Hi Simin,

DLS does not have the capability to quantify nanomaterials. At best, it gives you information on the aggregation state (hydrodynamic diameter) of the materials. The solvent you should use should be determined by the question you want to answer. If you want to measure size or aggregation in deionized water, then you should suspend your nanomaterials in deionized water (I must add that pristine CNTs are VERY unstable in deionized water but several papers, which you can check out, have shown how to achieve some stability). If what you are interested in is the size or aggregation of CNTs in PDB then you should disperse the nanomaterials in PDB and analyze it directly in that. You may have to work with different concentrations of CNTs to see whihc one provides an ideal signal.

Best,

Yemi

Hi Simin

As in most of the cases DLS is being used for the analysis of size of nanosystems,  proteins and antibody aggregation, agglomerations in nanosystems and diffusion coefficients. But one of the research work demonstrating that the concentration of particles can also be determined based on the scattering intensity (https://link.springer.com/article/10.1007/s11095-012-0795-4).

If your CNT are agglomerating in PDB culture then  some extra measures must be taken for dispersion media selection like your CNT must be well dispersed (no agglomeration of CNT) in the media which is being using for scattering intensity measurement.  For media selection you can add some stabilizers in the dispersion media to prevent the agglomeration. The sample must be homogeneous. 

Then you can plot a graph between different concentration of CNT in media Vs Scattering intensity. Finally you will get a regression line and equation. Please go through the link you may find it useful.

https://link.springer.com/article/10.1007/s11095-012-0795-4