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Label-free electrical detection of consecutive deoxyribonucleic acid (DNA) hybridization/denaturation by means of an array of individually addressable field-effect-based nanoplate silicon-on-insulator (SOI) capacitors modified with gold nanoparticles (Au-NP) is investigated. The proposed device detects charge changes on Au-NP/DNA hybrids induced by the hybridization or denaturation event. DNA hybridization was performed in a high ionic-strength solution to provide a high hybridization efficiency. On the other hand, to reduce the screening of the DNA charge by counter ions and to achieve a high sensitivity, the sensor signal induced by the hybridization and denaturation events was measured in a low ionic-strength solution. High sensor signals of about 120, 90, and 80 mV were registered after the DNA hybridization, denaturation, and re-hybridization events, respectively. Fluorescence microscopy has been applied as reference method to verify the DNA immobilization, hybridization, and denaturation processes. An electrostatic charge-plane model for potential changes at the gate surface of a nanoplate field-effect sensor induced by the DNA hybridization has been developed taking into account both the Debye length and the distance of the DNA charge from the gate surface.
Sensing charged macromolecules with nanocrystalline diamond-based field-effect capacitive sensors
(2008)
A new approach for a label-free electrical detection of DNA hybridization and denaturation using an array of individually addressable field-effect nanoplate SOI (silicon-on-insulator) capacitors functionalized with gold nanoparticles is presented. By using a constant-capacitance measuring setup in a differential mode, signal changes of ∼110 mV and ∼70 mV have been registered after the DNA hybridization and denaturation events, respectively.