DNA-Coated Colloids

The Eiser group works on the self assembly of DNA-functionalized colloids since 2007 at the University of Amsterdam (Nieke Geerts and Tatjana Schmatko). At the Cavendish Laboratory, Zongyang Xing then did her PhD, working on microrheology of thermaly reversibe hydrogels of DNA nano-stars (Xing et al., PNAS 115 (32), 8137 (2018))

Why DNA?

Short, complementary DNA-strands, A and A' , densley packed on a colloid surface, provide a highly specific, short-anged attraction between the colloids. Most Important: Binding between complementary stands is goverened by hydrogen bonds and thus are fully reversible (N. Geerts, E. Eiser, Soft Matter, 6, 4647 (2010) ).

Thus we can introduce binding rules: in a mixture of equally sized polystyrene (PS) spheres half of them red and the other green fluorescent can be programmed such that red colloids only bind to other red ones while green ones only bind to green ones.

Bigels

In collaboration with Giuseppe Foffi's group we used the high selectivity and temperature dependence to generate two inter-percolating colloidal networks, which we call bigels. Simulations by the Foffi-group showed that when colloids with very short-ranged interactions are quenched into the spinodal decomposition region, the colloids stick upon touching, leading to an arrested phase separation. Short DNA strands provide such highly specific and interactions allowing us to create such porous systems (F. Varrato et al. “Arrested demixing: from gels to bigels”, PNAS 109, 19155 (2012)).

Whole-Genome Detection

In collaboration with the Group of Fangfu Ye (Chinese Accademy of Science, Beijing, China), we utilized the Mutivalency and Super-Secectivity concept () to develop DNA-coated colloids as simple but highly selective tool for the detection of bacterial whole genomes (Xu et al., PNAS 120(37), 2305995120 (2023)).

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