scholarly journals Fluorescence Quenching of Quantum Dots by DNA Nucleotides and Amino Acids

2011 ◽  
Vol 64 (5) ◽  
pp. 512 ◽  
Author(s):  
Daniel Siegberg ◽  
Dirk-Peter Herten
Keyword(s):  
Amino Acids ◽  
Quantum Dots ◽  
Fluorescence Quenching ◽  
Single Molecule ◽  
Fluorescence Emission ◽  
Single Particle Tracking ◽  
Quenching Mechanism ◽  
Widespread Application ◽  
Biochemical Compounds ◽  
Single Molecule Fluorescence Spectroscopy

Quantum dots found widespread application in the biosciences as bright and highly photo-stable fluorescent probes, i.e. for single-particle tracking. In this work we used ensemble spectroscopy and single-molecule techniques to study the quenching of quantum dots by various biochemical compounds that are usually present in living cells and might thus influence the experiments. We found not only nucleotides such as cytosine, guanine, and thymine can significantly influence the fluorescence emission of CdSe and CdTe quantum dots, but also amino acids, like asparagine and tryptophan. Bulk studies on fluorescence quenching indicated a static quenching mechanism. Interestingly, we could also show by single-molecule fluorescence spectroscopy that quenching of the quantum dots can be irreversible, suggesting either a redox-reaction between quantum dot and quencher or strong binding of the quencher to the surface of the bio-conjugated quantum dots.

scholarly journals Real-Time 3D Single Particle Tracking: Towards Active Feedback Single Molecule Spectroscopy in Live Cells

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2826 ◽  
Author(s):  
Shangguo Hou ◽  
Courtney Johnson ◽  
Kevin Welsher
Keyword(s):  
Fluorescence Spectroscopy ◽  
Real Time ◽  
Temporal Resolution ◽  
Single Molecule ◽  
Particle Tracking ◽  
Single Particle ◽  
Single Particle Tracking ◽  
Single Molecule Fluorescence ◽  
Single Molecule Fluorescence Spectroscopy ◽  
Active Feedback

Single molecule fluorescence spectroscopy has been largely implemented using methods which require tethering of molecules to a substrate in order to make high temporal resolution measurements. However, the act of tethering a molecule requires that the molecule be removed from its environment. This is especially perturbative when measuring biomolecules such as enzymes, which may rely on the non-equilibrium and crowded cellular environment for normal function. A method which may be able to un-tether single molecule fluorescence spectroscopy is real-time 3D single particle tracking (RT-3D-SPT). RT-3D-SPT uses active feedback to effectively lock-on to freely diffusing particles so they can be measured continuously with up to photon-limited temporal resolution over large axial ranges. This review gives an overview of the various active feedback 3D single particle tracking methods, highlighting specialized detection and excitation schemes which enable high-speed real-time tracking. Furthermore, the combination of these active feedback methods with simultaneous live-cell imaging is discussed. Finally, the successes in real-time 3D single molecule tracking (RT-3D-SMT) thus far and the roadmap going forward for this promising family of techniques are discussed.

Doping effect and fluorescence quenching mechanism of N-doped graphene quantum dots in the detection of dopamine

Talanta ◽  
2019 ◽  
Vol 196 ◽  
pp. 563-571 ◽  
Author(s):  
Y. Ma ◽  
A.Y. Chen ◽  
X.F. Xie ◽  
X.Y. Wang ◽  
D. Wang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Fluorescence Quenching ◽  
Graphene Quantum Dots ◽  
Doping Effect ◽  
Quenching Mechanism ◽  
Doped Graphene ◽  
Fluorescence Quenching Mechanism

Aggregation of zinc tetraphenylporphyrin characterized by ensemble and single-molecule fluorescence spectroscopy

2011 ◽  
Vol 89 (2) ◽  
pp. 122-129 ◽  
Author(s):  
Jaclyn A. O’Brien ◽  
Yin Lu ◽  
Emma N. Hooley ◽  
Kenneth P. Ghiggino ◽  
Ronald P. Steer ◽  
...  
Keyword(s):  
Single Molecule ◽  
Fluorescence Emission ◽  
Blue Shift ◽  
Water Soluble ◽  
Annihilation Process ◽  
Single Molecule Fluorescence ◽  
Low Concentrations ◽  
Single Molecule Fluorescence Spectroscopy ◽  
Potential Applications ◽  
Significant Blue Shift

