study, an easy, low-cost, green, and environmentallyfriendlier reagents have been used to prepare CdS QDs, in chemicalreaction method by mixed different ratio of CdO and sulfur inparaffin liquid as solvent and oleic acid as the reacting media indifferent concentration to get the optimum condition of the reactionto formation CdS QDs. The results give an indication that thebehavior is at small concentration of 4ml of the oleic acid is bestconcentration which give CdS QDs of small about to 9.23 nm withnano fiber configuration.


Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1165 ◽  
Author(s):  
Zhezhe Wang ◽  
Xuechun Xiao ◽  
Yue Yang ◽  
Tong Zou ◽  
Xinxin Xing ◽  
...  

A new high performance fluorescence assay for detection of Ag+ based on CdS quantum dots (QDs) using L-Aspartic acid (L-Asp) as a stabilizer was proposed in this work. The CdS quantum dots conjugation with L-Aspartic acid (L-Asp@CdS QDs) were successfully synthesized via a simple hydrothermal process. The QDs have a fluorescence emission band maximum at 595 nm with a quantum yield of 11%. The obtained CdS QDs exhibit a particle size of 1.63 ± 0.28 nm and look like quantum dot flowers. Basically, the fluorescence intensity of L-Asp@CdS QDs can be enhanced only upon addition of Ag+ and a redshift in the fluorescence spectrum was observed. Under optimum conditions, the fluorescence enhancement of L-Asp@CdS QDs appeared to exhibit a good linear relationship in between 100–7000 nM (R2 = 0.9945) with the Ag+ concentration, with a detection limit of 39 nM. The results indicated that the L-Asp@CdS QDs were well used in detection for Ag+ as fluorescence probe in aqueous solution with high sensitivity and selectivity. Moreover, the sensing system has been applied in detection Ag+ in real water samples. The recovery test results were 98.6%~113%, and relative standard deviation (n = 5) is less than 3.6%, which was satisfactory.


2016 ◽  
Vol 5 (7) ◽  
pp. 59-62 ◽  
Author(s):  
Reza Hoseinpour Kouhestany ◽  
Seyed Naser Azizi ◽  
Parmis Shakeri ◽  
Shaghyegh Rahmani

A new chemiluminescence (CL) method using cadmium sulfide quantum dots (QDs) as sensitizers is proposed for the chemiluminometric determination of cetirizine pharmaceutical formulation. CdS QDs were synthesized by using water soluble route. The nanoparticles were structurally and optically characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Ultra Violet-Visible (UV–Vis) absorption spectroscopy and scanning electron microscopy (SEM). In this study results shows that CdS quantum dots are enhancers of the weak CL emission. Trace amounts of cetirizine improved the sensitize effect of CdS quantum dots yielding a significant chemiluminescence enhancement of the Ce(IV)–SO32?–CdS QDs system. So, a new CL analysis system was selected for the determination of cetirizine. There is a good linear relationship between the relative chemiluminescence intensity and the concentration of cetirizine in the range of 1×10?9– 1×10?6 molL?1 with a correlation coefficient (R2) of 0.9963 at the optimum conditions. The limit of detection (LOD) of this system was found to be 5×10?11 M. This method is simple, sensitive and cost effective, and also is accommodating for pharmaceutical applications.Kouhestany et al., International Current Pharmaceutical Journal, June 2016, 5(7): 59-62


The Analyst ◽  
2021 ◽  
Author(s):  
Hui-Jun Zhang ◽  
Jin Zhu ◽  
Ning Bao ◽  
Shou-Nian Ding

The mechanism of enhanced ECL of MPA@CdS QDs by EDC activation was investigated, and a sandwich-type ECL immunosensor has been designed for Zika virus detection.


RSC Advances ◽  
2021 ◽  
Vol 11 (14) ◽  
pp. 7961-7971
Author(s):  
N. D. Vinh ◽  
P. M. Tan ◽  
P. V. Do ◽  
S. Bharti ◽  
V. X. Hoa ◽  
...  

The role of samarium (Sm) dopant on the structural, morphological, and optical properties of CdS QDs and CdS/ZnS core/shell QDs was methodically reported.


2013 ◽  
Vol 845 ◽  
pp. 441-445 ◽  
Author(s):  
Mustafa Arab ◽  
Noriah Bidin

In this project, laser induced breakdown spectroscopy (LIBS) has been utilized to determine the heavy element (Copper) in soil sample. LIBS was used in this work to measure the detection limit of Cu in soil sample, on the basis of spectral features, many parameters to improve the sensitivity of LIBS detection of copper are proposed. Q-switch Nd:YAG laser pulse was carried out at 90 mJ and wavelength of 1064 nm to excite the soil samples in purpose of produce a fluorescence emission (plasma), which were analyzed via spectrum analyzer. The important experimental conditions such as the energy of laser source, integration time, the distance and angle of optical fiber from the sparks were optimized for obtain a best LIBS signal. Calibration curve of the Cu peak found to be 236.81 nm as the best peak to calculate the limit of detection (LOD) and found in this study about 2 ppm. From the results the concentrations of Cu is realized to be lower than the allowance limits of 1500 ppm according to the United States Environmental Protection Agency USEPA.


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