A SPR-based immunosensor for the detection of isoproturon

Area of Science:

• Biosensing and Immunoassay Development
• Environmental Analytical Chemistry
• Surface Plasmon Resonance (SPR) Technology

Background:

• Monitoring herbicide residues like isoproturon (IPU) is crucial for environmental safety.
• Existing detection methods may lack sensitivity or reusability.
• Development of robust immunosensors is needed for efficient herbicide analysis.

Purpose of the Study:

• To demonstrate the proof of principle for a reusable SPR-based immunosensor for isoproturon monitoring.
• To develop and optimize an antibody immobilization strategy for enhanced sensor performance.
• To evaluate different detection formats for improved sensitivity and working range.

Main Methods:

• Utilized a surface plasmon resonance (SPR) immunosensor with a reusable antibody immobilization strategy.
• Employed a capture antibody (mAb TIB 172) for reversible immobilization of the detecting antibody (mAb IOC 7E1).
• Compared direct detection and indirect competitive inhibition assay formats for isoproturon detection.

Main Results:

• The developed immobilization strategy allowed for up to 120 regeneration cycles without loss of antibody activity.
• Direct detection was unsuitable for routine analysis due to high test midpoint and low SPR signal.
• An indirect competitive assay significantly enhanced immunosensor parameters, achieving a limit of detection (LOD) of 0.1 µg/l at low antibody surface coverage.

Conclusions:

• A reusable SPR immunosensor with a novel antibody immobilization technique is feasible for isoproturon monitoring.
• The indirect competitive assay format offers superior sensitivity and performance compared to direct detection.
• Optimized antibody surface density is critical for achieving desired sensitivity and working range in competitive SPR immunosensors.