A highly sensitive label-free electrochemical immunosensor based on poly(indole-5-carboxylicacid) with ultra-high...

Area of Science:

• Electrochemistry
• Materials Science
• Biosensors

Background:

• High redox signal stability is critical for electrochemical immunosensors.
• Existing redox-active species often lack stability and conductivity, limiting their use.
• Conductive polymers offer potential but require enhanced stability.

Purpose of the Study:

• To investigate the redox stability of poly(indole-5-carboxylic acid) (PIn-5-COOH).
• To develop a novel conductive polymer for advanced electrochemical immunosensor construction.
• To evaluate the performance of PIn-5-COOH in detecting alpha fetoprotein.

Main Methods:

• Synthesis and characterization of poly(indole-5-carboxylic acid) (PIn-5-COOH).
• Cyclic voltammetry (CV) to assess redox stability over 500 cycles.
• Fabrication of electrochemical immunosensors using PIn-5-COOH/MWCNTs-COOH nanocomposite.
• Performance evaluation for alpha fetoprotein detection, including linear range and detection limit.

Main Results:

• PIn-5-COOH demonstrated ultra-high redox stability, retaining 96.03% signal after 500 CV cycles.
• This stability surpasses most previously reported redox-active species (often <90% after 50 CV cycles).
• The PIn-5-COOH/MWCNTs-COOH based immunosensor achieved a wide linear range (0.001–100 ng/mL) and a low detection limit (0.33 pg/mL) for alpha fetoprotein.

Conclusions:

• The stable structure of PIn-5-COOH is key to its ultra-high redox stability.
• This conductive polymer provides a new platform for developing highly stable electrochemical immunosensors.
• The findings open new avenues for improved biosensing applications.