Field-effect sensors with charged macromolecules: characterisation by capacitance-voltage, constant-capacitance,...

Area of Science:

• Biosensing
• Materials Science
• Surface Chemistry

Background:

• Electrolyte-insulator-semiconductor (EIS) sensors offer label-free detection capabilities.
• Monitoring layer-by-layer adsorption of charged macromolecules is crucial for developing advanced sensor platforms.
• Deoxyribonucleic acid (DNA) detection is vital for diagnostics and molecular biology.

Purpose of the Study:

• To investigate the use of EIS sensors for detecting DNA immobilization and hybridization.
• To monitor the layer-by-layer adsorption of polyelectrolytes using EIS sensors.
• To characterize the sensor response to varying numbers and polarities of polyelectrolyte layers.

Main Methods:

• Capacitance-voltage (C-V) measurements
• Constant-capacitance measurements
• Impedance spectroscopy
• Atomic-force microscopy (AFM)

Main Results:

• EIS sensors successfully detected DNA immobilization and hybridization with distinct potential shifts (35-55 mV and 24-33 mV, respectively).
• Layer-by-layer adsorption of polyelectrolytes (PSS and PAH) resulted in alternating potential shifts of 30-90 mV per layer.
• Sensor response was sensitive to the number and polarity of adsorbed polyelectrolyte layers.

Conclusions:

• EIS sensors are effective for monitoring polyelectrolyte adsorption and detecting DNA interactions.
• The observed potential shifts provide insights into the surface charge changes during adsorption and hybridization.
• This work demonstrates the potential of EIS sensors for developing sensitive biosensing applications.