Covalent attachment and hybridization of DNA oligonucleotides on patterned single-walled carbon nanotube films

DNA oligonucleotides were covalently immobilized to prepatterned single-walled carbon nanotube (SWNT) multilayer films by amidation. SWNT multilayer films were constructed via consecutive condensation reactions creating stacks of functionalized SWNT layers linked together by 4,4'-oxydianiline. Aminated- or carboxylated-DNA oligonucleotides were covalently immobilized to the respective carboxylated or aminated SWNT multilayer films through amide bond formation using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. UV-vis-NIR spectroscopic analysis indicated that the SWNT film surface density increased uniformly according to the number of reaction cycles. Scanning electron microscopy and contact angle measurements of the SWNT multilayer film revealed a uniform coverage over the substrate surface. The covalent attachment of DNA oligonucleotides to the SWNT multilayer films and their subsequent hybridization with complementary oligonucleotides were verified using X-ray photoelectron spectroscopy and fluorescence-based measurements. This is the first report demonstrating that DNA oligonucleotides can be covalently attached to immobilized SWNT multilayer films. The anchored DNA oligonucleotides were shown to exhibit excellent specificity, realizing their potential in future biosensor applications.