For the synthesis of the polyanion library, we chose linear as well as dendritic polyglycerol as polymer backbones. Polyglycerol is bio-inert, and the required negatively charged sulfate or carboxylate groups can be introduced via the free hydroxyls (Scheme 1). We successfully functionalized a linear and a dendritic version of the polyglycerol with similar sizes (~10 kDa after functionalization) with either sulfate or carboxylate groups with a degree of functionalization around 90%. This enabled us to determine how the specific functional group and backbone flexibility affected binding and modulation of inflammation. We also functionalized dendritic polyglycerol with different amounts of sulfate groups (40%, 70%, 90%) to assess the effect of increased charge density. Further, two larger polyglycerol sulfates were synthesized with final molecular weights of ~50 kDa and ~100 kDa to determine the effect of the polyanion size. Table provides an overview of the synthesized linear and dendritic polyglycerol sulfates and carboxylates as well as the results regarding their size, degree of functionalization, number of anionic groups and zeta potential. The corresponding NMR spectra are provided in the SI (SI a Molecular weight (Mn) was determined by gel permeation chromatography (GPC) for the unsulfated compounds and calculated according to the functionalization degree for the polyanions.