Powerful Amplification Cascades of FRET-Based Two-Layer
Nonenzymatic Nucleic Acid Circuits
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Abstract
Nucleic
acid circuits have played important roles in biological
engineering and have increasingly attracted researchers’ attention.
They are primarily based on nucleic acid hybridizations and strand
displacement reactions between nucleic acid probes of different lengths.
Signal amplification schemes that do not rely on protein enzyme show
great potential in analytical applications. While the single amplification
circuit often achieves linear amplification that may not meet the
need for detection of target in a very small amount, it is very necessary
to construct cascade circuits that allow for larger amplification
of inputs. Herein, we have successfully engineered powerful amplification
cascades of FRET-based two-layer nonenzymatic nucleic acid circuits,
in which the outputs of catalyzed hairpin assembly (CHA) activate
hybridization chain reactions (HCR) circuits to induce repeated hybridization,
allowing real-time monitoring of self-assembly process by FRET signal.
The cascades can yield 50000-fold signal amplification with the help
of the well-designed and high-quality nucleic acid circuit amplifiers.
Subsequently, with coupling of structure-switching aptamer, as low
as 200 pM adenosine is detected in buffer, as well as in human serum.
To our knowledge, we have for the first time realized real-time monitoring
adaptation of HCR to CHA circuits and achieved amplified detection
of nucleic acids and small molecules with relatively high sensitivity