AVS 61st International Symposium & Exhibition
    Biomaterial Interfaces Tuesday Sessions
       Session BI+AS-TuA

Paper BI+AS-TuA2
XPS Binding Energy Shifts for DNA Brushes on Gold

Tuesday, November 11, 2014, 2:40 pm, Room 317

Session: Characterization of Biointerfaces
Presenter: Dmitri Petrovykh, International Iberian Nanotechnology Laboratory, Portugal
Authors: C.C.A. Ng, International Iberian Nanotechnology Laboratory, Portugal
D.Y. Petrovykh, International Iberian Nanotechnology Laboratory, Portugal
Correspondent: Click to Email
DNA biointerfaces are important in a wide range of existing and emerging applications, such as biosensors, functionalization of nanoparticles for biomedical applications, and self-assembly of complex and functional nanostructures. The complexity of many of the DNA biointerfaces created for such applications often limits the ability to unambiguously interpret the results obtained from spectroscopy measurements for such systems. A powerful and successful approach to improving the analytical capabilities has been based on creating robust and well-defined reference systems, which then provide the insight for data interpretation in more complex analyses. Brushes of oligo(dT) single-stranded DNA can be attached to gold either via terminal thiol linkers, or via terminal blocks of (dA) nucleotides. While the former method results in a brush of roughly upright oligo(dT) strands relatively weakly interacting with one another, the complementarity of (dA) and (dT) blocks within the same strand creates a possibility of intra-strand hairpin-like hybrids in the (dA)-anchored case. Varying the parameters of these DNA brushes and deposition solutions creates a series with expected variation of thickness, surface density, and intra-strand interactions. Gold substrate provides a convenient binding energy (BE) reference for accurate XPS measurements of the characteristic DNA peaks. Following this approach, we find an unexpected BE shift of a N 1s peak across the series of DNA brushes. Typical effects observed in organic films do not appear to account for the full magnitude of the observed shift, so we will discuss the possible interpretations of this effect and its relation to the structure of DNA brushes.