Ultrasensitive disposable apatasensor for reagentless electrocatalytic detection of thrombin: An O2-Dependent hemin-G4-aptamer assay on gold screen-printed electrodes

Lucía Gómez-Arconada, Ana Díaz-Fernández, Elena E. Ferapontova*

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

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Abstract

Serine protease thrombin is a strong neurotoxin produced by the injured brain and an Alzheimer's disease biomarker. To address its point-of-care testing (POCT), we adapted the O2-dependent aptamer assay for thrombin to gold screen-printed electrodes (Au SPE). The assay exploits reagentless (with no mediators) electrocatalytic activity of hemin-G4 DNAzyme in O2 reduction. Au SPEs modified with thiolated hemin-conjugated aptamer and PEG showed enhanced electrocatalytic activity in O2 reduction upon thrombin binding to the aptamer, then folding into the electroactive hemin-G4 DNAzyme structure. 0.5 fM thrombin were detected in aerated PBS and artificial cerebrospinal fluid, correspondingly, with the logarithmic linear range extending to 100 fM; dopamine, and uric and ascorbic acids did not interfere with electroanalysis. The disposable aptasensor met basic POCT requirements, with a minimal shelf life of 3 days. However, the reactivity and suitability of the Au SPE surface for thiol binding and electrocatalysis required special surface pre-treatment and modification protocols, and the fundamental problem of a long-term stability of thiol modification on gold should be addressed for practical applications of Au SPE-based apatasensors in POCT.

Original languageEnglish
Article number123456
JournalTalanta
Volume245
ISSN0039-9140
DOIs
Publication statusPublished - Aug 2022

Keywords

  • Aptasensor
  • Electrocatalysis
  • G4
  • Gold screen-printed electrodes
  • Hemin
  • Thrombin

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