Contrast matching to understand solvent induced changes in morphology in dipeptide aggregates

We have a range of functionalised dipeptides that form micellar aggregates at high pH. We have recently found that we can modify the micellar aggregates by the addition of a co-solvent. The specific changes in morphology depend on the solvent used and are system dependent. We have excellent SAXS data, but now need to understand whether the co-solvent is part of the micellar aggregates or whether the changes are due to the changes in polarity, dielectric constant etc. Here, we wish to use contrast matching approaches to match out the dipeptide and see if the solvent is specifically present in the micellar aggregate or uniformly dispersed across the system.