The aggregation of metalloporphyrins is believed to play a crucial role in the excited-state annihilation process known as triplet–triplet annihilation, which in turn has significant potential applications in photon upconversion schemes. In this work, the propensity of the water-soluble metalloporphyrin zinc (II) meso-tetra(4-sulfonatophenyl)porphine to undergo aggregation when adsorbed to glass cover slips was investigated by single-molecule fluorescence microscopy. In proof-of-principle experiments, it was demonstrated (1) that individual molecules of the metalloporphyrin can be directly visualized in spite of their very weak fluorescence emission, and (2) that at low concentrations (10−8 mol/L), the molecule has a strong tendency to form multimolecular aggregates. A subset of the multimolecular aggregates shows a significant blue-shift in fluorescence emission, though at present the precise nature of the molecular aggregates remains unclear.

scholarly journals Distance dependence of near-field fluorescence enhancement and quenching of single quantum dots

2011 ◽  
Vol 2 ◽  
pp. 645-652 ◽  
Author(s):  
Volker Walhorn ◽  
Jan Paskarbeit ◽  
Heinrich Gotthard Frey ◽  
Alexander Harder ◽  
Dario Anselmetti
Keyword(s):  
Quantum Dots ◽  
Fluorescence Microscopy ◽  
Single Molecule ◽  
Dipolar Coupling ◽  
Near Field ◽  
Fluorescence Emission ◽  
Field Enhancement ◽  
Single Quantum ◽  
Distance Dependence ◽  
Single Quantum Dots

In fluorescence microscopy and spectroscopy, energy transfer processes between single fluorophores and fluorophore quencher pairs play an important role in the investigation of molecular distances or orientations. At distances larger than about 3 nm these effects originate predominantly from dipolar coupling. As these experiments are commonly performed in homogenous media, effects at the interface boundaries can be neglected. Nevertheless, the combination of such assays with single-molecule manipulation techniques such as atomic force microscopy (AFM) requires a detailed understanding of the influence of interfaces on dipolar coupling effects. In the presented work we used a combined total internal reflection fluorescence microscopy (TIRFM)–AFM setup to elucidate this issue. We measured the fluorescence emission emanating from single quantum dots as a function of distance from the apex of a gold-coated cantilever tip. As well as fluorescence quenching at close proximity to the tip, we found a nonlinear and nonmonotonic distance dependence of the fluorescence emission. To confirm and interpret our findings we performed calculations on the basis of a simplified multiple multipole (MMP) approach, which successfully supports our experimental data. Moreover, we revealed and quantified the influence of interfering processes such as field enhancement confined at interface boundaries, mirror dipoles and (resonant) dipolar coupling.

scholarly journals Exploring the fluorescence quenching interaction of amino acids and protein with natural organic matter by multi-spectroscopic method

2021 ◽  
Author(s):  
Kornravee Saipetch ◽  
Rajendra Khanal ◽  
Masaki Yamazaki ◽  
Qing-Long Fu ◽  
Chihiro Yoshimura ◽  
...  
Keyword(s):  
Amino Acids ◽  
Organic Matter ◽  
Hydrogen Bonding ◽  
Fluorescence Quenching ◽  
Natural Organic Matter ◽  
Spectroscopic Method ◽  
Quenching Mechanism ◽  
Potential Binding ◽  
Fluorescence Quenching Mechanism ◽  
Two Peaks

