| AVS 55th International Symposium & Exhibition | |
| Biomaterial Interfaces | Thursday Sessions |
| Session BI-ThP |
| Session: | Biomaterial Interfaces Poster Session with Focus on Engineered Bio-Interfaces and Sensors |
| Presenter: | R.A. Shircliff, Colorado School of Mines |
| Authors: | R.A. Shircliff, Colorado School of Mines J.F. Fennell, Colorado School of Mines I.T. Martin, National Renewable Energy Laboratory P. Stradins, National Renewable Energy Laboratory S.G. Boyes, Colorado School of Mines M.L. Ghirardi, National Renewable Energy Laboratory S.W. Cowley, Colorado School of Mines H.M. Branz, National Renewable Energy Laboratory |
| Correspondent: | Click to Email |
The morphology and chemistry of functionalized silica surfaces have been characterized to understand key factors to surface uniformity and reproducibility of DNA immobilization and hybridization. Deposited 3-aminopropyltriethoxysilane (APTES) and 3-aminopropyldimethylethoxysilane (APDMES) layers were characterized by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), spectroscopic ellipsometry, thermogravimetric analysis, contact angle and DNA bioassays. DNA bioassays included fluorescence-based analysis and 32P-radiometric assays of DNA surface density. Angle-resolved XPS confirmed attachment of the sulfo-EMCS heterobifunctional crosslinker to amine-terminated layers deposited from both APTES and APDMES. High levels of immobilization of thiolated single-strand DNA to APTES-modified surfaces were observed by fluorescence from fluorescein dye attached to the DNA. Surprisingly, there was no detectable attachment of thiolated DNA to surfaces modified with monolayer films from APDMES. AFM of the APTES film revealed up to micron-scale island formations, which were likely caused by polymerization in the solution phase or on the surface. The APTES films also had significant variations of morphology under nominally identical deposition conditions, which may correlate with irreproducibility in DNA attachment. In contrast, the APDMES films had sub-nanometer surface roughness. Deposition of APTES, commonly used in DNA microarrays, showed high immobilization efficiency but lacked good reproducibility. APDMES films, which can only form a monolayer, showed reproducible monolayer films but lacked measurable DNA attachment. As an alternative to silane films, preliminary results will be reported on poly(ethylene glycol)-based films in order to improve reproducibility of DNA immobilization. We gratefully acknowledge the NREL Laboratory Directed Research and Development program for project funding. One of us (JFF) was supported by the U.S. Army.