Second-order kinetic analysis of IAsys biosensor data: its use and applicability

Area of Science:

• Biophysical Chemistry
• Biosensor Technology
• Analytical Chemistry

Background:

• Kinetic analysis of biosensor data often assumes constant ligate concentration, which may not hold true.
• Dissociation phase analysis typically assumes negligible ligate concentration, problematic for high-affinity interactions.
• Existing models may not accurately represent complex binding scenarios with significant concentration changes.

Purpose of the Study:

• To derive analytical solutions for second-order differential kinetic equations in biosensor analysis.
• To develop a binding isotherm that accommodates dynamic changes in both ligand and ligate concentrations.
• To identify the conditions under which standard kinetic assumptions (pseudo-first-order) become invalid.

Main Methods:

• Derivation of analytical solutions for second-order differential kinetic equations.
• Development of a comprehensive binding isotherm model.
• Analysis of ligate depletion effects on association and dissociation kinetics.
• Investigation of concentration changes' impact on binding isotherm characteristics.

Main Results:

• Ligate depletion significantly affects association rate constants at low concentrations with high-capacity/affinity ligands.
• Dissociation phase rebinding is influenced by affinity, ligand capacity, and initial dissociation response.
• Ligate depletion alters binding isotherm shape, especially with high matrix capacities and high-affinity interactions.

Conclusions:

• Standard kinetic assumptions in biosensor analysis can be invalidated by ligate depletion.
• Accurate kinetic and isotherm interpretation requires models that account for dynamic concentration changes.
• The derived models provide a more robust framework for analyzing complex biosensor binding events.