AVS 51st International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI2-WeM

Paper BI2-WeM5
XPS and SIMS Characterization of Oligonucleotide Immobilisation via Patterned Plasma Polymerized Interlayers

Wednesday, November 17, 2004, 9:40 am, Room 213C

Session: Oligo Nucleotide - Surface Interactions
Presenter: P-C. T. Nguyen, University of South Australia
Authors: P-C. T. Nguyen, University of South Australia
R. Metz, University of South Australia
S. Kumar, University of South Australia
M. DeNichilo, TGR BioSciences, Australia
N. Voelcker, Flinders University of South Australia
M. Jasieniak, University of South Australia
S. Coultas, Kratos Analytical Ltd, UK
S. Hutton, Kratos Analytical Ltd, UK
H.J. Griesser, University of South Australia
Correspondent: Click to Email
Surface immobilised oligonucleotides are an attractive choice as recognition elements in microarrays for parallel, multidimensional, high throughput analysis in many biosensing applications. We investigate the physico-chemical factors affecting efficient oligonucleotide immobilisation and patterning. Furthermore, by using patterned plasma polymer coatings, we implemented a direct, one-step method of fabricating microdot arrays with specific surface chemistries onto which oligonucleotides can be covalently immobilised. Amino terminated oligonucleotides such as 15-T are immobilised via surface aldehyde groups of plasma polymerised polymers. Propanal plasma polymer coatings have been applied to a wide variety of substrates including silicon and Teflon. A mask containing 100 µm diameter holes was used during plasma polymerisation to produce an array of distinct aldehyde surface chemical regions for oligonucleotide immobilisation. XPS analysis of the plasma polymer and the immobilised oligonucleotides gave rise to the expected C, O, N and P peaks. Using atomic concentration, surface coverage is calculated as a measure of immobilisation efficiency. SIMS spectra revealed characteristic thymine containing fragments from the immobilised oligonucleotides. MALDI-MS verified the covalent attachment of the oligonucleotides and their ability to hybridise a complementary strand of 15-A oligonucleotide. Hybridisation kinetics studies are underway. SIMS imaging is used to document the spatial patterns formed by masked plasma deposition and to assess the spatial selectivity of oligonucleotide immobilisation. Small spot XPS will be used to quantify the composition of the microarray dots. Results to date demonstrate that the plasma deposition step, both patterned and unpatterned, is readily transferable to various substrates including Si wafer, Teflon PTFE and Teflon PFA.