Synthetic mimic of selective transport through the nuclear pore complex.

The nuclear pore complex is a large protein channel present universally in eukaryotic cells. It generates an essential macromolecular separation between the nucleus and cytoplasm. The transport mechanism relies on recognition of molecular cargos by receptor proteins, and on specific interaction between the receptors and the pores. We present a chemical mimic of this "receptor-mediated" transport using modified nanoporous membrane filters, polyisopropylacrylamide as the carrier molecule, or receptor, and single-stranded DNA as the cargo. We show that a complex of ssDNA and polyisopropylacrylamide diffuses faster through the modified pores than does the bare ssDNA, in spite of the larger size of the complex. The mobile polymer thus acts as a soluble receptor to usher a macromolecular cargo specifically through the pores.