scholarly journals A Chemiluminescent Method for the Detection of H2O2 and Glucose Based on Intrinsic Peroxidase-Like Activity of WS2 Quantum Dots

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 689 ◽  
Author(s):  
Mahsa Haddad Irani-nezhad ◽  
Javad Hassanzadeh ◽  
Alireza Khataee ◽  
Yasin Orooji
Keyword(s):  
Quantum Dots ◽  
Limit Of Detection ◽  
Detection System ◽  
Electrochemical Techniques ◽  
Enzymatic Reaction ◽  
Fluorescence Emission ◽  
Excitation Wavelength ◽  
High Fluorescence ◽  
Peroxidase Enzymes ◽  
Mimetic Behavior

Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS2 quantum dots (WS2 QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS2 QDs with a size of 1–1.5 nm had a high fluorescence emission, dependent on the excitation wavelength. WS2 QDs with uniform morphology showed a high catalytic effect in destroying H2O2. The peroxidase-like activity of synthesized nanostructures was studied in H2O2 chemical and electrochemical reduction systems. The mimetic effect of WS2 QDs was also shown in an H2O2–rhodamine B (RB) chemiluminescence system. For this aim, a stopped-flow chemiluminescence (CL) detection system was applied. Also, in order to confirm the peroxidase-like effect of quantum dots, colorimetry and electrochemical techniques were used. In the enzymatic reaction of glucose, H2O2 is one of the products which can be determined. Under optimum conditions, H2O2 can be detected in the concentration range of 0–1000 nmol·L−1, with a detection limit of 2.4 nmol·L−1. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.01–30 nmol·L−1, with a limit of detection (3S) of 4.2 nmol·L−1.

scholarly journals A Compact Detection Platform Based on Gradient Guided-Mode Resonance for Colorimetric and Fluorescence Liquid Assay Detection

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2797
Author(s):  
Jing-Jhong Gao ◽  
Ching-Wei Chiu ◽  
Kuo-Hsing Wen ◽  
Cheng-Sheng Huang
Keyword(s):  
Limit Of Detection ◽  
Detection System ◽  
Fluorescence Emission ◽  
Assay Sensitivity ◽  
Detection Range ◽  
Current Form ◽  
Guided Mode ◽  
Spectral Detection ◽  
Guided Mode Resonance ◽  
Colorimetric Assays

This paper presents a compact spectral detection system for common fluorescent and colorimetric assays. This system includes a gradient grating period guided-mode resonance (GGP-GMR) filter and charge-coupled device. In its current form, the GGP-GMR filter, which has a size of less than 2.5 mm, can achieve a spectral detection range of 500–700 nm. Through the direct measurement of the fluorescence emission, the proposed system was demonstrated to detect both the peak wavelength and its corresponding intensity. One fluorescent assay (albumin) and two colorimetric assays (albumin and creatinine) were performed to demonstrate the practical application of the proposed system for quantifying common liquid assays. The results of our system exhibited suitable agreement with those of a commercial spectrometer in terms of the assay sensitivity and limit of detection (LOD). With the proposed system, the fluorescent albumin, colorimetric albumin, and colorimetric creatinine assays achieved LODs of 40.99 and 398 and 25.49 mg/L, respectively. For a wide selection of biomolecules in point-of-care applications, the spectral detection range achieved by the GGP-GMR filter can be further extended and the simple and compact optical path configuration can be integrated with a lab-on-a-chip system.

scholarly journals Handheld Enzymatic Luminescent Biosensor for Rapid Detection of Heavy Metals in Water Samples

Chemosensors ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 16 ◽  
Author(s):  
Kirill Lukyanenko ◽  
Ivan Denisov ◽  
Vladimir Sorokin ◽  
Anton Yakimov ◽  
Elena Esimbekova ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Rapid Detection ◽  
Limit Of Detection ◽  
Detection System ◽  
Test Procedure ◽  
Enzymatic Reaction ◽  
Water Quality Assessment ◽  
Micro Milling ◽  
Microfluidic Chips ◽  
Silicon Photomultiplier

Enzymatic luminescent systems are a promising tool for rapid detection of heavy metals ions for water quality assessment. Nevertheless, their widespread use is limited by the lack of test procedure automation and available sensitive handheld luminometers. Herein we describe integration of disposable microfluidic chips for bioluminescent enzyme-inhibition based assay with a handheld luminometer, which detection system is based on a thermally stabilized silicon photomultiplier (SiPM). Microfluidic chips were made of poly(methyl methacrylate) by micro-milling method and sealed using a solvent bonding technique. The composition of the bioluminescent system in microfluidic chip was optimized to achieve higher luminescence intensity and storage time. Results indicate that developed device provided comparable sensitivity with bench-scale PMT-based commercial luminometers. Limit of detection for copper (II) sulfate reached 2.5 mg/L for developed biosensor. Hereby we proved the concept of handheld enzymatic optical biosensors with disposable chips for bioassay. The proposed biosensor can be used as an early warning field-deployable system for rapid detection of heavy metals salts and other toxic chemicals, which affect bioluminescent signal of enzymatic reaction.

