Brownian motion can be see in starch grains that are approx 1micrometre in diameter.
What is the maximum size of particle before they can no longer exhibit Brownian Motion?
Platelets are 2 micrometres in diameter and are only marginally more dense than plasma. There are studies of the effects of Brownian Motion in flowing fluids to mimic its effect in vivo, but I cannot find any reference to it being studied in plasma at rest.
Has anybody seen any studies of Brownian Motion in Platelets at rest in non-flowing plasma?
I worked with platelets and was never able to see Brownian motion. They are flat disks in the resting state, and about 3 um in diameter.
I'm skeptical about being able to see brownian motion in platelets.
Despite the similar density of plasma and platelets, one cannot ignore the fact that platelets are vesicles, their glycoprotein membrane , will contribute to the adhesion to the subendothlial matrix and cell-cell cohesions. Which will minimise the effect of brownian motion.
Please keep us updated if you encounter other findings.
The attached is a numerical simulation in a stokes flow case, some experimental work in this field (in a couette flow) can be found from early and mid 70s
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2535814/
I am too, and certainly any movement will be much reduced compared to pollen grains, if only because of the plasma viscosity and non-newtonian fluid properties. I hadn't thought of the plasticity of the platelet membrane which will also absorb the momentum forces of molecules hitting it.
However the origins of the question were to see, qualitatively, whether any Brownian effect would contribute to keeping the platelets in suspension for longer...
Hi Chris,
As Haneen suggests you may see Brownian motion, but the question is to what degree this motion is affected by relevant factors.
I have observed and quantified Brownian motion of embedded particles (spherical 1.1 microns diameter) in whole blood (not-flowing) away and in the vicinity of red blood cell membranes. I have also quantified the motion of naturally occurring large macro-molecules (600 - 800 nanometers) in plasma as well. Analytical theory based on the Brownian motion of the 1.1 artificial particles agreed with experimental values marginally. Without having tested larger particles I could expect that above 2 microns larger discrepancies would be expected. A publication will be out soon (I hope). I will let you know.
- Badges
- Science topic
- Similar topics
- Engineering
- Thermal Engineering
- Thermofluid
- Fluid Mechanics