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Aptasensor development: elucidation of critical parameters for optimal aptamer performance.
Eva Baldrich1, Alexandre Restrepo, Ciara K O'Sullivan
1Nanobiotechnology and Bioanalysis Group, Department of Chemical Engineering, Universitat Rovira i Virgili, Avinguda Països Catalans 26, 43007 Tarragona, Spain.
Analytical Chemistry
|December 2, 2004
Summary
Aptamer assays require individual optimization of parameters like buffer and incubation conditions, as their 3D structure impacts binding. Mixed ELISA/aptamer assays offer low detection limits for targets like thrombin.
Area of Science:
- Biotechnology
- Analytical Chemistry
- Molecular Biology
Background:
- Aptamers are synthetic oligonucleotides with high affinity and sensitivity, serving as alternatives to antibodies in analytical devices.
- Unlike DNA probes, aptamer binding relies on specific 3D folding, which is sensitive to assay conditions.
Purpose of the Study:
- To systematically evaluate parameters affecting Enzyme Linked Aptamer Assay (ELAA) performance.
- To optimize and compare diverse ELAA and mixed ELISA/ELAA formats using a thrombin-binding aptamer.
Main Methods:
- Systematic evaluation of parameters including immobilization strategy, incubation time/temperature, and buffer composition.
- Optimization and comparison of various ELAA and mixed ELISA/ELAA sandwich and competition formats.
- Validation of results using nuclear magnetic resonance, electrophoresis, and surface plasmon resonance.
Main Results:
- Assay parameters significantly influence aptamer folding and binding efficiency, necessitating individual optimization for each aptamer.
- Mixed ELISA/ELAA sandwich formats achieved the lowest limit of detection (<1 nM thrombin).
- A competition ELAA demonstrated high sensitivity (1.8 nM) and a short assay time (1.5 hours).
Conclusions:
- Aptamers are unique binding molecules whose 3D structure formation is influenced by multiple assay parameters.
- Unlike antibody or DNA-based assays, general recommendations for aptamer assay optimization do not exist.
- Each aptamer-based assay requires specific optimization of conditions for optimal performance and reliability.