attana - sensor technologies

Thermodynamic characterization

To investigate the processes that involve changes in temperature, transformation of energy, and the relationships between heat and work can easily be done by thermodynamic analysis of molecular interactions with all Attana systems.

Scientists study thermodynamics by knowing heat and thermal energy, where the amount of heat released or absorbed by a chemical reaction at constant pressure is called the enthalpy (ΔH), the dispersal of energy and matter is described by the thermodynamic state function entropy (ΔS).

Thermodynamics applies to a wide variety of topics in science. Biosensor is a good choice for thermodynamic analysis of molecular interactions. In the biosensor technique, one of the interacting molecules is immobilized and the binding of the other is followed. The thermodynamic parameters of molecules interaction can be determined by measuring the temperature dependence of the equilibrium constant derived from the ratio of the association and dissociation rate constants. Changes in enthalpy can be calculated directly from kinetic constants or from the equilibrium association constant in the standard state.

All Attana systems offer the possibility to measure thermodynamic parameters such as the enthalpy and entropy contributions of molecular interactions at temperatures ranging from 4 to 40 °C.  The Kon and Koff can be obtained at different temperatures and KD calculated. The kinetic data can be used to calculate ΔH° and ΔS°. The equations ΔG° = RTlnKD and ΔG° = ΔH° - TΔS° can be merged to: lnKD = ΔH°/RT - ΔS°/R and be employed for linear plots were ΔS° can be obtained from the y-axis intercept (ΔS°/R) and ΔH° from the slope (ΔH°/R). The thermodynamic properties of molecular interaction provide additional molecular information and thereby the possibility to select between molecular that for example have similar kinetics. Accurate information of the thermodynamic parameters, for example if a protein-protein interaction is enthalpy or entropy driven, has already been proven useful in pharmaceutical research. The advantage with this approach is to provide a real-time and label-free technique to measure thermodynamic parameters for selecting drug candidates.