To further investigate the impact of polymer brush interactions with nucleic acid molecules on adsorption profiles and kinetics, interactions with the strong polyelectrolyte PMETAC brushes were investigated next (Supplementary Figures and). PMETAC brushes display a comparable chemical structure to PDMAEMA brushes, but are quaternised with a relatively small methyl residue, therefore modestly impacting the hydrophobicity and volume of the ammonium moieties present in these polymer structures at neutral pH. However, whereas PMETAC brushes are aprotic, PDMAEMA brushes, with a pKa close to 7.0 41 , can act both as proton donors and acceptors at neutral pH. Whilst the impact of the molecular weight of nucleic acid materials on adsorption to PMETAC was still clearly apparent and comparable to that observed on PDMAEMA, the impact of the nucleic acid type (DNA vs RNA) differed significantly. 20 adsorbed with comparable rate constants, Ka, binding factors and Gmax on PMETAC, compared to PDMAEMA brushes. However, the Ka and Gmax of RNA macromolecules was significantly reduced, whereas their binding factors significantly increased on PMETAC, compared to PDMAEMA brushes. This was also associated with an increase in the apparent dissociation constants kapp2 measured for RNA oligos adsorbing to PMETAC, whilst the increase of kapp1 was found to be weaker (Supplementary Figure ). Therefore, these data suggest that the hydrogen bonding capacity of PDMAEMA brushes may be contributing to the particularly strong binding capacity of these brushes towards RNA macromolecules, compared to DNA. This could be proposed to result from interactions with the hydroxyl groups in the 2' position of the ribose of the macromolecule backbone, able to interact with some of the unprotonated tertiary amines of PDMAEMA residues.