Abstract The main objective of this research was to explore the fluorescence quenching mechanism of humic substance (Suwannee River natural organic matter, (SWNOM)) to amino acids (tryptophan, tyrosine) and protein (bovine serum albumin, (BSA)) by multi-spectroscopic methods. The locations of the peak of tryptophan, tyrosine, and BSA from the Parallel Factor Analysis were at Ex/Em 280/356 nm, 275/302 nm, and 280/344 nm, respectively. For SWNOM, two peaks appeared at Ex/Em of 240/448 nm, and 350/450 nm. Static quenching was the dominant quenching mechanism between BSA and SWNOM, whereas, no quenching was observed between tryptophan or tyrosine and SWNOM. Fourier-transform infrared spectroscopy and thermodynamic calculation demonstrated that hydrogen bonding and van der Waals force are the potential binding forces of BSA-SWNOM complex, as a result of rearrangement in the secondary polypeptide carbonyl hydrogen bonding network of BSA. This rearrangement led to the conformational change in BSA that induced quenching of BSA fluorescence by SWNOM.

scholarly journals Highly sensitive detection of dengue biomarker using streptavidin-conjugated quantum dots

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Linh Tran ◽  
Sangkwon Park
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Fluorescence Quenching ◽  
Field Emission ◽  
Early Stage ◽  
Dengue Infection ◽  
Phosphate Buffer Solution ◽  
Fluorescence Emission ◽  
Structural Protein ◽  
Highly Sensitive

AbstractA highly sensitive immunosensor using streptavidin-conjugated quantum dots (QDs/SA) was developed to detect dengue biomarker of non-structural protein 1 (NS1) at very low concentration, so that it can probe dengue infection even in the early stage. The QDs/SA were first bound to biotinylated NS1 antibody (Ab) and the QDs/SA-Ab conjugates were then used to detect the NS1 antigen (Ag) in the Ag concentration range of 1 pM to 120 nM. The formation of QDs/SA-Ab and QDs/SA-Ab-Ag conjugates was confirmed by the measurements of field emission scanning electron microscopy (FF-SEM), field emission transmission electron microscopy (FE-TEM), dynamic light scattering (DLS), and zeta-potential. Fluorescence emission spectra of QDs/SA-Ab-Ag conjugates showed that the magnitude of fluorescence quenching was linearly proportional to the NS1 Ag concentration and it nicely followed the Stern–Volmer (SV) equation in phosphate buffer solution. However, in human plasma serum solution, the fluorescence quenching behavior was negatively deviated from the SV equation presumably due to interference by the serum component biomolecules, and it was well explained by the Lehrer equation. These results suggest that the current approach is promising because it is highly sensitive, fast, simple, and convenient, and thus it has a potential of application for point-of-care.

Modification of Blinking Statistics in Solid State Quantum Dot/Conjugated Organic Polymer Composite Nanostructures

2006 ◽  
Vol 959 ◽  
Author(s):  
Nathan I Hammer ◽  
Kevin T Early ◽  
Michael Y Odoi ◽  
Ravisubhash Tangirala ◽  
Kevin Sill ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Solid State ◽  
Quantum Dot ◽  
Single Molecule ◽  
Fluorescence Emission ◽  
Phase Segregation ◽  
Organic Polymer ◽  
Cdse Quantum Dots ◽  
The Stability ◽  
Fluorescence Intermittency

ABSTRACTFluorescence intermittency, or “blinking” in quantum dot systems has been the subject of great interest since the first observation of this phenomenon nearly 10 years ago. The stability of quantum dot fluorescence emission is especially important in the context of photovoltaic, optoelectronic, and biological applications, where device performance, or the ability to track labeled particles, is affected adversely by fluorescence intermittency. Single-molecule spectroscopy combined with atomic force microscopy measurements reveal that CdSe quantum dots functionalized with oligo(phenylene vinylene), OPV, ligands exhibit modified optical properties such as suppression of blinking when compared to conventional TOPO covered or ZnS-capped CdSe quantum dots. The blinking suppression is shown to be highly sensitive to the degree of ligand coverage on the quantum dot surface and this effect is interpreted as resulting from charge transport from photoexcited OPV into vacant trap sites on the quantum dot surface. This direct surface derivatization of quantum dots with organic ligands also enables a “tunable” quantum dot surface that allows dispersion of quantum dots in a variety of polymer supported thin films without phase segregation. This facilitates straightforward inclusion of these new hybrid materials into solid state formats and suggests exciting new applications of composite quantum dot/organic systems in optoelectronic systems.

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.

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