12 October 2005 Potential for optical DNA biosensors and biochips based on a GaAs substrates
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Biosensors and biochips can determine the presence of nucleic acid sequences in a test sample through fluorescence detection of hybridization between an immobilized nucleic acid (probe) and a nucleic acid in a test sample (target). The finding that the control of the environment of immobilized single-stranded probe molecules on fused silica surfaces can be used to tune selectivity to facilitate detection of even single base pair mismatches provides opportunities for design of novel biochips. We have typically used silane coupling agents to activate silicon and silicate surfaces for subsequent immobilization of biomolecules for development of optical biosensors. A self-assembled immobilization providing good structural order would be preferred. Studies have been done using thiol-terminated reagents for assembly of oligonucleotides on GaAs substrates. The spacing of Ga and As can be controlled across a surface, and in turn provides a template to control the density of self-assembled oliogonucleotide. Initial experimental work has begun using homogeneous GaAs surfaces, and the homogeneity and surface morphology of immobilized oligonucleotide films grown onto GaAs has been characterized by atomic force microscopy (AFM) and fluorescence methods. Cycles of hybridization and denaturation suggest that the GaAs provides a surface that is stable to loss of immobilized oligonucleotide, but that efforts to protect from non-selective adsorption are essential. Data suggested that the films were of monolayer thickness, and that it was possible to induce the presence of nodules of approximately 10-50 nm in diameter.
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Yun Ye, Yun Ye, April K. Y. Wong, April K. Y. Wong, Ulrich J. Krull, Ulrich J. Krull, } "Potential for optical DNA biosensors and biochips based on a GaAs substrates", Proc. SPIE 5969, Photonic Applications in Biosensing and Imaging, 59690L (12 October 2005); doi: 10.1117/12.628713; https://doi.org/10.1117/12.628713

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