Advances in the DNA Nanotechnology for the Cancer Biomarkers Analysis: Attributes and Applications.

The most commonly used clinical methods are enzyme-linked immunosorbent assay (ELISA) and quantitative PCR (qPCR) in which ELISA was applied for the detection of protein biomarkers and qPCR was especially applied for nucleic acid biomarker analysis. Although these constructed methods have been applied in wide range, they also showed some inherent shortcomings such as low sensitivity, large sample volume and complex operations. At present, many methods have been successfully constructed on the basis of DNA nanotechnology with the merits of high accuracy, rapid and simple operation for cancer biomarkers assay. In this review, we summarized the bioassay strategies based on DNA nanotechnology from the perspective of the analytical attributes for the first time and discussed and the feasibility of the reported strategies for clinical application in the future.

Novel Single-Enzyme-Assisted Dual Recycle Amplification Strategy for Sensitive Photoelectrochemical MicroRNA Assay.

Herein, a novel single-enzyme-assisted dual recycle amplification strategy based on T7 exonuclease (T7 Exo) and a strand-displacement reaction (SDR) was designed to fabricate a photoelectrochemical (PEC) biosensor for sensitive microRNA-141 (miRNA-141) detection with the use of laminar bismuth tungstate (Bi2WO6) as photoactive material. Compared with a traditional enzyme-assisted dual recycle amplification strategy, the presented method could effectively refrain the enzyme interference reaction, reduce environmental sensitivity, and save cost. Here, hairpin DNA1 (H1) decorated on magnetic beads (MB) hybridized with target miRNA-141 to form an H1/miRNA-141 heteroduplex. With the introduction of hairpin DNA2 (H2)-labeled SiO2 (H2-SiO2), SDR was triggered between H2-SiO2 and H1, thus miRNA-141 was displaced from the H1/miRNA-141 heteroduplex and an H1/H2-SiO2 duplex was formed, realizing the reuse of the target. In the presence of T7 Exo, the H1/H2-SiO2 duplex was digested with the release of output DNA-SiO2. To enhance the target conversion rate, H1-MB was intactly released and cycled, which could initiate more T7 Exo digestion and free abundant output DNA-SiO2. Through such a process, a tiny miRNA-141 could induce substantial output DNA-SiO2, effectively improving the target amplification efficiency and detection sensitivity of a PEC biosensor. Furthermore, Bi2WO6 was modified on an electrode to provide a superior initial PEC signal due to its excellent electronic transformation capacity. With the introduction of output DNA-SiO2, the hairpin structure of H3 on the electrode was opened, making SiO2 close to the electrode surface, which significantly decreases the PEC signal. This work first established the PEC biosensor featuring a single-enzyme-assisted dual recycle amplification process for sensitive detection of biomarkers.

[Ru(dcbpy)2 dppz]2+ /Fullerene Cosensitized PTB7-Th for Ultrasensitive Photoelectrochemical MicroRNA Assay.

A new cosensitization photoelectrochemical (PEC) strategy was established by using a donor-acceptor-type photoactive material, poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7-Th), as a signal indicator, which was cosensitized with bis(4,4'dicarboxyl-2,2'-bipyridyl)(4,5,9,14-tetraazabenzo[b]triphenylene)ruthenium(II) ([Ru(dcbpy)2 dppz]2+ ) embedded in the grooves of the DNA duplex and fullerene (nano-C60 ) immobilized on the surface of DNA nanoflowers for microRNA assay. [Ru(dcbpy)2 dppz]2+ and nano-C60 could effectively enhance the photoelectric conversion efficiency (PCE) of PTB7-Th as a result of well-matched energy levels among nano-C60 , [Ru(dcbpy)2 dppz]2+ and PTB7-Th, leading to a clearly enhanced photocurrent signal. Meanwhile, a target recycling magnification technique based on duplex-specific nuclease was applied in this work to obtain higher detection sensitivity. The proposed biosensor demonstrated excellent analytical properties within a linear detection range of 2.5 fm to 2.5 nm and a limit of detection down to 0.83 fm. Impressively, this cosensitization PEC strategy offers an effective and convenient avenue to significantly improve the PCE of a photoactive material, resulting in a remarkably improved photocurrent signal for ultrasensitive and highly accurate detection of various targets.

A novel "signal on" photoelectrochemical strategy based on dual functional hemin for microRNA assay.

In this work, a novel "signal on" photoelectrochemistry (PEC) biosensor was constructed with dual-functional hemin as a signal quencher and electronic mediator for ultrasensitive target microRNA-141 assay with the assistance of T7 exonuclease (Exo)-initiated target amplification technology.