Azobenzene has been widely used as a photoregulator due to its reversible photoisomerization, large structural change between E and Z isomers, high photoisomerization yield, and high chemical stability. On the other hand, some azobenzene derivatives can be used as universal quenchers for many fluorophores. Nucleic acid is a good candidate to be modified because it is not only the template of gene expression but also widely used for building well-organized nanostructures and nanodevices. Because the size and polarity distribution of the azobenzene molecule is similar to a nucleobase pair, the introduction of azobenzene into nucleic acids has been shown to be an ingenious molecular design for constructing light-switching biosystems or light-driven nanomachines. Here we review recent advances in azobenzene-modified nucleic acids and their applications for artificial regulation of gene expression and enzymatic reactions, construction of photoresponsive nanostructures and nanodevices, molecular beacons, as well as obtaining structural information using the introduced azobenzene as an internal probe. In particular, nucleic acids bearing multiple azobenzenes can be used as a novel artificial nanomaterial with merits of high sequence specificity, regular duplex structure, and high photoregulation efficiency. The combination of functional groups with biomolecules may further advance the development of chemical biotechnology and biomolecular engineering.
The regulatory functions of plant
miRNAs on mammalian bodies are
controversial, mainly because stability of the miRNAs in the digestive
tract, as the prerequisite for their cross-kingdom effects, has somehow
been overlooked. Hence, as the first stage of food ingestion, stability
of plant miRNAs in human saliva has been investigated. The results
show that plant miRNAs are of considerable resistance against salivary
digestion, as surviving miRNAs more than 20 fM are detected. The stability
varies dramatically, which can be explained by the difference in tertiary
structure, governing their affinities to RNase. Surprisingly, miRNAs
of low initial concentrations can end up with high survival rates
after digestion. Plant miRNAs can be loaded into exosome-like nanoparticles
(ELNs) and microcapsules formed by food components, both of which
protect the miRNAs from being degraded in human saliva. Overall, plant
miRNAs can apply certain strategies to maintain constant concentrations,
paving the way for their potential cross-kingdom effects.
A biosensor using two aptamers (Dual-Apt)
and cut-assisted rolling
circle amplification (CA-RCA) for rapid and visualized detection of Vibrio parahaemolyticus was established. The anchoring
aptamer (A-Apt) that specifically binds to the surface of V. parahaemolyticus was applied to separate and enrich
the bacterium from the food matrix with the help of streptavidin magnetic
beads. While the detecting aptamer (D-Apt), binding on the different
sites of the cell surface, was used as a signal reporter. CA-RCA with
an enhanced amplification rate was fabricated here to amplify the
D-Apt to produce the monomeric G4 sequence that catalyzes the oxidation
of ABTS2–, resulting in the coloration visible to
the naked eye. Under optimal conditions, as low as 10 colony-forming
units (CFU)/mL (g) of V. parahaemolyticus can be visibly detected in real food samples. Free from DNA extraction,
visualized signal output and no need for expensive instruments enable
Dual-Apt and CA-RCA to be a promising strategy for on-spot rapid detection.
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