Peptide nucleic acid films and capsules: assembly and enzymatic degradation.

Sequence-directed hybridization of nucleic acids provides a high level of control for the bottom-up assembly of nanostructured materials. Altering the DNA sequence affords control and versatility over the film structure, but is limited by the chemical and physical properties of DNA. Here, we use DNA analogues, peptide nucleic acids (PNAs), to introduce new properties to multilayered thin films and retain the advantages of sequence-directed assembly. Thin films, formed by the layer-by-layer (LbL) assembly of PNA strands, were assembled from short PNA sequences on planar and colloidal substrates. In the case of PNA-coated particles, hollow capsules were obtained following removal of the sacrificial particle template. The PNA films were stable to both nuclease and protease degradation, and the nuclease degradation rate could be tuned by varying the amount of DNA incorporated into the films. These thin films may find use in biomedical applications.