Hi Mike,

if you know the final lipid composition and concentration, and the size of the particles, you could calculate how many molecules of phospholipid you have per micelle (PL/micelle), calculating the surface area of the micelle divided by the area per phospholipid (area DPPC = 0.64 nm^2 (Edholm 2005) for instance).

Then you divide (PL/volume) / (PL/micelle ) and get micelle /volume

It's a good approximation.

Then you can also check with nanoparticle people, they have an instrument for that , like this one here>

https://www.malvernpanalytical.com/en/products/product-range/nanosight-range

If you have nanoparticle tracking analysis (NTA) instrument, it can measure the number of particles/mL.

Thank you very much to the both of you.

I have access to nanotracking light scattering microscopy (NLSM). I will determine concentration by NLSM and also calculate micelle concentration based on theoretical assumptions that matias has given to check if it works. I will post the results later on.

For everybody following/reading the question the paper referenced by Matias Moller is: Article Areas of Molecules in Membranes Consisting of Mixtures

Thank you!

Best Regards

Mike

Hi,

Regardless of the type of your carrier system (being lipid-based, polymeric, metallic, surfactant-based, vesicular, micellar, etc.) for efficient drug delivery or transfection or construction of safe and efficient nucleic-acid-based vaccines, precise stoichiometrical studies and dose determinations are obligatory.

Calculations of "particle number" (of the carriers) in a given volume of the therapeutic or vaccine formulation along with "encapsulation efficiency" along with carrier / active ratio evaluation are extremely vital.

The following manuscript presents simple ways to calculate number of carrier systems per unit volume:

Article Simple Equations Pertaining to the Particle Number and Surfa...

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Mozafari, M.R.; Mazaheri, E.; Dormiani, K. Simple Equations Pertaining to the Particle Number and Surface Area of Metallic, Polymeric, Lipidic and Vesicular Nanocarriers. Sci. Pharm. 2021, 89, 15. https://doi.org/10.3390/scipharm89020015

Hello Mike Lange , an interesting development in DLS is this concept of multi-angle DLS to get a(n improved) size distribution. The peaks in that size distribution can then mathematically lead to a concentration in terms of particles/mL for each peak. If you have really good DLS data, you may be able to apply that concept to your existing DLS data. There are some requirements (good data, need to know the optical parameters for the material, background of buffer, intensity of toluene standard) that may not make this feasible. In that case a measurement with multi-angle DLS might be a potential method.

If and only if your DLS existing data are good, you could try out the calculator in your existing software to estimate the concentration... Tools-Calculators-Concentration Utilities, some limited explanation at https://www.materials-talks.com/blog/2017/03/07/can-i-use-dls-for-xyz/

and there is a publication on the concept at Article Nanoparticle number concentration measurements by multi-angl...

Thank you for your comments. I will certainly try that out!