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

2021 ◽  
Author(s):  
Rahman Hallaj ◽  
Zahra Hosseinchi
Keyword(s):  
Quantum Dots ◽  
Glucose Oxidase ◽  
Limit Of Detection ◽  
Low Cost ◽  
Fluorescence Emission ◽  
Cds Quantum Dots ◽  
Fluorescence Sensing ◽  
Experimental Conditions ◽  
Glucose Determination ◽  
Cds Qds

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.

scholarly journals γ-Radiation Enhanced Luminescence of Thiol-Capped Quantum Dots in Aqueous Solution

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 506 ◽  
Author(s):  
Shuquan Chang ◽  
Xian Wu ◽  
Jianzhang Lan ◽  
Zheng Li ◽  
Xiaohong Zhang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Photoelectron Spectroscopy ◽  
Fluorescence Emission ◽  
High Energy ◽  
Γ Radiation ◽  
X Ray ◽  
Fluorescence Efficiency ◽  
High Fluorescence ◽  
Xrd Patterns

Quantum dots (QDs) have attracted great attention due to their unique optical properties. High fluorescence efficiency is very important for their practical application. In this study, we report a simple and efficient strategy to enhance the photoluminescence of water-dispersed thiol-capped QDs using γ-radiation. Three kinds of QDs with different surface ligands and cores (MPA-CdTe, MPA-CdSe and Cys-CdTe) were fabricated and irradiated by high-energy γ-ray in an aqueous solution. Their photoluminescence intensities were significantly enhanced after irradiation, which were closely related to the radiation dose and the structure of QDs. The positions of the fluorescence emission peaks did not shift obviously after irradiation. The mechanism of photoluminescence enhancement was discussed based on the results of photoluminescence (PL) spectra, UV-visible light absorption (UV-vis) spectra, transmission electron microscope (TEM), X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS). This method can be employed to uniformly treat large batches of QDs at room temperature and without other chemicals.

scholarly journals Levofloxacin Detection Using l-Cysteine Capped MgS Quantum Dots via the Photoinduced Electron Transfer Process

2021 ◽  
Vol 3 ◽  
Author(s):  
S. Z. H. Hashmi ◽  
Tarun Kumar Dhiman ◽  
Navneet Chaudhary ◽  
Avinash Kumar Singh ◽  
Rahul Kumar ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Electron Transfer ◽  
Limit Of Detection ◽  
Underlying Mechanism ◽  
Microscopy Study ◽  
Antibiotics Resistance ◽  
Excitation Wavelength ◽  
Human Beings ◽  
Interaction Study ◽  
Free System

Antibiotics resistance is becoming one of the biggest problems of the 21st century. The prior detection of antibiotics resistance can help human beings in better treatment of diseases. Here, we have used l-Cysteine capped magnesium sulfide quantum dots (L-Cyst-MgS QDs) to detect Levofloxacin antibiotic. L-Cyst-MgS QDs were synthesized using the hydrothermal method. Transmission electron microscopy study showed monodispersed L-Cyst-MgS QDs of 2–4 nm in size. Energy dispersive x-ray photoemission spectroscopy study confirmed the elemental composition of the L-Cyst-MgS QDs without any impurity. UV-vis absorption study showed a peak centered around 340 nm. The photoluminescence study exhibited the maximum peak at 410 nm for 340 nm of excitation wavelength. L-Cyst-MgS QDs were studied with thirteen antibiotics, namely Thiamphenicol, Gentamicin, Erythromycin, Ofloxacin, Ampicillin, Ciprofloxacin, Tetracycline, Chloramphenicol, Florfenicol, Amoxicillin, Moxifloxacin, Norfloxacin, and Levofloxacin. Among these, Levofloxacin showed the most significant change in the peaks’ intensity and was further used for the interaction study. In the interaction study, the peak corresponding to MgS showed a continuous decrease, while the peak corresponding to Levofloxacin showed an increase with the increased concentrations (0–100 μg/ml) of Levofloxacin. Linear behavior was obtained in the range of 1–90 μg/ml. FT-IR study confirmed the interaction of the Levofloxacin with L-Cyst-MgS QDs. The Time-resolved fluorescence spectroscopy showed identical lifetime for both the samples and no spectral overlap confirm the FRET free system. The underlying mechanism is explained based on the electron transfer from the conduction band of the L-Cyst-MgS QDs to the HOMO of Levofloxacin. The limit of detection was found to be 0.21 μg/ml.

