Nanoscale DNA Tetrahedra Improve Biomolecular Recognition on Patterned Surfaces

The bottom-up approach of DNA nano-biotechnology can create biomaterials with defined properties relevant for a wide range of applications. This report describes nanoscale DNA tetrahedra that are beneficial to the field of biosensing and the targeted immobilization of biochemical receptors on substrate surfaces. The DNA nanostructures act as immobilization agents that are able to present individual molecules at a defined nanoscale distance to the solvent thereby improving biomolecular recognition of analytes. The tetrahedral display devices are self-assembled from four oligonucleotides. Three of the four tetrahedron vertices are equipped with disulfide groups to enable oriented binding to gold surfaces. The fourth vertex at the top of the bound tetrahedron presents the biomolecular receptor to the solvent. In assays testing the molecular accessibility via DNA hybridization and protein capturing, tetrahedron-tethered receptors outperformed conventional immobilization approaches with regard to specificity and amount of captured polypeptide by a factor of up to seven. The bottom-up strategy of creating DNA tetrahedrons is also compatible with the top-down route of nanopatterning of inorganic substrates, as demonstrated by the specific coating of micro- to nanoscale gold squares amid surrounding blank or poly(ethylene glycol)-passivated glass surfaces. DNA tetrahedra can create biofunctionalized surfaces of rationally designed properties that are of relevance in analytical chemistry, cell biology, and single-molecule biophysics.