Field effect in molecule-gated switches and the role of target-to-receptor size ratio in biosensor sensitivity

• Published in: Biosensors & bioelectronics Vol. 127; pp. 215 - 220
• Main Authors: Garrote, Beatriz L., Fernandes, Flavio C.B., Cilli, Eduardo M., Bueno, Paulo R.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15.02.2019
• Subjects: Debye screening; Molecular electrochemistry; Molecular transistor; Quantum capacitors; Redox switches; Thomas-Fermi screening; Quantum capacitors; Molecular transistor; Molecular electrochemistry; Debye screening; Thomas-Fermi screening; Redox switches
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2018.12.018

We demonstrated here that molecular redox films are electrochemical capacitive devices possessing specific field effect in which molecular moieties within films act as sensitive gates. We confirm that the field effect present in these redox switches is suitable in detecting, in a label-free manner (without needs of redox probe in the biological samples), biomarkers of essential importance for dengue, heart risks and inflammation, Parkinson's disease and tumors. Though the sensitiveness is high, it is governed by Thomas Fermi screening and thus depends on the target-to-receptor size ratio. Thus, we also demonstrated how this target-to-receptor size ratio affects the sensitivity. We concluded that the smaller the biological receptor the greater the sensitivity. Consequently, a larger molecular target associated with a smaller receptor provides a considerable (predictable) improvement of the sensitiveness. •We demonstrate the field-effect characteristics of molecular redox switches.•Uses of the field-effect to detect biomarkers for dengue, heart risks, inflammation, Parkinson's disease and tumors.•Investigate how the sensitivity is governed by field effect screening length.•Demonstrate how target-to-receptor size ratio controls the sensitivity.