Stop-flow Technique
Stop-flow Technique - Related Videos
09:39
Techniques for the Analysis of Extracellular Vesicles Using Flow Cytometry
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Cited by 31 •
2015
Many different methods exist for the measurement of extracellular vesicles (EVs) using flow cytometry (FCM). Several aspects should be considered when determining the most appropriate method to use. Two protocols for measuring EVs are presented, using either individual detection or a bead-based approach.
07:34
Schlieren Imaging: A Technique to Visualize Supersonic Flow Features
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2023
Source: Jose Roberto Moreto, Jaime Dorado, and Xiaofeng Liu, Department of Aerospace Engineering, San Diego State University, San Diego, CA Military jet fighters and projectiles can fly at incredible speeds that exceed the speed of sound, which means they are traveling at a supersonic speed. The speed of sound is the speed at which a sound wave propagates through a medium, which is 343 m/s. Mach numbers are used to gauge the flight speed of an object relative to the speed of sound. An object...
05:43
Topical Airway Anesthesia for Awake-endoscopic Intubation Using the Spray-as-you-go Technique with High Oxygen Flow
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Cited by 11 •
2017
The topical anesthetic lidocaine was atomized using a high oxygen flow through the working channel of a flexible intubating endoscope to achieve topical airway anesthesia for awake endotracheal intubation. We prefer this modified spray-as-you-go technique for endoscopic intubation to classical bolus application because of higher patient satisfaction and better compliance.
19:26
Measuring Intracellular Ca2+ Changes in Human Sperm using Four Techniques: Conventional Fluorometry, Stopped Flow Fluorometry, Flow Cytometry and Single Cell Imaging
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Cited by 30 •
2013
Intracellular Ca2+ dynamics are very important in sperm physiology and Ca2+-sensitive fluorescent dyes constitute a versatile tool to study them. Population experiments (fluorometry and stopped flow fluorometry) and single cell experiments (flow cytometry and single cell imaging) are used to track spatio-temporal [Ca2+] changes in human sperm cells.
03:40
In Vitro Photoacoustic Flow Cytometry: A Non-invasive Flow Photoacoustic Technique to Detect Nanoparticle-bearing Circulating Ovarian Cancer Cells
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2023
In this video, we present a photoacoustic flow cytometric detection of ovarian cancer cells bearing nanoparticles in a circulating in vitro flow chamber. This non-invasive technique successfully identifies circulating tumor cells in a flow system utilizing a contrast agent.
FAQs
Mixing establishes a common reaction start for the reactants, while stopping the flow creates a stable observation period. The instrument can then track signal changes without continued solution movement obscuring the reaction. This separation between reaction initiation and measurement helps resolve events occurring over short time intervals and supports calculation of time-dependent behavior and rate constants.
The readout is selected according to the reaction-dependent change that best reports the process under study. Stop-flow measurements may follow absorbance, fluorescence, or another signal as reactants interact, proteins change conformation, or binding proceeds. Choosing an appropriate signal allows the instrument to convert rapid molecular changes into a time-resolved record for analysis.
Short-lived intermediates can appear between the initial reactants and final reaction state, so conventional sampling may fail to capture them. By recording signal changes soon after mixing, the technique can reveal these transient stages and distinguish how a reaction progresses. That information helps researchers determine rate constants and evaluate mechanisms in biochemical systems.
The same time-resolved approach can be applied to enzyme kinetics, ligand binding, protein conformational changes, and other biomolecular interactions. Differences in the recorded signal over time provide a way to compare how quickly each process develops and whether transient behavior is present. This versatility makes the method useful across several classes of bioengineering reactions.
A typical measurement begins by placing the reactants into a flow system and allowing them to combine rapidly. The solution movement is then stopped abruptly, and the instrument records absorbance, fluorescence, or another signal across short time intervals. The resulting time course is analyzed to quantify reaction behavior, identify intermediates, or determine rate constants.
Rather than providing only an endpoint, the method produces a time-dependent record of the reaction. Researchers can use that record to examine how a signal changes immediately after mixing, detect reaction intermediates, and estimate rate constants. These outcomes reveal kinetic behavior that would be missed if measurements were based only on conventional sampling at later times.
In bioengineering, stop-flow measurements are useful when enzyme activity, ligand binding, protein conformational changes, or other biomolecular interactions occur too quickly for conventional sampling. The resulting kinetic information can guide development of biosensors, therapeutic proteins, diagnostic assays, and engineered biochemical systems by showing how rapidly relevant molecular processes proceed.