| AVS 55th International Symposium & Exhibition | |
| Biomaterial Interfaces | Tuesday Sessions |
| Session BI-TuM |
| Session: | Protein and Cell Interactions at Interfaces |
| Presenter: | D.Y. Petrovykh, Naval Research Laboratory and University of Maryland, College Park |
| Authors: | A. Opdahl, University of Wisconsin L.J. Whitman, Naval Research Laboratory D.Y. Petrovykh, Naval Research Laboratory and University of Maryland, College Park |
| Correspondent: | Click to Email |
DNA brushes with unique properties can be prepared using a new immobilization method that is based on the intrinsic affinity of adenine nucleotides for gold (Opdahl et al., PNAS, 104, 9-14, 2007). The general method uses block-oligonucleotides with sequences that follow a d(Ak-Tm-Nn) pattern: a block of k adenine nucleotides [d(Ak)], followed by a block of m thymine nucleotides [d(Tm)], and a short sequence of n (arbitrary) nucleotides [d(Nn)]. These block-oligonucleotides attach to gold via the d(A) blocks and present the rest of the strand for hybridization or for attachment of other molecular recognition ligands. The range of grafting densities produced by this immobilization method can be further extended by co-immobilizing the d(Ak-Tm-Nn) probe DNA with short d(Al) DNA that act as lateral spacers. We present two applications of this immobilization strategy. In the first, we use d(A) as a means to immobilize d(Nn) probes for hybridization. We find that the strategy results in reproducible and reversible hybridization behavior, offering practical advantages including low cost and resistance to nonspecific adsorption. Moreover, the high degree of control of probe spacing inherent to the method allows us to observe and quantify by both x-ray photoelecton spectroscopy (XPS) and surface plasmon resonance (SPR) the effects that surface density and conformation of DNA probes have on hybridization efficiencies. In the second application, the d(Nn) portion of the strand is replaced with a biotin functionality [d(Ak-Tm-biotin)]. Altering the length or mole fraction of the d(Al) lateral spacer systematically changes the surface coverage of biotin, allowing control over the amount of streptavidin (SA) that can be linked to the surface. The SA captured by the d(Ak-Tm-biotin) layer is stable and maintains activity towards addition of a subsequent layer of biotin-functionalized molecules. Control experiments also indicate that gold surfaces covered by d(A) oligos exhibit resistance to nonspecific adsorption of SA, both as a molecule and as SA-functionalized microbeads. Since many types of molecules can be functionalized with biotin, compatibility with biotin-SA opens the door to a broad range of applications based on DNA immobilization via d(A) blocks.
Current address for L.J.W.: National Institute of Standards and Technology, Gaithersburg, MD 20899.