Immunosensing prostate-specific antigen: Faradaic vs non-Faradaic electrochemical impedance spectroscopy analysis on...

Area of Science:

• Electrochemistry
• Biosensing
• Biomarker Detection

Background:

• Prostate-specific antigen (PSA) is a key biomarker for prostate cancer diagnosis and monitoring.
• Highly sensitive and specific detection methods are crucial for early and accurate diagnosis.
• Electrochemical Impedance Spectroscopy (EIS) offers a label-free and sensitive approach for biosensing applications.

Purpose of the Study:

• To develop and validate a highly sensitive electrochemical biosensor for prostate-specific antigen (PSA) quantification.
• To explore the efficacy of both Faradaic (f-EIS) and non-Faradaic (nf-EIS) modes for PSA detection.
• To establish a stable, specific, and repeatable detection platform for potential lab-on-chip applications.

Main Methods:

• Immobilization of anti-PSA monoclonal antibodies onto a gold electrode surface via carbodiimide chemistry for covalent conjugation.
• Characterization of the sensor surface using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy (XPS).
• Quantification of PSA using EIS in both f-EIS (monitoring charge transfer resistance and impedance) and nf-EIS (monitoring capacitance) modes.

Main Results:

• The f-EIS mode achieved a logarithmic detection range from 100 ng/ml down to 0.01 ng/ml with a sensitivity of 2.412 kΩ/log10([PSA] ng/ml) and a Limit of Detection (LOD) of 0.01 ng/ml.
• The nf-EIS mode demonstrated a logarithmic detection range from 5000 ng/ml down to 0.5 ng/ml, with a sensitivity of 8.570 nF/log10([PSA] ng/ml) and an LOD of 0.5 ng/ml.
• The developed biosensor exhibited excellent device stability, specificity to PSA, and repeatability.

Conclusions:

• The developed EIS-based biosensor provides a highly sensitive and specific method for PSA detection.
• Both f-EIS and nf-EIS modes are effective for PSA quantification, offering different detection ranges and sensitivities.
• This technology holds significant potential for the development of portable, lab-on-chip diagnostic systems for PSA monitoring.