The dense localization of DNA on soluble nanoparticles can lead to effects distinct from equivalent amounts of the DNA in solution. However, the specific effect may depend on the nature of the assembly and the nanoparticle core. Here we examine the accessibility of densely packed DNA duplexes that extend from a bottle-brush polymer core. We find that unlike spherical nucleic acids, the DNA duplex bristles on the bottle-brush polymer remain accessible to sequence-specific cleavage by endonucleases. In addition, the hybridized strand of the duplex can be displaced through a toehold-mediated strand exchange even at the polymer interface. These results demonstrate that the DNA on bottle-brush polymer remains sufficiently flexible to allow enzymatic degradation or DNA hybridization.