The In agreement with previous observations , the molecular weight of the nucleic acid molecule had a significant impact on the kinetics of adsorption and the ultimate Gmax measured (Figure ). This is in agreement with the restricted infiltration of high molecular weight macromolecules into dense polymer brushes, in agreement with observations and modelling made in the case of non-strongly interacting brush-macromolecule pairs . Interestingly, the hybridisation state of RNA (dsRNA vs. ssRNA, 20 bp or bases) had little impact on the kinetics of adsorption and the ultimate adsorption levels of these molecules into PDMAEMA bushes. However, the type of nucleic acid materials had a significant impact on adsorption, with 20 bp dsRNA adsorbing to approximately The molecular weight of the nucleic acid molecules adsorbing and infiltrating into the brush had a significant impact on the apparent association constant kapp1, with mRNA and pDNA displaying constants 1-2 orders of magnitude higher than short RNA and DNA sequences (Figure ). In contrast, the apparent desorption constant kapp2 was far less sensitive to the molecular weight of the species adsorbing, but was found to be higher in the case of dsDNA 20 bp oligonucleotides and lower in the case of plasmid DNA. In turn, the affinity constants Ka measured reflected some of these changes in rate constants and were particularly sensitive to the molecular weight of the macromolecules infiltrating, with mRNA displaying a Ka > 1 order of magnitude higher than those of short oligonucleotide, irrespective of their chemistry, whereas pDNA displayed a Ka nearly 3 orders of magnitude higher than oligonucleotides (Figure ). Similarly, the binding factor a was found to be significantly enhanced for larger nucleic acid macromolecules, reflecting a reduced neutralisation of amines by phosphate groups, and associated reduced surface densities Gmax. The type of nucleic acid materials was also found to significantly impact a, with dsDNA 20 bp displaying a 2.2-fold increase in a compared to dsRNA 20 bp oligonucleotides with matching sequences. Together, these results suggesting a stronger driving force bringing large nucleic acid macromolecules at the surface of brushes (high kapp1 and Ka), but not enabling sufficient packing to achieve high surface densities, and therefore resulting in reduced Gmax and increased binding factors a. The type of nucleic acid molecules (e.g. DNA vs RNA double stranded 20 bp oligos) had a weaker yet still significant impact on the binding factor a and Gmax, but a negligible impact on Ka, suggesting that the electrostatic driving force regulating adsorption at the surface of polyelectrolyte brushes was comparable, but that altered interactions may impact the density and conformation of these molecules within the brush. Interestingly, the hybridisation state of RNA oligonucleotides had negligible effects on their adsorption to PDMAEMA brushes, although apparent rate constants of adsorption and desorption were found to be slightly higher in the case of double stranded RNA.