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An Ultrasensitive Light-up Cu(2+) Biosensor Using a New DNAzyme Cleaving a Phosphorothioate-Modified Substrate
Po-Jung Jimmy Huang1, Juewen Liu1
1Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada.
Analytical Chemistry
|February 10, 2016
Summary
Researchers developed a new Cu(2+)-specific RNA-cleaving DNAzyme, PSCu10, for biosensor applications. This highly selective DNAzyme offers improved stability and sensitivity without requiring unstable activators like ascorbate.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Environmental Science
Background:
- Copper ion (Cu(2+)) detection is crucial in various fields.
- Existing Cu(2+) biosensors often rely on DNAzymes with limitations like unstable activators.
- RNA-cleaving DNAzymes specific for Cu(2+) were previously unknown.
Purpose of the Study:
- To isolate novel Cu(2+)-specific RNA-cleaving DNAzymes.
- To characterize a new DNAzyme, PSCu10, for Cu(2+) detection.
- To develop a highly sensitive and selective Cu(2+) biosensor.
Main Methods:
- In vitro selection using a phosphorothioate (PS) RNA-containing library.
- Isolation and characterization of Cu(2+)-specific RNA-cleaving DNAzymes.
- Design and testing of a catalytic beacon sensor utilizing the isolated DNAzyme.
Main Results:
- A new Cu(2+)-specific RNA-cleaving DNAzyme, PSCu10, was isolated.
- PSCu10 exhibits optimal activity at pH 6.0 with a cleavage rate of 0.1 min(-1) at 1 μM Cu(2+).
- The R(p) diastereomer of PSCu10 is 37 times more active than the S(p) isomer; only Hg(2+) showed minor cleavage.
- A catalytic beacon sensor demonstrated a detection limit of 1.6 nM Cu(2+) with high selectivity and no interference from ascorbate.
Conclusions:
- PSCu10 is a novel, highly specific, and efficient RNA-cleaving DNAzyme for Cu(2+) detection.
- The developed biosensor offers superior sensitivity and selectivity compared to existing methods.
- This work provides a new tool for Cu(2+) analysis in biological and environmental samples.
