scholarly journals A Highly Sensitive and Selective Fluorescent Probe Using MPA-InP/ZnS QDs for Detection of Trace Amounts of Cu2+ in Water

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2777
Author(s):  
Zeyu Xu ◽  
Yizhong Wang ◽  
Jiaran Zhang ◽  
Ce Shi ◽  
Xinting Yang
Keyword(s):  
Quantum Dots ◽  
Fluorescence Quenching ◽  
Fluorescence Intensity ◽  
Human Body ◽  
Fluorescence Probe ◽  
Limit Of Detection ◽  
Quenching Mechanism ◽  
Real Water Samples ◽  
Highly Sensitive ◽  
Fluorescence Quenching Mechanism

Detection of copper (II) ions (Cu2+) in water is important for preventing them from entering the human body to preserve human health. Here, a highly sensitive and selective fluorescence probe that uses mercaptopropionic acid (MPA)-capped InP/ZnS quantum dots (MPA-InP/ZnS QDs) was proposed for the detection of trace amounts of Cu2+ in water. The fluorescence of MPA-InP/ZnS QDs can be quenched significantly in the presence of Cu2+, and the fluorescence intensity shows excellent linearity when the concentration of Cu2+ varies from 0–1000 nM; this probe also exhibits an extremely low limit of detection of 0.22 nM. Furthermore, a possible fluorescence-quenching mechanism was proposed. The MPA-InP/ZnS QDs probes were further applied to the detection of trace Cu2+ in real water samples and drink samples, showing good feasibility.

Fabrication of a Dopamine Sensor Based on Carboxyl Quantum Dots

2015 ◽  
Vol 15 (10) ◽  
pp. 7871-7875 ◽  
Author(s):  
Fei Zhao ◽  
Jongsung Kim
Keyword(s):  
Quantum Dots ◽  
Energy Transfer ◽  
Fluorescence Quenching ◽  
Fluorescence Intensity ◽  
Limit Of Detection ◽  
Simple Procedure ◽  
Electronic Energy ◽  
Solution Ph ◽  
Electronic Energy Transfer

A quantum dot (QD)-based optical biosensor was developed to detect the activity of dopamine (DA) via the quenching of QD fluorescence intensity. In this study, we examined the fluorescence quenching of DA-conjugated quantum dots (DA@QDs) at various solution pH values. The fluorescence intensity of the QDs is quenched by electronic energy transfer from the QDs to the o-quinone group of dopamine oxide. The degree of fluorescence quenching was dependent on DA concentration. The influence of the external environment pH factor on fluorescence quenching was investigated. The results showed that the degree of fluorescence quenching of DA@QDs was highest in a slightly alkaline solution-pH of approximately 9. Fluorescence enhancement with increased pH appears to be due to electronic energy transfer, which is related to an increased degree of dopamine-o-quinone oxidation. The fluorescence quenching of QDs by DA is of considerable interest due to its potential for the direct detection of the DA in vivo via a simple procedure with a very low limit of detection.

Detection of Glucose in Human Serum Based on Silicon Dot Probe

2020 ◽  
Vol 16 (6) ◽  
pp. 744-752
Author(s):  
Kuan Luo ◽  
Xinyu Jiang
Keyword(s):  
Quantum Dots ◽  
Blood Glucose ◽  
Human Serum ◽  
Organic Dyes ◽  
Limit Of Detection ◽  
Fasting Blood Glucose ◽  
Glucose Biosensor ◽  
Metal Nanoclusters ◽  
Glucose Levels ◽  
Highly Sensitive

