Hi Bar,
What is your overall goal/plan for the LPS conjugation?
The reason I ask, this isn't a straightforward question. For one, "LPS" isn't just one thing: it varies greatly among Gram-negative species. Even within the same species (eg, E. coli), different strains can have great differences in the Lipid A (lipid anchors+Kdo), inner core (sugars just after the Lipid A), outer core (sugars just after the inner core), and O-antigen sections (including the inherent presence/smooth strain vs absent/rough strain aspect). Even within the same strain, things can change depending on growth conditions.
So, what might work for conjugation in one case might *not* work in another case.
The actual structure of X8 has not been formally declared by Fluidigm. However, the references of various data sheets and some talks given over the years basically imply that X8 is a shorter version of the linear polymer described here (
http://dx.doi.org/10.1002/anie.200700796 ), but with DTPA rather than DOTA as chelating groups.
Mike