DNA-based Fluorescent Sensors

Abstract

515Fluorescent sensors are useful tools that can detect the target analyte with high sensitivity. To date, various fluorescent sensors have been developed for applications in biological 1 and environmental fields 2 etc. In order to design fluorescent sensors, specific recognition for the target analyte is important. DNA, which is a significant molecule in biology, can be a functional sensing element because the molecule has sophisticated molecular-recognition ability.3 Single-stranded DNA (ssDNA) recognizes the complementary sequence strictly. Some kind of DNA selectively captures the target molecule as an aptamer. In addition, DNA is susceptible to modifications and cleavages by DNA-related enzymes in a rigorous manner. By utilizing these appealing features, many DNA-based fluorescent sensors have been reported in recent years.Yang et al. reported on a fluorescent sensor for kanamycin using the DNA aptamer and G-quadruplex DNA. 4 The sensor consists of two ssDNA, P1 and P2. When the kanamycin is added to the P1-P2 complex, P2, a DNA aptamer of kanamycin, binds to kanamycin, and P1 is released from the complex. The released P1 then forms G-quadruplex DNA that binds to N-methyl mesoporphyrin IX (NMM), resulting in a fluorescence enhancement. A fluorescent sensor for hemin based on competitive binding to G-quadruplex DNA between hemin and protoporphyrin IX (PPIX) was also reported.5 Hg 2+ fluorescent sensors, in which G-quadruplex structures are induced by the formation of T-Hg-T mismatches (T, thymine base), were reported using NMM 6 and thioflavin T (ThT) 7 as signal molecules, respectively. A fluorescent sensor for target DNA was reported based on the binding of ThT with G-quadruplex DNA. 8The stem-loop structure of DNA is also useful for fluorescent sensing. Sawamura et al. developed a fluorescence quenching assay for the detection of point mutations based on a ligase detection reaction (LDR). In positive control (LDR using mutant DNA), two primers are ligated to produce a hairpin-like molecular beacon, and the fluorescence is quenched. A fluorescent sensor for the detection of Hg 2+ was reported, in which a stem-loop structure is cancelled by the formation of a T-Hg-T coordination structure in the presence of ssDNA. 10A fluorescent sensor for target DNA and deoxyribonuclease I was developed based on cancellation of the hairpin structure of DNA on quantum dots (QDs). 11The combined use of the G-quadruplex and hairpin structure is also useful to construct fluorescent sensors. [6][7][8] Nucleases are applied to the construction of a DNA-based fluorescent sensing system. Zhu et al. were also developed. In addition, other DNA-based fluorescent sensors were also reported. Tsuchiya et al. developed fluorescent aptamer sensors that can detect interferon-γ (IFN-γ) and adenine compounds on cells.17 A detection method for cancer mutation based on LDR was reported using fluorescence resonance energy transfer from a donor QD to an acceptor fluorescent dye.18 A fluorescent sensor for Ag + was developed by utilizing specifi...

Screening of DNA Signaling Aptamer from Multiple Candidates Obtained from SELEX with Next-generation Sequencing

“…Since they change their conformation by complex formation with target molecules, fluorescence-labelled aptamers have attracted much attention for use as analytical probes, referred to as signaling aptamers. 6,7 The conventional strategy for developing a signaling aptamer is based on the addition of functional sequences 8 and the optimization of modified position of fluorophore with/without quencher to targeted single aptamer. However, design of signaling aptamers is complex due to the difficulty of predicting their conformational change.…”

An Ultrasensitive Electrochemical DNA Biosensor Based on Carboxylated Multi-walled Carbon Nanotube/Molybdenum Disulfide Composites for KRAS Gene Detection

“…However, these technologies rely on professional skills and high cost. In order to find a more convenient method for oligonucleotide sequence detection, researchers are combining the advantages of complementary base pairing of gene with other fields, such as electrochemiluminescence, 8 electrochemistry, 9,10 chemiluminescence, 11 fluorescence [12][13][14][15] and nanotechnology. 16 Herein, electrochemical DNA biosensors have received much interest concerning the property that they can provide a simpler and more cost-effective platform that is highly sensitive for DNA detection.…”