DNA Electrochemistry with Tethered Methylene Blue

Abstract

Methylene blue (MB′), covalently attached to DNA through a flexible C12 alkyl linker, provides a sensitive redox reporter in DNA electrochemistry measurements. Tethered, intercalated MB′ is reduced through DNA-mediated charge transport; the incorporation of a single base mismatch at position 3, 10, or 14 of a 17-mer causes an attenuation of the signal to 62 ± 3% of the well-matched DNA, irrespective of position in the duplex. The redox signal intensity for MB′–DNA is found to be least 3-fold larger than that of Nile blue (NB)–DNA, indicating that MB′ is even more strongly coupled to the π-stack. The signal attenuation due to an intervening mismatch does, however, depend on DNA film density and the backfilling agent used to passivate the surface. These results highlight two mechanisms for reduction of MB′ on the DNA-modified electrode: reduction mediated by the DNA base pair stack and direct surface reduction of MB′ at the electrode. These two mechanisms are distinguished by their rates of electron transfer that differ by 20-fold. The extent of direct reduction at the surface can be controlled by assembly and buffer conditions.

Voltammetry and molecular assembly of G-quadruplex DNAzyme on single-crystal Au(111)-electrode surfaces – hemin as an electrochemical intercalator

“…Electronic conductivity of redox metalloproteins and metalloenzymes 34,[36][37][38][39]55,56 , and of double strand DNA-based molecules [11][12][13][16][17][18][19]57,58 immobilized at electrochemical interfaces have been explored comprehensively. Electronic conductivity of "non-canonical" DNA forms, quadruplexes in particular have also been addressed, but such reports have only begun to appear much more recently [27][28][29][30][31][32][33] , and with little if any direct approach to interfacial ; (c) surface immobilized G-quadruplexes finally offer perspectives for ultra-sensitive detection of metal ions [40][41][42] , complex biomolecules such as peptides [23][24][25][26][27][28][29][30] , and perhaps other analytes.…”

“…Electron or hole "hopping", with full vibrational relaxation between each single-charge hop has emerged as an attractive mechanism for photo-induced OGN electronic conductivity. This notion is, however, faced with challenges in interfacial electrochemical ET in redox marked surface immobilized OGN molecules [11][12][13][17][18][19][20] . Much lower energies than in photochemical ET are involved here, questioning the feasibility of actual electron or hole generation (reduction and oxidation) in the nucleobase pairs in the electrochemical potential ranges accessible.…”

DNA sensing by electrocatalysis with hemoglobin

“…In order to demonstrate that the electrocatalytically amplified signal is generated via DNA-mediated CT, the signal suppression due to the incorporation of a single-base mismatch was examined. Previously, the degree of signal attenuation upon incorporation of a single-base mismatch indicated that MB covalently tethered to the DNA duplex through a flexible ðCH 2 Þ 12 linkage can be reduced by both DNA CT and direct surface reduction (43). Here, we utilized a shorter ðCH 2 Þ 8 linkage in order to reduce contributions from the direct surface reduction of MB.…”

“…Amino-modified DNA, as well as thiol-modified DNA, was purified through standard procedures, as previously reported (6). MB modified with a terminal carboxylic acid was synthesized and coupled to the amino modified DNA (43). All single-stranded DNA was purified by reverse-phase HPLC and characterized with matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry.…”

Immunosensing procedures for carcinoembryonic antigen using graphene and nanocomposites

“…If both the amines of thionine are dimethylated, the product tetramethylthionine is known as famous MB. Detailed electrochemistry of such dyes are well documented in the literature and deoxyribonucleic acid (DNA) electrochemistry with tethered MB has received considerable interest (Pheeney and Barton, 2012). The electron transfer from the excited MB to graphene is more efficient than to GO, owing to the different electrostatic attraction between the dye and graphene.…”