Kinetic Exclusion Assay of Biomolecules by Aptamer Capture

Area of Science:

• Biochemistry
• Analytical Chemistry
• Molecular Biology

Background:

• DNA aptamers exhibit high affinity and specificity for target ligands, comparable to antibodies.
• Aptamers are increasingly utilized in analytical and therapeutic applications as alternatives to antibodies.
• Kinetic exclusion assay (KEA) technology offers a platform for aptamer-based sensing.

Purpose of the Study:

• To measure the binding affinity of fluorescent DNA aptamers to thrombin using KEA.
• To quantify thrombin concentration in solution using aptamer-based assays.
• To investigate complex binding behaviors of aptamers.

Main Methods:

• Utilized kinetic exclusion assay technology for aptamer-thrombin binding analysis.
• Generated standard binding curves by titrating aptamers with thrombin.
• Fitted binding data using a 1:1 binding model and a four-parameter logistic equation.

Main Results:

• Determined an effective dissociation constant (K_d) in the sub-nanomolar range for aptamer-thrombin binding.
• Observed that a simple 1:1 binding model did not fully describe the experimental data, suggesting complex binding stoichiometry.
• Successfully quantified "unknown" thrombin concentrations in mock samples within the picomolar to nanomolar range.

Conclusions:

• KEA technology effectively characterizes aptamer-thrombin binding kinetics and equilibrium.
• The study highlights the potential for aptamers to exhibit complex binding, necessitating advanced models for accurate characterization.
• KEA is a versatile technology for aptamer-based analytical applications, enabling precise analyte quantification.