Ultrasensitive Label-Free Detection of Free Thyroxine (T4) in Physiological Ranges Using Aptamer-Functionalized...

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• Thyroxine (T4) is crucial for metabolic and developmental processes.
• Current T4 quantification methods (immunoassays) are centralized and slow.
• Need for rapid, point-of-care thyroid hormone monitoring exists.

Purpose of the Study:

• To develop a label-free biosensing platform for quantitative T4 detection.
• To utilize silicon nanowire field-effect transistors (SiNW-FETs) functionalized with DNA aptamers.
• To enable sensitive and selective real-time T4 monitoring.

Main Methods:

• Fabrication of SiNW-FETs functionalized with T4-specific DNA aptamers using TESPSA silanization.
• Real-time electrical detection of T4 in undiluted phosphate-buffered saline.
• Validation of sensor specificity using control devices and non-target molecules.
• Analysis of dose-response using the Hill model.

Main Results:

• Achieved label-free, real-time T4 detection in the physiological range (5-30 pM).
• Demonstrated a low limit of detection (~5 pM) and high linearity (R² = 0.9931).
• Confirmed sensor specificity and stable performance in relevant buffer conditions.

Conclusions:

• Aptamer-functionalized SiNW-FETs offer a sensitive and selective platform for T4 quantification.
• The biosensor shows potential for miniaturization and point-of-care thyroid hormone monitoring.
• This technology advances real-time diagnostics for endocrine health.