Immobilization of nucleic acids at solid surfaces: effect of oligonucleotide length on layer assembly.
This report investigates the effect of DNA length and the presence of an anchoring group on the assembly of presynthesized oligonucleotides at a gold surface. The work seeks to advance fundamental insight into issues that impact the structure and behavior of surface-immobilized DNA layers, as in, for instance, DNA microarray and biosensor devices. The present study contrasts immobilization of single-stranded DNA (ssDNA) containing a terminal, 5' hexanethiol anchoring group with that of unfunctionalized oligonucleotides for lengths from 8 to 48 bases. Qualitatively, the results indicate that the thiol anchoring group strongly enhances oligonucleotide immobilization, but that the enhancement is reduced for longer strand lengths. Interestingly, examination of the probe coverage as a function of strand length suggests that adsorbed thiol-ssDNA oligonucleotides shorter than 24 bases tend to organize in end-tethered, highly extended configurations for which the long-term surface coverage is largely independent of oligonucleotide length. For strands longer than 24 bases, the surface coverage begins to decrease notably with probe length. The decrease is consistent with a less ordered arrangement of the DNA chains, presumably reflecting increasingly polymeric behavior.
Gene Logic Inc., Gaithersburg, MD 20878, USA. asteel@genelogic.com
A B
AB
Steel
R L
RL
Levicky
T M
TM
Herne
M J
MJ
Tarlov
D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D006046:Gold; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013499:Surface Properties; D013873:Thionucleotides
D004277:DNA, Single-Stranded; D009838:Oligodeoxyribonucleotides; D013873:Thionucleotides; D006046:Gold; D004247:DNA