Streptavidin as CNTs and DNA Linker for the Specific Electronic and Optical Detection of DNA Hybridization

Abstract

Streptavidin was used as an interlinker between single-wall carbon nanotubes (SWNTs) and oligonucleotides for the electronic and optical detection of DNA hybridization. The aim of using streptavidin as a linker was to prevent nonspecific adsorption of biomolecules onto carbon nanotubes (CNTs) and also to prevent the aggregation of DNA strands or other contaminants to the source and drain electrodes that can modify the Schottky barrier. The electronic detection was performed by using arrays of CNTs field effect transistors (CNTFETs) and statistically significant changes in the threshold voltage and ION current were inferred. For the optical approach, a complementary DNA strand labeled with a dye was used, and the hybridization was detected by fluorescence microscopy. Streptavidin was noncovalently bonded to SWCNTs. Afterward, single-strand DNA modified with biotin was attached to the streptavidin, followed by DNA hybridization with the complementary DNA strand. Direct addition of the complementary DNA strand to the SWNTs covered with streptavidin was also performed to rule out any false hybridization positives due to nonspecific adsorption, and neither electrical nor optical responses were recorded. The results indicated that streptavidin efficiently prevents nonspecific adsorption of high-affinity molecules such as DNA onto CNTs. The wrapping of SWNTs with streptavidin allows both electrical and fluorescence detection of DNA hybridization.

Hybrids of Nucleic Acids and Carbon Nanotubes for Nanobiotechnology

“…Fluorescent spectroscopy and fluorescent microscopy revealed a peculiar quenching phenomenon [ 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 ]. Rao et al confirmed the binding of poly(rU) molecules using single-molecule fluorescence microscopy and Raman spectroscopy [ 127 ].…”

“…D’Souza et al used ssDNA hybrids to measure electron transfer in self-assemblies of ion-paired porphyrins employing (6,5) and (7,6) semiconductive SWNTs [ 131 ]. Martinez et al found that streptavidin was an effective linker between SWNTs and oligonucleotides, and therefore, streptavidin efficiently prevented the non-specific adsorption of high-affinity molecules, such as DNA, onto CNTs [ 134 ]. Judkins et al performed EPI-fluorescence microscopy (EFM) on DNA-SWNT hybrids to estimate their diffusion constants [ 137 ].…”

The molecular origin of the electrostatic gating of single-molecule field-effect biosensors investigated by molecular dynamics simulations

“…It should be noted that the localized gating mechanisms just described for single-point functionalization cannot necessarily be transposed to when the nanotube is functionalized over most of its surface. Indeed, two experimental studies using such functionalization -with coverage by streptavidin proteins 80 or wrapping by DNA strands 9 over the majority of the nanotube's surface -observed that DNA hybridization leads to an increase in the current, as opposed to what Sorgenfrei et al measured when using single-point functionalization. These cases present two major differences with our study:…”

Enhancing the Surface Sensitivity and Selectivity: Functionalization of Carbon Nanomaterials

“…For instance, streptavidin strongly ad-sorbed on CNTs structure by means of hydrophobic interactions. Taking advantage of this irreversible immobilization, a FET was developed for DNA detection [53]. To this aim, a biotin-modified ssDNA was attached to the SWCNT/streptavidin surface (Fig.…”