Cooperative dynamics of DNA-grafted magnetic nanoparticles optimize magnetic biosensing and coupling to DNA origami
Aidin Lak, Yihao Wang, Pauline J. Kolbeck, Christoph Pauer, Mohammad Suman Chowdhury, Marco Cassani, Frank Ludwig, Thilo Viereck, Florian Selbach, Philip Tinnefeld, Meinhard Schilling, Tim Liedl, Joe Tavacoli, Jan Lipfert
Abstract
click chemistry with a tunable grafting density, which enables the encapsulation of single MNPs inside a functional polymeric layer. We used several complementary methods to show that particle translational and rotational dynamics exhibit a sigmoidal dependence on the ssDNA grafting density. At low densities, ssDNA strands adopt a coiled conformation that results in minor alterations to particle dynamics, while at high densities, they organize into polymer brushes that collectively influence particle dynamics. Intermediate ssDNA densities, where the dynamics are most sensitive to changes, show the highest magnetic biosensing sensitivity for the detection of target nucleic acids. Finally, we demonstrate that MNPs with high ssDNA grafting densities are required to efficiently couple to DNA origami. Our results establish ssDNA grafting density as a critical parameter for the functionalization of MNPs for magnetic biosensing and functionalization of DNA nanostructures.