Direct, Label-Free, and Rapid Transistor-Based Immunodetection in Whole Serum

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• Transistor-based biosensors offer scalable fabrication and label-free, real-time quantification for point-of-care diagnostics.
• A major limitation is the short Debye screening length in physiological samples, hindering direct serum measurements.
• Existing methods often require sample pretreatment, labeling, or washing steps, complicating point-of-care applications.

Purpose of the Study:

• To overcome the Debye screening length limitation in transistor-based biosensors for direct serum analysis.
• To enhance sensor response and performance through surface modification and optimized measurement conditions.
• To demonstrate sensitive and selective detection of human thyroid-stimulating hormone (hTSH) in whole serum.

Main Methods:

• Tailoring the biosensor's sensing surface with short, specific biological receptors and polyethylene glycol (PEG).
• Performing measurements at elevated temperatures (37 °C) to improve sensor performance.
• Utilizing transistor-based technology for label-free and real-time quantification.

Main Results:

• Surface tailoring with specific receptors and PEG significantly enhanced the transistor-based biosensor response.
• Elevated measurement temperatures (37 °C) further improved sensor performance.
• Achieved highly sensitive and selective detection of human thyroid-stimulating hormone in whole serum with subpicomolar detection limits.

Conclusions:

• The novel approach enables direct immunodetection of hTSH in whole serum without sample pretreatment, labeling, or washing.
• This represents the first demonstration of transistor-based biosensors for direct immunodetection in whole serum.
• The developed sensor is low-cost, integrable into portable devices, and competitive with central laboratory analyzers.