scholarly journals Synthesis and Optical Characterizations of the Fluorescence Silica Nanoparticles Containing Quantum Dots

2020 ◽  
Vol 36 (2) ◽  
Author(s):  
Chu Viet Ha ◽  
Chu Anh Tuan ◽  
Nguyen Thi Bich Ngoc ◽  
Tran Hong Nhung ◽  
Nguyen Quang Liem ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Silica Nanoparticles ◽  
Water Solubility ◽  
Fluorescence Emission ◽  
Ammonium Hydroxide ◽  
Sio2 Nanoparticles ◽  
Synthesis Conditions ◽  
High Fluorescence ◽  
Modified Stöber Method ◽  
Fluorescence Material

The quantum dots coated by silica  is fluorescence material class with great biocompatibility, low toxicity and water-solubility, that is suitable for bioapplications. This work presents the synthesis of SiO2 coated CdTe/ZnSe (named CdTe) quantum dots (CdTe@SiO2 nanoparticles) via a wet chemmical route called modified Stöber method. The compounds tetraethylorthosilicate (TEOS) has used as precursors, aminopropyltriethoxysilane (APTES) is  as  electric neutralizer, and ammonium hydroxide is used as catalysts. The size of CdTe@SiO2 nanoparticles was estimated about 70 to 150 nm depending on the quantities of H2O, APTEOS, and catalysts. The emission behaviours of SiO2 coated quantum dots was effected by ratio of substances participating in the reaction and synthesis conditions. with the ratio (by volume) of suitable substances: TEOS:solution of QDs:NH4OH:APTES:H2O being 1.5:1.5x10-2:0.8x10-2:4x10-2:3x10-4:5x10-2, the prepared silica nanoparticles containing quantum dots show high fluorescence emission efficiency, the fluorescence intensity is higher than that of uncoated CdTe/ZnSe quantum dots. This is a positive result in the technique of manufacturing luminescent silica nanoparticles containing quantum dots. The results show an ability to use the CdTe@SiO2 nanoparticles for biological application.

scholarly journals Optofluidic Formaldehyde Sensing: Towards On-Chip Integration

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 673 ◽  
Author(s):  
Daniel Mariuta ◽  
Arumugam Govindaraji ◽  
Stéphane Colin ◽  
Christine Barrot ◽  
Stéphane Le Calvé ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Detection System ◽  
Fluorescence Emission ◽  
Complementary Metal Oxide Semiconductor ◽  
Image Sensor ◽  
Air Pollutant ◽  
Oxide Semiconductor ◽  
Excitation Wavelength ◽  
Formaldehyde Concentration ◽  
On Chip

Formaldehyde (HCHO), a chemical compound used in the fabrication process of a broad range of household products, is present indoors as an airborne pollutant due to its high volatility caused by its low boiling point ( T = − 19 °C). Miniaturization of analytical systems towards palm-held devices has the potential to provide more efficient and more sensitive tools for real-time monitoring of this hazardous air pollutant. This work presents the initial steps and results of the prototyping process towards on-chip integration of HCHO sensing, based on the Hantzsch reaction coupled to the fluorescence optical sensing methodology. This challenge was divided into two individually addressed problems: (1) efficient airborne HCHO trapping into a microfluidic context and (2) 3,5–diacetyl-1,4-dihydrolutidine (DDL) molecular sensing in low interrogation volumes. Part (2) was addressed in this paper by proposing, fabricating, and testing a fluorescence detection system based on an ultra-low light Complementary metal-oxide-semiconductor (CMOS) image sensor. Two three-layer fluidic cell configurations (quartz–SU-8–quartz and silicon–SU-8–quartz) were tested, with both possessing a 3.5 µL interrogation volume. Finally, the CMOS-based fluorescence system proved the capability to detect an initial 10 µg/L formaldehyde concentration fully derivatized into DDL for both the quartz and silicon fluidic cells, but with a higher signal-to-noise ratio (SNR) for the silicon fluidic cell ( S N R s i l i c o n = 6.1 ) when compared to the quartz fluidic cell ( S N R q u a r t z = 4.9 ). The signal intensity enhancement in the silicon fluidic cell was mainly due to the silicon absorption coefficient at the excitation wavelength,   a ( λ a b s = 420   nm ) = 5 × 10 4   cm − 1 , which is approximately five times higher than the absorption coefficient at the fluorescence emission wavelength, a ( λ e m = 515   nm ) = 9.25 × 10 3   cm − 1 .

