Label-free and rapid DNA characterization using gold nanoparticle monolayer-based field-effect sensors

Deoxyribonucleic acid (DNA) serves as the fundamental genetic blueprint for all living organisms, with each species possessing a distinct DNA sequence that is passed down to subsequent generations. The detection of DNA is crucial for identifying and diagnosing human diseases, particularly infectious diseases. Owing to specific molecular interactions between DNA and nanomaterials, nanostructured platforms can effectively facilitate DNA recognition and detection. In this study, a field-effect DNA biosensor was designed and fabricated using a perfectly assembled two-dimensional monolayer of gold nanoparticles (Au-NPs) as the active sensing medium, positioned between two metal electrodes separated by a 100 μm gap on a silicon oxide surface. The biosensor demonstrated the capability to differentiate between DNA molecules based on their net charge, which varies with the sequence composition and strand length. Interactions between DNA molecules and the Au-NP monolayer induced measurable changes in the current-voltage (I-V) characteristics, which were transduced into electrical signals for sensing. To quantify the sensitivity of the biosensor, synthetic DNA oligonucleotides were first employed. The AT-rich and GC-rich sequences yielded sensitivities of 0.268 mA·decade⁻¹ and 0.223 mA·decade⁻¹ , respectively, corresponding to the limit of detection values of 1.23 μM for Oligo 1 and 1.28 μM for Oligo 2. The device was subsequently validated using DNA samples extracted from human Burkitt’s lymphoma cell line BL30 and its Epstein-Barr virus-infected counterpart BL30-B95.8. These results demonstrate the potential of this Au-NP monolayer-based field-effect sensor for rapid, label-free, and selective DNA detection in clinical diagnostics.