Evidence for Multiple Trapping Mechanisms in Single CdSe/ZnS Quantum Dots from Fluorescence Intermittency Measurements over a Wide Range of Excitation Intensities

2011 ◽  
Vol 115 (14) ◽  
pp. 6341-6349 ◽  
Author(s):  
Amy A. Cordones ◽  
Teresa J. Bixby ◽  
Stephen R. Leone
Keyword(s):  
Quantum Dots ◽  
Multiple Trapping ◽  
Wide Range ◽  
Fluorescence Intermittency

scholarly journals Formation of Carbon Quantum Dots via Hydrothermal Carbonization: Investigate the Effect of Precursors

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 986
Author(s):  
Md Rifat Hasan ◽  
Nepu Saha ◽  
Thomas Quaid ◽  
M. Toufiq Reza
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Microcrystalline Cellulose ◽  
Uv Light ◽  
Synthesis Method ◽  
Hydrothermal Carbonization ◽  
Carbon Quantum Dots ◽  
Medical Diagnostics ◽  
Particle Size Range ◽  
Wide Range

Carbon quantum dots (CQDs) are nanomaterials with a particle size range of 2 to 10 nm. CQDs have a wide range of applications such as medical diagnostics, bio-imaging, biosensors, coatings, solar cells, and photocatalysis. Although the effect of various experimental parameters, such as the synthesis method, reaction time, etc., have been investigated, the effect of different feedstocks on CQDs has not been studied yet. In this study, CQDs were synthesized from hydroxymethylfurfural, furfural, and microcrystalline cellulose via hydrothermal carbonization at 220 °C for 30 min of residence time. The produced CQDs showed green luminescence behavior under the short-wavelength UV light. Furthermore, the optical properties of CQDs were investigated using ultraviolet-visible spectroscopy and emission spectrophotometer, while the morphology and chemical bonds of CQDs were investigated using transmission electron microscopy and Fourier-transform infrared spectroscopy, respectively. Results showed that all CQDs produced from various precursors have absorption and emission properties but these optical properties are highly dependent on the type of precursor. For instance, the mean particle sizes were 6.36 ± 0.54, 5.35 ± 0.56, and 3.94 ± 0.60 nm for the synthesized CQDs from microcrystalline cellulose, hydroxymethylfurfural, and furfural, respectively, which appeared to have similar trends in emission intensities. In addition, the synthesized CQDs experienced different functionality (e.g., C=O, O-H, C-O) resulting in different absorption behavior.

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.

Microplasma Band Structure Engineering in Graphene Quantum Dots for Sensitive and Wide-Range pH Sensing

2021 ◽  
Author(s):  
Darwin Kurniawan ◽  
Bai Amutha Anjali ◽  
Owen Setiawan ◽  
Kostya Ken Ostrikov ◽  
Yongchul G. Chung ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Band Structure ◽  
Graphene Quantum Dots ◽  
Ph Sensing ◽  
Wide Range ◽  
Structure Engineering

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 Carbon Based Nanodots in Early Diagnosis of Cancer

2021 ◽  
Vol 9 ◽  
Author(s):  
Gurpal Singh ◽  
Harinder Kaur ◽  
Akanksha Sharma ◽  
Joga Singh ◽  
Hema Kumari Alajangi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Early Stage ◽  
Imaging Techniques ◽  
Graphene Quantum Dots ◽  
Carbon Quantum Dots ◽  
Diagnostic Methods ◽  
Early Diagnosis Of Cancer ◽  
Successful Treatment Outcome ◽  
Wide Range ◽  
Carbon Based

Detection of cancer at an early stage is one of the principal factors associated with successful treatment outcome. However, current diagnostic methods are not capable of making sensitive and robust cancer diagnosis. Nanotechnology based products exhibit unique physical, optical and electrical properties that can be useful in diagnosis. These nanotech-enabled diagnostic representatives have proved to be generally more capable and consistent; as they selectively accumulated in the tumor site due to their miniscule size. This article rotates around the conventional imaging techniques, the use of carbon based nanodots viz Carbon Quantum Dots (CQDs), Graphene Quantum Dots (GQDs), Nanodiamonds, Fullerene, and Carbon Nanotubes that have been synthesized in recent years, along with the discovery of a wide range of biomarkers to identify cancer at early stage. Early detection of cancer using nanoconstructs is anticipated to be a distinct reality in the coming years.

