Is it possible to accurately measure the size of nanoparticles in RPMI with 10% FBS by DLS? Could DLS measurement be disturbed by the scattering light from serum proteins.
Hi! I would suggest that the answer to your question depends on the behaviour of your NPs. Are proteins attaching to their surface? Additionally, it might be a bit problematic, if your contaminations (proteins) are present in high excess in comparison to your analyte (protein aggregates of larger size, maybe even as large as NPs), but this one you have to test out. Maybe spin filtration helps you a bit to purify your NPs. On the other hand, if you change the buffer too much, you also change the hydrodynamic size of your NPs. Finally, DLS is a good method, however, you have to be aware that it is biased to higher masses. Maybe you find GEMMA (number based gas phase electrophoresis) also applicable to your analyses... (Weiss, V. U. et al, 2013, Electrophoresis,Gas-phase electrophoresis of gelatin NPs). To sum up, determination of accurate NP size is not an easy task.
Hi there,
As Victor says, it may depend on your nanoparticle behaviour and properties but, in a general sense, I would say yes, it must affect. If not for specific interations, at least for simple aggregation phenomena or affecting the solvation shell.
For a view in this field, check the interesting articles form Dr Francesca Baldelli Bombelli (some below):
http://pubs.acs.org/doi/abs/10.1021/ja910675v
http://www.nature.com/doifinder/10.1038/nnano.2011.267
http://pubs.acs.org/doi/abs/10.1021/cr100440g
http://pubs.acs.org/doi/abs/10.1021/ja107583h
There might be the effect on viscosity and thus on results of DLS measurement.
If your NP is charged (positively or negatively), the NP will adsorb any protein inversely charged and provoke or the increase of the hydrodynamic size or the aggregation of your nanoparticles. Neutral NP are less sensitive to cell culture medium.
Note that the charge of the NP will also be very important for the uptake by cells (neutral NP almost no enter within cell, passively, whereas negative and positive NP enter much more due to their interactions with protein, and membrane proteins)
To answer your first question, yes nanoparticle size is altered due to exposure of nanoparticles to media. Nanoparticle's size increases in cell culture media due to two phenomena
1) Adsorption of proteins from serum
2) Agglomeration of nanoparticles due to ionic strength of the media
Both of these phenomena start simultaneously as soon as nanoparticles are exposed to media. Protein adsorption also increases stability of nanoparticles in high ionic strength media. Therefore, after some time you will get nanoparticles agglomorates covered with serum proteins which will be stable in that particular medium. You can check this by increasing ionic strength of media using NaCl. At very high ionic strengths you will see that the particle size observed is even higher.
To answer your second question, you might need information about viscosity of cell culture media to obtain exact size of agglomerates. In case of proteins, owing to their small size, scattering intensity is very low. You can run media as a control and see what is your DLS profile. Keep an eye on kcps. In case if your kcps for media is very low (
My answer would be: measure the size of the proteins in the 10% FBS uisng DLS and note the scattering intensity. Next measure the size of the NPs in 10% FBS and the scattered intensity. If the size difference is small: say less than a factor of three or the intensity difference is small less than a factor 10 you are pretty sure that the matrix influences the size of the NPs.
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