Ultra trace analysis of small molecule by label-free impedimetric immunosensor using multilayer modified electrode

Area of Science:

• Electrochemistry
• Biosensors
• Nanotechnology

Background:

• Chloramphenicol is a banned antibiotic in food production due to health risks.
• Sensitive and selective detection methods are crucial for monitoring chloramphenicol residues.
• Existing detection methods often lack the required sensitivity or are complex.

Purpose of the Study:

• To develop a highly sensitive impedimetric sensor for ultra-trace level detection of chloramphenicol.
• To investigate the performance of a multilayer electrode modified with self-assembled thiourea monolayer (SATUM), gold nanoparticles (AuNPs), mercaptosuccinic acid (MSA), and antibody.
• To compare the analytical performance of different electrode modifications.

Main Methods:

• Fabrication of a multilayer electrode: SATUM/AuNPs/MSA/antibody.
• Impedimetric detection of chloramphenicol based on antibody-antigen complex formation.
• Optimization of electrode modification and detection parameters.
• Validation using real shrimp samples and comparison with HPLC-PDA.

Main Results:

• The SATUM/AuNPs/MSA/antibody electrode exhibited a wide linear range (0.50-10) × 10⁻¹⁶ M and an ultra-low determination limit of 1.0 × 10⁻¹⁶ M.
• This performance was superior to electrodes with fewer modifications (SATUM/AuNPs and SATUM).
• The sensor demonstrated good selectivity, reusability (up to 45 cycles), and stability (RSD < 4%).
• Results from shrimp sample analysis showed excellent agreement with HPLC-PDA.

Conclusions:

• The developed multilayer electrode offers a highly sensitive and selective platform for chloramphenicol detection.
• The impedimetric system provides a robust and reusable method for detecting ultra-trace levels of small molecules.
• This approach holds potential for monitoring other small molecules by adapting the affinity binding pairs.