Ratiometric electrochemical aptasensor based on functionalized graphene nanocomposites for detection of CA19-9

Area of Science:

• Electrochemistry
• Nanomaterials Science
• Biomedical Engineering

Background:

• Carcinogenic antigen 19-9 (CA19-9) is a crucial tumor marker for diagnosing and monitoring pancreatic and other cancers.
• Accurate and sensitive detection of CA19-9 is vital for early diagnosis and effective treatment.
• Existing detection methods may face limitations in sensitivity, selectivity, or practicality for routine clinical use.

Purpose of the Study:

• To develop a highly sensitive and selective ratiometric electrochemical aptasensor for CA19-9 detection.
• To utilize graphene nanocomposites functionalized with reduced graphene oxide (rGO), carboxylated multi-walled carbon nanotubes (cMWCNTs), and gold nanoparticles (AuNPs) for enhanced sensing performance.
• To establish a reliable method for quantitative CA19-9 analysis in complex biological matrices like serum.

Main Methods:

• Fabrication of a glassy carbon electrode modified with rGO-cMWCNTs/AuNPs nanocomposites.
• Covalent immobilization of an anthraquinone-2-carboxylic acid (cDNA-AQ) labeled aptamer complementary chain.
• Formation of a hybrid chain with a ferrocene (Fc)-labeled aptamer (Apt-Fc) via base pairing to create the sensing interface.
• Utilizing the ratio of electrochemical signals (I_Fc/I_AQ) for ratiometric detection of CA19-9.

Main Results:

• The constructed aptasensor demonstrated excellent selectivity, reproducibility, and stability.
• A good linear relationship was observed between the logarithm of CA19-9 concentration and the signal ratio (I_Fc/I_AQ) within the range of 1.0–1.0 × 10⁶ mU/mL.
• The limit of detection was determined to be 0.65 mU/mL.
• High recovery rates (94.12–97.83%) were achieved in actual CA19-9 spiked serum samples.

Conclusions:

• The ratiometric electrochemical aptasensor offers a promising strategy for the rapid and accurate detection of CA19-9.
• The sensor exhibits potential for practical clinical applications in tumor marker diagnostics.
• This approach provides a feasible platform for developing similar sensors for other cancer biomarkers.