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SELEX-derived potassium aptamers for robust detection in a physiological sodium background.
Qing Zhao1, Kaijun Chen2, Shiyuan Liu2
1College of Pharmacy, Heze University, Heze, 274015, PR China; Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
Biosensors & Bioelectronics
|June 1, 2026
Summary
Researchers developed novel DNA aptamers specifically for potassium (K+) detection. These new aptamers exhibit significantly higher affinity and selectivity for K+ compared to existing methods, even in complex biological samples.
Area of Science:
- Biochemistry and Molecular Biology
- Nucleic Acid Aptamer Technology
- Biosensor Development
Background:
- Potassium (K+) is essential for biological processes.
- Existing DNA-based potassium sensors utilize G-quadruplex (G4) sequences not originally selected for K+ binding.
- There is a need for high-affinity, selective DNA aptamers tailored for K+ detection.
Purpose of the Study:
- To perform the first SELEX (Systematic Evolution of Ligands by Exponential Enrichment) experiment targeting K+ ions.
- To isolate and characterize novel DNA aptamers with high affinity and specificity for K+.
- To evaluate the performance of these aptamers in complex biological matrices.
Main Methods:
- Systematic Evolution of Ligands by Exponential Enrichment (SELEX) using K+ as the target.
- Deep sequencing to identify enriched guanine-rich sequences.
- Circular Dichroism (CD) titration to determine binding affinities (Kd).
- Thioflavin T (ThT) fluorescence assays for response characterization.
- Assays conducted in the presence of sodium ions (Na+) and artificial urine.
Main Results:
- SELEX successfully enriched guanine-rich sequences, with K-R17-36 and K-R17-36a showing high affinity for K+ (Kd of 0.08 µM and 0.06 µM, respectively).
- These aptamers demonstrated over 7-fold higher affinity for K+ compared to commonly used sequences like the thrombin-binding aptamer (TBA) and human telomeric sequence (HTS).
- Dual-mode fluorescence responses (enhancement and quenching) were observed, improving K+ detection selectivity.
- The K-R17-36 aptamer maintained approximately 9-fold higher affinity for K+ than HTS in the presence of 150 mM Na+ and in artificial urine.
Conclusions:
- This study presents the first K+-selected DNA aptamers, offering a significant advancement in potassium sensing technology.
- The identified aptamers, particularly K-R17-36, are high-affinity and robust binders for K+ under physiological conditions.
- These aptamers provide a valuable tool for developing improved K+ detection methods and biosensors.
