Characterisation and optimisation of an immunoprobe for triazines.

Area of Science:

• Biotechnology
• Analytical Chemistry
• Spectroscopy

Background:

• Label-free detection methods offer advantages in immunoassay development by simplifying assay procedures.
• Reflectometric Interference Spectroscopy (RIfS) is a sensitive optical transduction technique suitable for label-free biosensing.
• Immunoassays utilizing antibody fragments (Fab) can offer specific and efficient analyte binding.

Purpose of the Study:

• To characterize and optimize a novel optical immunoassay employing label-free detection.
• To investigate the impact of Fab-fragment concentration on assay performance and limit of detection.
• To understand the thermodynamic and transducer-related factors influencing immunoassay sensitivity.

Main Methods:

• Development and characterization of an optical immunoassay based on Reflectometric Interference Spectroscopy (RIfS).
• Sequential reaction scheme involving analyte-Fab fragment interaction followed by binding to a hapten-modified transducer.
• Systematic variation of Fab-fragment concentration (2x10⁻⁸ mol/L to 2.5x10⁻⁹ mol/L) to determine optimal conditions.

Main Results:

• Optimization of the immunoassay led to a reduction in the limit of detection down to a Fab-fragment concentration of 5x10⁻⁹ mol/L.
• Further decreases in Fab-fragment concentration did not improve the limit of detection, attributed to reduced analyte binding and antibody-transducer interaction.
• Thermodynamic principles and optical transducer performance were identified as key factors influencing the observed results.

Conclusions:

• The study successfully optimized a label-free RIfS immunoassay, demonstrating the importance of Fab-fragment concentration.
• Understanding the interplay between reaction thermodynamics, transducer characteristics, and assay format is crucial for achieving optimal immunoassay performance.
• The developed method provides a sensitive platform for label-free quantification of analytes.