Iodide Quenching
Iodide Quenching - Related Videos
10:57
Quenching and Boiling
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2023
Source: Alexander S Rattner, Sanjay Adhikari, and Mahdi Nabil; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA Controlled heating followed by rapid cooling is an important element of many materials processing applications. This heat-treating procedure can increase material hardness, which is important for cutting tools or surfaces in high wear environments. The rapid cooling stage is called quenching, and is often performed by immersing...
09:09
Annexin V and Propidium Iodide Labeling
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2023
Staining with annexin V and propidium iodide (PI) provides researchers with a way to identify different types of cell death—either necrosis or apoptosis. This technique relies on two components. The first, annexin V, is a protein that binds certain phospholipids called phosphatidylserines, which normally occur only in the inner, cytoplasm-facing leaflet of a cell’s membrane, but become “flipped” to the outer leaflet during the early stages of apoptosis. The second component is the DNA-binding...
07:34
Modified Annexin V/Propidium Iodide Apoptosis Assay For Accurate Assessment of Cell Death
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Cited by 543 •
2011
An accurate method for the assessment of cell death is described. The protocol improves upon conventional Annexin V/ propidium iodide (PI) protocols, which display up to 40% false- positive events in cell lines and primary cells from a broad range of animal models.
07:47
Anti-virulent Disruption of Pathogenic Biofilms using Engineered Quorum-quenching Lactonases
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Cited by 7 •
2016
Quorum-quenching enzymes are anti-virulent and anti-bacterial options that can mitigate pathogenesis without risk of incurring resistance, by preventing the expression of virulence factors and genes associated with antibiotic resistance and biofilm formation. In this study, we report a method that demonstrates the efficacy of quorum-quenching enzymes in bacterial biofilm disruption.
08:58
Cerebral Blood Oxygenation Measurement Based on Oxygen-dependent Quenching of Phosphorescence
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Cited by 27 •
2011
We present an experimental procedure for measuring the partial pressure of oxygen (pO2) in cerebral vasculature based on oxygen-dependent quenching of phosphorescence. Animal preparation and imaging procedures were outlined for both large field of view CCD-based imaging of pO2 in rats and 2-photon excitation based imaging of pO2 in mice.
FAQs
Iodide ions reduce emission through dynamic, collisional encounters with fluorophores in the excited state. The interaction provides a pathway for the excited fluorophore to lose energy without producing as much detected fluorescence. Consequently, the amount of signal reduction depends on how readily iodide can reach the fluorescent molecule during its excited-state lifetime.
A Stern–Volmer relationship connects the change in fluorescence emission with iodide-mediated quenching. Researchers can use the extent of signal loss to evaluate how accessible a fluorophore is to the surrounding solution. Stronger quenching indicates greater exposure, whereas limited quenching is consistent with shielding by a protein, membrane, or cellular compartment.
Accessibility provides indirect information about a fluorophore’s molecular environment. A label exposed to surrounding solution can encounter iodide more readily than one buried or shielded within a biological structure. Comparing these responses helps researchers infer aspects of protein organization, membrane structure, or compartmental arrangement without relying only on fluorescence intensity itself.
A typical analysis compares fluorescence emission before and after exposure to iodide ions, then evaluates how the signal changes as quenching occurs. The measured reduction can be examined with a Stern–Volmer relationship to estimate relative accessibility. This workflow links an optical measurement to the fluorophore’s position within a biological molecular environment.
The method is useful when researchers need to distinguish fluorescent groups that remain exposed from those protected within proteins or membranes. In protein studies, the accessibility pattern can contribute to investigations of folding. In membrane studies, it can reveal differences in how fluorophores relate to surrounding solution and membrane structure.
Binding and conformational changes can alter whether a fluorophore is accessible to iodide ions. Researchers can monitor corresponding differences in fluorescence quenching to obtain indirect evidence that the fluorophore’s molecular environment has changed. This makes the approach relevant for examining biomolecular organization, molecular binding, and structural transitions in biological systems.