scholarly journals One-Pot Hydrothermal Synthesis of Carbon Dots as Fluorescent Probes for the Determination of Mercuric and Hypochlorite Ions

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1831
Author(s):  
Hsin Lee ◽  
Yen-Chang Su ◽  
Hsiang-Hao Tang ◽  
Yu-Sheng Lee ◽  
Jan-Yee Lee ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Fluorescent Probes ◽  
Carbon Dots ◽  
Limit Of Detection ◽  
Tap Water ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Excitation Wavelength ◽  
One Pot ◽  
Fluorescence Emission Spectra

Nitrogen and sulfur codoped carbon dots (NSCDs) were synthesized via a one-pot hydrothermal method, and citric acid, ethylenediamine, and methyl blue were used as precursors. The obtained NSCDs were spherical with an average size of 1.86 nm. The fluorescence emission spectra of the NSCDs were excitation independent and emitted blue fluorescence at 440 nm with an excitation wavelength at 350 nm. The quantum yield of the NSCDs was calculated to be 68.0%. The NSCDs could be constructed as fluorescent probes for highly selective and sensitive sensing mercuric (Hg2+) and hypochlorite (ClO−) ions. As the addition of Hg2+ or ClO− ions to the NSCDs, the fluorescence intensity was effectively quenched due to dynamic quenching. Under the optimal conditions, the linear response of the fluorescence intensity ranged from 0.7 μM to 15 μM with a detection limit of 0.54 μM and from 0.3 μM to 5.0 μM with a limit of detection of 0.29 μM for Hg2+ and ClO− ions, respectively. Finally, the proposed method was successfully used for quantifying Hg2+ and ClO− ions in spiked tap water samples.

scholarly journals [5]Helicene-Scaffold Fluorescence Sensing for Selective Detection of Au3+ Ions and Gold Nanoparticle

2021 ◽  
Author(s):  
Pichayanun Sinthuprasert ◽  
Anuwut Petdum ◽  
Pattanawit Swanglap ◽  
Waraporn Panchan ◽  
Thanasat Sooksimuang ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Photophysical Properties ◽  
Stokes Shift ◽  
Fluorescence Emission ◽  
Fluorescence Sensing ◽  
High Productivity ◽  
Real Water Samples ◽  
Detection Response ◽  
High Fluorescence ◽  
Anhydride Derivative

A new quenching fluorescence sensor (MDP) with high productivity was easily synthesized from a [5]helicene anhydride derivative and propargyl bromide. This MDP sensor has significant photophysical properties, including high fluorescence emission and a large Stokes shift, and it exhibits selectivity and an excellent detection response in distinguishing Au3+ ions from interfering metal ions in aqueous solution. The limit of detection of the sensor were determined to be 0.16 µmol L-1 or 32.0 ppb. Stoichiometric binding between the MDP and Au3+ ions was found to occur at a 1:2 ratio. Additionally, the MDP sensor shows an ability to detect gold ions in real water samples and recognize gold nanoparticles (AuNPs), which invites its further application in biological and environmental systems.

scholarly journals A Fluorescence System Composed of Nitrogen-doped Graphene Quantum Dots and Gold Nanoparticles Coated With Phenylalanine for Selective and Sensitive Quantification of Piroxicam in Biological Samples

2022 ◽  
Author(s):  
Maryam Moallemi Bahmani ◽  
Ali Mohammad Haji Shabani ◽  
Shayessteh Dadfarnia ◽  
Roya Afsharipour
Keyword(s):  
Quantum Dots ◽  
Gold Nanoparticles ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Fluorescence Emission ◽  
Calibration Graph ◽  
Serum Samples ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Abstract In this study, a sensitive fluorimetric method is proposed for the determination of piroxicam using nitrogen graphene quantum dots (N-GQDs) and gold nanoparticles coated with phenylalanine. The fluorescence emission of N-GQDs at 440 nm decreases with the increase of gold nanoparticles coated with phenylalanine. However, the addition of piroxicam causes the release of gold nanoparticles from the surface of quantum dots followed by the retrieval of the fluorescence emission of N-GQDs. Under the optimum conditions, the calibration graph was linear in the concentration range of 2.0-35.0 nmol L-1 for piroxicam with a limit of detection of 0.11 nmol L-1. The developed method was successfully applied for the determination of piroxicam in urine and serum samples.

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