Development of a surface plasmon resonance based immunosensor for diclofenac quantification in water

Area of Science:

• Analytical Chemistry
• Biosensor Technology
• Environmental Science

Background:

• Diclofenac (DCF) is a widely used non-steroidal anti-inflammatory drug (NSAID) with potential environmental concerns.
• Accurate and sensitive detection methods for DCF in aqueous solutions are crucial for environmental monitoring.
• Existing detection methods may have limitations in sensitivity, speed, or cost-effectiveness.

Purpose of the Study:

• To develop and validate a Surface Plasmon Resonance (SPR) biosensor for the sensitive detection of diclofenac (DCF).
• To establish an inhibition immunoassay format using a hapten-protein conjugate for DCF detection.
• To evaluate the performance characteristics of the developed SPR biosensor, including limit of detection, limit of quantification, and precision.

Main Methods:

• Fabrication of an SPR sensor chip with a gold layer on a BK7 glass slide.
• Preparation of a diclofenac-bovine serum albumin (DCF-BSA) conjugate via covalent coupling.
• Immobilization of the DCF-BSA conjugate onto the gold surface using a self-assembled monolayer and covalent amide linkage.
• Development of an inhibition immunoassay format using anti-DCF antibodies and varying concentrations of DCF in aqueous samples.
• Characterization of the DCF-BSA conjugate using MALDI-TOF mass spectrometry.
• Performance evaluation including calibration curve generation, limit of detection (LOD), limit of quantification (LOQ), inter-day precision, and analysis time.

Main Results:

• Successful synthesis and confirmation of the DCF-BSA conjugate.
• Demonstrated SPR response correlating with DCF concentration in an inhibition format.
• Achieved a limit of detection (LOD) of 3.15 μg/L and a limit of quantification (LOQ) of 10.52 μg/L for DCF.
• Obtained high inter-day precision with a relative standard deviation (RSD) of 1.96%.
• Short analysis time of 10 minutes per sample.

Conclusions:

• The developed SPR biosensor provides a sensitive and rapid method for detecting diclofenac in aqueous solutions.
• This represents the first SPR biosensor developed for DCF detection utilizing a hapten-protein conjugate.
• The biosensor shows promise as a preliminary tool for monitoring diclofenac in environmental water samples.