Covalent linking DNA to graphene oxide and its comparison with physisorbed probes for Hg2+ detection

Abstract

Graphene oxide (GO) has attracted extensive research interest as a platform for DNA adsorption and biosensor development. While most researchers use simple physisorption of fluorescently labeled DNA, covalent sensors are less susceptible to non-specific probe displacement and minimize false positive results. In this work, three thymine-rich DNA probes of different lengths are modified on their 3-end with an amino group for covalent conjugation to GO. They also each contain an internally labeled fluorophore so that Hg Lake Ontario water is demonstrated.

Comparison of Graphene Oxide and Reduced Graphene Oxide for DNA Adsorption and Sensing

“…[6][7][8][9][10][11] In addition, amino-modified DNAs were covalently attached to the carboxyl groups on GO forming an amide bond, avoiding non-specific probe displacement. [12][13][14][15] Many DNA-related enzymes were also involved to introduce functions such as signal amplification. 16,17 Finally, DNA/GO conjugates were used to template materials synthesis such as metal nanoparticles, [18][19][20] and stacked GO sheets.…”

Reduced graphene oxide aerogel with packaged TiO2 nanoparticles as a promising adsorbent for the separation of DNA from human whole blood

“…GO has been used as a platform for the adsorption of single‐stranded DNA (ssDNA) by hydrogen bonding , aromatic stacking , or covalent conjugation . It is noteworthy that both GO and ssDNA are negatively charged, but GO can still strongly adsorb ssDNA owing to the above‐mentioned interactions and hydrophobic interaction .…”

Covalent and Noncovalent Functionalization of Graphene Oxide with DNA for Smart Sensing

“…Our group also compared Hg 2þ detection using both physisorbed and chemisorbed aptamers on GO ( Figure 9B). [110] The method was similar, but a major difference was the position of the fluorescent label. Due to the folding of the Hg 2þ aptamer upon target binding, the label was placed in the middle of the aptamer sequence, rather than the end.…”

“…Reproduced with permission. [110] Copyright 2016, Elsevier B.V. C) Detection of intracellular pH using an i-motif DNA labeled with Cy3, hybridized with Cy5-labeled anchored strand on GO. D) Confocal fluorescence micrographs of HeLa cells incubated with the sensor at different pH.…”