Signal Amplification in Field Effect-Based Sandwich Enzyme-Linked Immunosensing by Tuned Buffer Concentration with...

Area of Science:

• Biosensors
• Electrochemistry
• Immunotechnology

Background:

• Miniaturized immunosensors offer advantages but suffer from reduced signal strength due to lower enzyme loading.
• Signal amplification strategies are essential to overcome limitations in miniaturized immunosensor designs.

Purpose of the Study:

• To develop and optimize signal amplification techniques for field-effect based electrochemical immunosensors using chip-based ELISA.
• To investigate the impact of buffer conditions on enzymatic reactions for signal enhancement.

Main Methods:

• Optimized molarities of phosphate-buffered saline (PBS) and KCl concentrations for signal amplification.
• Utilized an electrochemical impedance spectroscopy (EIS) device to measure voltage shifts.
• Validated buffer optimization using a commercial pH meter and on-chip immobilized enzymes.

Main Results:

• Identified optimal conditions of 100 μM PBS and 25 mM KCl for maximum signal amplification in solution.
• Observed similar trends on silicon chips, though with lower voltage shifts compared to bulk solution reactions.
• Achieved a greater than sixfold signal enhancement (8 to 47 mV) in chip-based sandwich immunoassays by adjusting PBS molarity.

Conclusions:

• Optimized buffer conditions significantly enhance signal amplification in chip-based electrochemical immunosensors.
• Immobilization of enzymes on chips can affect reaction kinetics (increased Km), necessitating careful buffer optimization.
• The developed method provides a viable strategy for improving sensitivity in miniaturized immunosensor platforms.