Gold nanoparticle-graphene quantum dots nanozyme for the wide range and sensitive electrochemical determination of quercetin in plasma droplets

2020 ◽  
Vol 187 (11) ◽  
Author(s):  
Cristina Stefanov ◽  
Catalina Cioates Negut ◽  
Livia Alexandra Dinu Gugoasa ◽  
Jacobus (Koos) Frederick van Staden
Keyword(s):  
Quantum Dots ◽  
Gold Nanoparticle ◽  
Graphene Quantum Dots ◽  
Electrochemical Determination ◽  
Wide Range

scholarly journals Green Preparation of Fluorescent Carbon Quantum Dots from Cyanobacteria for Biological Imaging

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 616 ◽  
Author(s):  
Xi Wang ◽  
Pei Yang ◽  
Qian Feng ◽  
Taotao Meng ◽  
Jing Wei ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Carbon Source ◽  
Large Scale ◽  
Low Cost ◽  
Average Diameter ◽  
Carbon Quantum Dots ◽  
Water Soluble ◽  
High Concentration ◽  
Wide Range ◽  
Low Cytotoxicity

Biomass-based carbon quantum dots (CQDs) have become a significant carbon materials by their virtues of being cost-effective, easy to fabricate and low in environmental impact. However, there are few reports regarding using cyanobacteria as a carbon source for the synthesis of fluorescent CQDs. In this study, the low-cost biomass of cyanobacteria was used as the sole carbon source to synthesize water-soluble CQDs by a simple hydrothermal method. The synthesized CQDs were mono-dispersed with an average diameter of 2.48 nm and exhibited excitation-dependent emission performance with a quantum yield of 9.24%. Furthermore, the cyanobacteria-derived CQDs had almost no photobleaching under long-time UV irradiation, and exhibited high photostability in the solutions with a wide range of pH and salinity. Since no chemical reagent was involved in the synthesis of CQDs, the as-prepared CQDs were confirmed to have low cytotoxicity for PC12 cells even at a high concentration. Additionally, the CQDs could be efficiently taken up by cells to illuminate the whole cell and create a clear distinction between cytoplasm and nucleus. The combined advantages of green synthesis, cost-effectiveness and low cytotoxicity make synthesized CQDs a significant carbon source and broaden the application of cyanobacteria and provide an economical route to fabricate CQDs on a large scale.

scholarly journals Further Development of Near-Infrared Mediated Quantum Dots and Paclitaxel Co-loaded Nanostructured Lipid Carrier System for Cancer Theragnostic

2020 ◽  
Vol 19 ◽  
pp. 153303382091430
Author(s):  
Livesey D. Olerile
Keyword(s):  
Quantum Dots ◽  
Cancer Treatment ◽  
Hepg2 Cells ◽  
Near Infrared ◽  
Early Stage ◽  
Treatment Protocol ◽  
Nanostructured Lipid Carriers ◽  
Nanostructured Lipid Carrier ◽  
Wide Range ◽  
Mcf 7

Of colloidal systems, ceteris paribus, nanostructured lipid carriers are second to none in offering a single-unit platform for multifunctional benefits. Quantum dots are known to possess unique properties that make them ideal for imaging purpose and that they may be used for cancer detection. For several decades, paclitaxel has been the most effective drug against a wide range of solid tumours. Theragnostic nanomedicine provides a platform to monitor, evaluate, and individualize treatment in real time. Evaluation of cancer treatment outcome at an early stage therapy is key to increase survival prospects of a patient. Previously, a novel co-loaded nanostructured lipid carriers’ theragnostic system for parenteral administration was developed. The aim of this study was to further investigate the co-loaded nanostructured lipid carriers in order to provide interpretation necessary for preclinical elucidation of the formulation, in part. The co-loaded nanostructured lipid carriers were prepared by oil/water emulsification-solvent evaporation technique. In this study, stability and co-loaded nanostructured lipid carriers’ internalization by MCF 7 and HepG2 cells were investigated. The co-loaded nanostructured lipid carriers was stable at 4°C for 1 month. The formulation was successfully internalized by MCF-7 and HepG2 cells. Nevertheless, the co-loaded nanostructured lipid carrier was more apt for MCF-7 cells. This finding affirms the formulation to be the most appropriate for breast cancer treatment. In addition, if taken correctly by a patient for a month, the formulation would give true reflection of the contents’ amounts, the factor paramount to appropriate changes in treatment protocol. It can therefore safely be concluded that the co-loaded nanostructured lipid carrier formulation may be potentially an effective theragnostic translational system.

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