AVS 46th International Symposium
    Biomaterial Interfaces Group Tuesday Sessions
       Session BI-TuA

Paper BI-TuA10
Photoisomerization and Photo-induced Alignment of Ordered Polymer Ultrathin Films Containing DNA and Polypeptide Layers: Possibilities for Optobioelectronic Substrates

Tuesday, October 26, 1999, 5:00 pm, Room 613/614

Session: Characterization of Biomaterial Interfaces
Presenter: R.C. Advincula, University of Alabama at Birmingham
Authors: R.C. Advincula, University of Alabama at Birmingham
Y. Wang, University of Alabama at Birmingham
E. Fells, University of Alabama at Birmingham
E. Wallace, University of Alabama at Birmingham
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Alternate polyelectrolyte deposition (APD) is a relatively new technique for fabricating multilayer ultrathin polymer films. Since the polymers are adsorbed from solution, it opens up the possibility for incorporating biological macromolecules such as proteins, or nucleic acids in the active site that may be interesting for biosensing or biocompatibility issues. In the case of DNA molecules, selectivity arises from the interaction with various specific DNA reagents such as intercalators and DNA-complementary (hybridization) interactions. The multilayer complex films are also good model systems to investigate interaction between polynucleotides and polypeptides. The advantage of ultrathin film geometries in substrate supported systems is that they allow direct structural analysis using X-ray, FT-IR, SPS, etc. on a number of substrates, e.g. ITO-, Gold- coated glass, Si, etc. In this work, we report the formation of highly ordered ultrathin films containing DNA and/ or Polylysine/ Azobenzene dye multilayers fabricated using the alternate polyelectrolyte deposition (APD) approach. An important modification is the incorporation of photoisomerizable azobenzene dyes in the films to explore the possibility of using these films for some optobioelectronic applications. The photoisomerization of the dyes were investigated with respect to thickness, irradiation parameters, pair combinations, etc. The formation of polypeptide-dye multilayer complexes resulted in photo-induced circular and linear dichroism. This was investigated using polarized UV-vis spectroscopy, ATR, and SPS configurations. The conformation of the polypeptide and the DNA was investigated by FT-IR. In-situ adsorption experiments were investigated using ellipsometry and QCM.