Method for determining active concentrations and/or kinetic interaction constants in complex biological samples by means of surface plasmon resonance

A method for determining, by surface plasmon resonance in complex biological samples, active concentrations of an analyte and optionally kinetic constants of interaction of the analyte with a ligand, comprising

• providing a surface plasmon resonance chip on which a capture agent specific to a ligand of the analyte is immobilized;
• capture, by the capture agent, of a control ligand that does not bind the analyte to be tested;
• passage of the sample over the chip, injected at a determined flow rate for a determined duration and obtaining a sensorgram for the control ligand;
• regeneration of the surface to remove the captured control ligand from the capture agent;
• capture, by the capture agent, of a ligand that binds the analyte to be tested;
• passage of the sample over the chip, injected at the same determined flow rate for the same determined duration and obtaining a sensorgram for the analyte;
• subtraction of the sensorgram obtained with the control ligand from the sensorgram obtained with the ligand that binds the analyte to be tested;
• and
• calculation of the active concentration of the analyte and optionally kinetic constants of interaction of the analyte with the ligand,
• and characterized in that the control ligand and the ligand that binds the analyte to be tested are of a similar mass and the control ligand and the ligand that binds the analyte to be tested are captured in equivalent amounts by the capture agent.