Photoresponsive DNA Monolayer Prepared by Primer Extension Reaction on the Electrode

Abstract

We describe a simple and convenient method for the preparation of photoresponsive DNA-modified electrodes using primer extension (PEX) reactions. A naphthalimide derivative was used as the photosensitizer that was attached to the C5-position of 2'-deoxyuridine-5'-triphosphate (dUTP(NI)). It has been found that dUTP(NI) is a good substrate for the PEX reactions using KOD Dash and Vent (exo-) enzymes in solutions to incorporate naphthalimide (NI) moieties into the DNA sequences. On the electrode surface immobilized with the primer/template DNA, the PEX reactions to incorporate dUTP(NI) molecules into the DNA sequence were found to efficiently proceed. With this solid-phase method, the DNA monolayers capable of generating photocurrent due to the photoresponsive NI molecule can be constructed. It was shown that the photocurrent generation was significantly suppressed by a single-nucleotide mismatch included in the primer/template DNA, which is applicable for the design of photoelectrochemical sensors to discriminate single-nucleotide sequences.

Photoresponsive Electrodes Modified with DNA Duplexes Possessing a Porphyrin Dimer

“…DNA possessing the disulfide‐protected linker attached at the 5′‐end of DNA through the C 6 alkyl linker was purchased from JBios (Japan) or prepared using thiol modifier C6 SS obtained from Glen Research. Oligonucleotides modified with a disulfide group at the 5′‐end were treated with 100 m m dithiothreitol in a 200 m m Na phosphate buffer (pH 7.0) to convert the disulfide into a thiol group, and then purified by reverse‐phase HPLC …”

“…Photocurrent measurements of DNA‐modified electrodes : Gold electrodes (0.02 cm 2 in area, BAS) were successively polished with 0.3 and 0.05 mm alumina (Buhler), etched in 1.0 m sulfuric acid, and rinsed with running milli‐Q water . The electrode surfaces were then treated with a solution of 10 μ m thiolated DNA in E‐buffer (20 m m Na phosphate buffer (pH 7.0) and 100 m m NaCl and 1 m m MgCl 2 ) for 30 min at RT.…”

Synthesis and Photophysical Properties of Fluorescence Molecular Probe for Turn-ON-Type Detection of Cytosine Bulge DNA

“…The development of molecular probes that can monitor biochemical processes by interacting with a particular analyte is an important area of research. In recent years, many fluorescent probes have been effectively used to monitor biochemical processes and assays. − One of the most important bioprobes is the fluorescent molecular probe for selective detection of specific DNA sequences and structures. − The key for successful design of these fluorescent probes is to maximize the fluorescence change in the absence and presence of the target DNA. Chemistry often used in these molecular probes involves Förster resonance energy transfer − and photoinduced electron transfer − because these interactions can be sensitively modulated by the analyte binding.…”