Beyond the Kd Gate: Establishing Signal Causality in Electrochemical Aptasensors
8 affiliations
- 1Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, 4700 Keele Street, Toronto, Ontario, Canada, M3J 1P3
- 2Department of Chemistry, Université de Sherbrooke, 2500 Boulevard de l’Université, Sherbrooke, Quebec, Canada, J1K 2R1
- 3Institute of Chemistry, Department of Physics and Mathematics
- 4São Paulo State University (UNESP
- 5Facultade de Ciencias
- 6Universidade da Coruña
- 7Faculty of Natural Sciences, Aarhus University, Gustav Wieds Vej 14, Aarhus C, Denmark, DK-8000
- 8Department of Chemistry “Ugo Schiff, University of Florence, Via della Lastruccia 3, Florence, Italy, 50019
Abstract
Electrochemical aptasensors combine aptamer-based molecular recognition with electrochemical transduction, but a signal correlated with nominal target concentration alone does not establish aptamer–target binding. Target addition or matrix exposure may alter solution composition, reporter or mediator chemistry, nucleic acid behavior, surface organization, electron-transfer kinetics, interfacial integrity, or surface fouling without aptamer–target complex formation. The Kd gate addresses this upstream problem by requiring auditable, construct-matched verification of aptamertarget binding in homogeneous, non-denaturing solution under sensing-relevant conditions. Passing the gate, however, does not show that an immobilized construct retains recognition or that recognition causes the electrochemical response. We propose a sequential framework in which the Kd gate qualifies the recognition reagent, controlled surface measurements establish retained recognition, transduction measurements determine whether retained recognition generates a measurable response, and signalcausality controls establish whether that response depends on recognition. It distinguishes solutionphase Kd,sol, surface-associated apparent Kd,app, and device-response midpoint C50. It links controls to alternative response pathways and separates claim classes: target-correlated, recognition-linked, mechanistic or thermodynamic, and intended-use. Aminoglycoside and doxorubicin lineages illustrate why sequence conversion, truncation, reporter conjugation, and immobilization require reassessment of recognition and signal attribution. The framework should guide electrochemical aptasensor development with independently supported recognition and intended-use performance claims.
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BibTeX
@misc{krylov2026beyond,
title = {{Beyond the Kd Gate: Establishing Signal Causality in Electrochemical Aptasensors}},
author = {Sergey N. Krylov and Philippe Dauphin-Ducharme and Paulo Roberto Bueno and Elena Ferapontova and Ilaria Palchetti},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009418/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009418/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Beyond the Kd Gate: Establishing Signal Causality in Electrochemical Aptasensors
AU - Sergey N. Krylov
AU - Philippe Dauphin-Ducharme
AU - Paulo Roberto Bueno
AU - Elena Ferapontova
AU - Ilaria Palchetti
PY - 2026
DA - 2026/09/24
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009418/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009418/v1
AB - Electrochemical aptasensors combine aptamer-based molecular recognition with electrochemical transduction, but a signal correlated with nominal target concentration alone does not establish aptamer–target binding. Target addition or matrix exposure may alter solution composition, reporter or mediator chemistry, nucleic acid behavior, surface organization, electron-transfer kinetics, interfacial integrity, or surface fouling without aptamer–target complex formation. The Kd gate addresses this upstream problem by requiring auditable, construct-matched verification of aptamertarget binding in homogeneous, non-denaturing solution under sensing-relevant conditions. Passing the gate, however, does not show that an immobilized construct retains recognition or that recognition causes the electrochemical response. We propose a sequential framework in which the Kd gate qualifies the recognition reagent, controlled surface measurements establish retained recognition, transduction measurements determine whether retained recognition generates a measurable response, and signalcausality controls establish whether that response depends on recognition. It distinguishes solutionphase Kd,sol, surface-associated apparent Kd,app, and device-response midpoint C50. It links controls to alternative response pathways and separates claim classes: target-correlated, recognition-linked, mechanistic or thermodynamic, and intended-use. Aminoglycoside and doxorubicin lineages illustrate why sequence conversion, truncation, reporter conjugation, and immobilization require reassessment of recognition and signal attribution. The framework should guide electrochemical aptasensor development with independently supported recognition and intended-use performance claims.
ER -