Divalent Cation Dependence Enhances Dopamine Aptamer Biosensing

Oligonucleotide receptors (aptamers), which change conformation upon target recognition, enable electronic biosensing under high ionic-strength conditions when coupled to field-effect transistors (FETs). Because highly negatively charged aptamer backbones are influenced by ion content and concentrat...

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Bibliographic Details
Published in:ACS applied materials & interfaces 2021-03, Vol.13 (8), p.9425-9435
Main Authors: Nakatsuka, Nako, Abendroth, John M, Yang, Kyung-Ae, Andrews, Anne M
Format: Article
Language:English
Subjects:
Aptamers, Nucleotide - chemistry
Benzothiazoles - chemistry
Biosensing Techniques - instrumentation
Biosensing Techniques - methods
Calcium - chemistry
Dopamine - analysis
Dopamine - chemistry
Electrochemical Techniques - instrumentation
Electrochemical Techniques - methods
G-Quadruplexes - drug effects
Magnesium - chemistry
Serotonin - analysis
Serotonin - chemistry
Transistors, Electronic
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Summary:Oligonucleotide receptors (aptamers), which change conformation upon target recognition, enable electronic biosensing under high ionic-strength conditions when coupled to field-effect transistors (FETs). Because highly negatively charged aptamer backbones are influenced by ion content and concentration, biosensor performance and target sensitivities were evaluated under application conditions. For a recently identified dopamine aptamer, physiological concentrations of Mg2+ and Ca2+ in artificial cerebrospinal fluid produced marked potentiation of dopamine FET-sensor responses. By comparison, divalent cation-associated signal amplification was not observed for FET sensors functionalized with a recently identified serotonin aptamer or a previously reported dopamine aptamer. Circular dichroism spectroscopy revealed Mg2+- and Ca2+-induced changes in target-associated secondary structure for the new dopamine aptamer, but not the serotonin aptamer nor the old dopamine aptamer. Thioflavin T displacement corroborated the Mg2+ dependence of the new dopamine aptamer for target detection. These findings imply allosteric binding interactions between divalent cations and dopamine for the new dopamine aptamer. Developing and testing sensors in ionic environments that reflect intended applications are best practices for identifying aptamer candidates with favorable attributes and elucidating sensing mechanisms.
ISSN:1944-8244
1944-8252
DOI:10.1021/acsami.0c17535