The site-directed covalent immobilization of amino-terminated DNA oligonucleotides on microstructured patterns at silicon surfaces generated by the methodology of electron beam (EB) lithography was investigated. The microstructured patterns characterized by scanning electron microscopy (SEM) revealed remarkably regular in size and shape. After treatment with different time of activation (10s and 30min), self-assembled layers of 3-aminopropyltriethoxysilane (APTES) on silicon surfaces characterized by X-ray photoelectron spectroscopy (XPS) were demonstrated to obtain similar N 1s peaks. The immobilization specificity was evaluated by means of 5′ amino-modified oligonucleotides labeled with Cy 5 at its 3′ end attached onto microstructured patterns. The high-density DNA array (40,000 spots per cm2) was achieved, and the resulting array exhibited the specific binding due to DNA-DNA interaction. Additional studies indicated hardly visible signals when non-complementary probes were immobilized on the microstructured patterns. The deposition of DNA in a microstructure array using this technique is precise and homogeneous, showing the potential for high-density information storage and the miniaturization for biosensors and biochips.
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