Background: Diabetes Mellitus (DM) is a major public metabolic disease that influences 366 million people in the world in 2011, and this number is predicted to rise to 552 million in 2030. DM is clinically diagnosed by a fasting blood glucose that is equal or greater than 7 mM. Therefore, the development of effective glucose biosensor has attracted extensive attention worldwide. Fluorescence- based strategies have sparked tremendous interest due to their rapid response, facile operation, and excellent sensitivity. Many fluorescent compounds have been employed for precise analysis of glucose, including quantum dots, noble metal nanoclusters, up-converting nanoparticles, organic dyes, and composite fluorescent microspheres. Silicon dot as promising quantum dots materials have received extensive attention, owing to their distinct advantages such as biocompatibility, low toxicity and high photostability. Methods: MnO2 nanosheets on the Si nanoparticles (NPs) surface serve as a quencher. Si NPs fluorescence can make a recovery by the addition of H2O2, which can reduce MnO2 to Mn2+, and the glucose can thus be monitored based on the enzymatic conversion of glucose by glucose oxidase to generate H2O2. Therefore, the glucose concentration can be derived by recording the fluorescence recovery spectra of the Si NPs. Results: This probe enabled selective detection of glucose with a linear range of 1-100 μg/mL and a limit of detection of 0.98 μg/mL. Compared with the commercial glucometer, this method showed favorable results and convincing reliability. Conclusion: We have developed a novel method based on MnO2 -nanosheet-modified Si NPs for rapid monitoring of blood glucose levels. By combining the highly sensitive H2O2/MnO2 reaction with the excellent photostability of Si NPs, a highly sensitive, selective, and cost-efficient sensing approach for glucose detection has been designed and applied to monitor glucose levels in human serum with satisfactory results.

scholarly journals Multi-Quantum Dots-Embedded Silica-Encapsulated Nanoparticle-Based Lateral Flow Assay for Highly Sensitive Exosome Detection

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 768
Author(s):  
Hyung-Mo Kim ◽  
Chiwoo Oh ◽  
Jaehyun An ◽  
Seungki Baek ◽  
Sungje Bock ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Limit Of Detection ◽  
Specific Binding ◽  
Calf Serum ◽  
Lateral Flow ◽  
Lateral Flow Immunoassay ◽  
Uniform Size ◽  
Highly Sensitive ◽  
Wide Range ◽  
New Biomarkers

Exosomes are attracting attention as new biomarkers for monitoring the diagnosis and prognosis of certain diseases. Colorimetric-based lateral-flow assays have been previously used to detect exosomes, but these have the disadvantage of a high limit of detection. Here, we introduce a new technique to improve exosome detection. In our approach, highly bright multi-quantum dots embedded in silica-encapsulated nanoparticles (M–QD–SNs), which have uniform size and are brighter than single quantum dots, were applied to the lateral flow immunoassay method to sensitively detect exosomes. Anti-CD63 antibodies were introduced on the surface of the M–QD–SNs, and a lateral flow immunoassay with the M–QD–SNs was conducted to detect human foreskin fibroblast (HFF) exosomes. Exosome samples included a wide range of concentrations from 100 to 1000 exosomes/µL, and the detection limit of our newly designed system was 117.94 exosome/μL, which was 11 times lower than the previously reported limits. Additionally, exosomes were selectively detected relative to the negative controls, liposomes, and newborn calf serum, confirming that this method prevented non-specific binding. Thus, our study demonstrates that highly sensitive and quantitative exosome detection can be conducted quickly and accurately by using lateral immunochromatographic analysis with M–QD–SNs.

A Unified Fluorescence Quenching Mechanism of Tetrazine-Based Dyes: Energy Transfer to a Dark State

2021 ◽  
Author(s):  
Weijie Chi ◽  
Lu Huang ◽  
Chao Wang ◽  
Davin Tan ◽  
Zhaochao Xu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Fluorescence Quenching ◽  
Quenching Mechanism ◽  
Dark State ◽  
Medical Diagnostic ◽  
Fluorogenic Probes ◽  
Fluorescence Quenching Mechanism ◽  
Diagnostic Applications

Tetrazine-based fluorogenic probes are powerful tools for bioimaging, biosensing, and medical diagnostic applications. In these probes, the attachment of a tetrazine moiety generates a non-fluorescent precursor; upon the bio-orthogonal reaction...

