Label-free and reagent-less protein biosensing using aptamer-modified extended-gate field-effect transistors

Area of Science:

• Biotechnology
• Nanotechnology
• Biosensing

Background:

• Field-effect transistors (FETs) offer a platform for label-free biosensing.
• Aptamers are short DNA or RNA sequences that can bind specific targets with high affinity and specificity.
• Developing sensitive and specific protein detection methods is crucial for diagnostics.

Purpose of the Study:

• To develop aptamer-modified FET biosensors for detecting lysozyme and thrombin.
• To evaluate the performance of these biosensors in terms of sensitivity, specificity, and dynamic range.
• To assess the biosensors' functionality in complex biological matrices.

Main Methods:

• Covalent immobilization of aptamers on a gold electrode of an FET to form a self-assembled monolayer (SAM).
• Utilizing aptamer-based potentiometry in a multi-parallel microelectrode array format.
• Real-time monitoring of gate potential changes upon protein binding.

Main Results:

• The aptamer-FET biosensors successfully detected lysozyme and thrombin with dynamic ranges of 15.2-1040 nM and 13.4-1300 nM, respectively.
• Limits of detection were as low as 12.0 nM for lysozyme and 6.7 nM for thrombin.
• Robust signals were achieved even in 10% fetal bovine serum (FBS), demonstrating specificity and stability.

Conclusions:

• Aptamer-modified FET biosensors provide a sensitive and specific platform for protein detection.
• The developed technology is CMOS-compatible, enabling low-cost manufacturing, miniaturization, and integration.
• This approach holds promise for developing advanced diagnostic tools.