scholarly journals Synthesis and Properties of Nitrogen-Doped Carbon Quantum Dots Using Lactic Acid as Carbon Source

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 466
Author(s):  
Kaixin Chang ◽  
Qianjin Zhu ◽  
Liyan Qi ◽  
Mingwei Guo ◽  
Woming Gao ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Lactic Acid ◽  
Fluorescence Quenching ◽  
Functional Groups ◽  
Fluorescence Intensity ◽  
Carbon Quantum Dots ◽  
Nitrogen Doped ◽  
Ph Values ◽  
Wide Range ◽  
Nitrogen Doped Carbon

Nitrogen-doped carbon quantum dots (N-CQDs) were synthesized in a one-step hydrothermal technique utilizing L-lactic acid as that of the source of carbon and ethylenediamine as that of the source of nitrogen, and were characterized using dynamic light scattering, X-ray photoelectron spectroscopy ultraviolet-visible spectrum, Fourier-transformed infrared spectrum, high-resolution transmission electron microscopy, and fluorescence spectrum. The generated N-CQDs have a spherical structure and overall diameters ranging from 1–4 nm, and their surface comprises specific functional groups such as amino, carboxyl, and hydroxyl, resulting in greater water solubility and fluorescence. The quantum yield of N-CQDs (being 46%) is significantly higher than that of the CQDs synthesized from other biomass in literatures. Its fluorescence intensity is dependent on the excitation wavelength, and N-CQDs release blue light at 365 nm under ultraviolet light. The pH values may impact the protonation of N-CQDs surface functional groups and lead to significant fluorescence quenching of N-CQDs. Therefore, the fluorescence intensity of N-CQDs is the highest at pH 7.0, but it decreases with pH as pH values being either more than or less than pH 7.0. The N-CQDs exhibit high sensitivity to Fe3+ ions, for Fe3+ ions would decrease the fluorescence intensity of N-CQDs by 99.6%, and the influence of Fe3+ ions on N-CQDs fluorescence quenching is slightly affected by other metal ions. Moreover, the fluorescence quenching efficiency of Fe3+ ions displays an obvious linear relationship to Fe3+ concentrations in a wide range of concentrations (up to 200 µM) and with a detection limit of 1.89 µM. Therefore, the generated N-CQDs may be utilized as a robust fluorescence sensor for detecting pH and Fe3+ ions.

scholarly journals “Switch-Off-On” Detection of Fe3+ and F− Ions Based on Fluorescence Silicon Nanoparticles and Their Application to Food Samples

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 213
Author(s):  
Hongli Ye ◽  
Lukai Zhao ◽  
Xinghui Ren ◽  
Youqiong Cai ◽  
Hai Chi
Keyword(s):  
Silicon Nanoparticles ◽  
Antarctic Krill ◽  
Fluorescence Probe ◽  
Tap Water ◽  
Food Samples ◽  
Fluorescence Recovery ◽  
Quenching Mechanism ◽  
Zeta Potentials ◽  
Visible Spectra ◽  
Fluorescence Quenching Mechanism

An approach to the detection of F− ions in food samples was developed based on a “switch-off-on” fluorescence probe of silicon nanoparticles (SiNPs). The fluorescence of the synthetic SiNPs was gradually quenched in the presence of Fe3+ ion and slightly recovered with the addition of F− ion owing to the formation of a stable and colorless ferric fluoride. The fluorescence recovery exhibited a good linear relationship (R2 = 0.9992) as the concentration of F− ion increased from 0 to 100 μmol·L−1. The detection limit of the established method of F− ion was 0.05 μmol·L−1. The recovery experiments confirmed the accuracy and reliability of the proposed method. The ultraviolet–visible spectra, fluorescence decays, and zeta potentials evidenced the fluorescence quenching mechanism involving the electron transfer between the SiNPs and Fe3+ ion, while the fluorescence recovery resulted from the formation of ferric fluoride. Finally, SiNPs were successfully applied to detect F− ions in tap water, Antarctic krill, and Antarctic krill powder.

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