Planar Disk μ-Aptasensors by Monolayer Assembly in a Dissolving Microdroplet

Area of Science:

• Electrochemistry
• Biosensors
• Nanotechnology

Background:

• Electrochemical aptamer-based sensors (EABS) offer modularity for real-time small molecule monitoring.
• EABS are valuable for analyzing complex biological samples and nanoscale systems.
• Sensor signal-to-noise ratio is limited by electroactive surface area, hindering miniaturization on ultramicroelectrodes.

Purpose of the Study:

• To develop a method for miniaturizing EABS on ultramicroelectrodes.
• To enhance the signal-to-noise ratio of EABS without increasing electrode surface area.
• To enable robust sensor fabrication for real-time analysis of small molecules.

Main Methods:

• Employed a concentration enrichment strategy using an aptamer-containing microdroplet.
• Utilized active dissolution of the microdroplet on an ultramicroelectrode submerged in an organic phase (1,2-dichloroethane).
• Investigated thiol-terminated aminoglycoside aptamer immobilization and sensor performance via voltammetry.

Main Results:

• Demonstrated consistent voltammetric signal increase correlated with droplet lifetime, indicating successful aptamer immobilization.
• Observed a diagnostic methylene blue peak and a 10-fold current increase compared to bare microelectrodes.
• Reported robust sensor behavior with a linear dynamic range from milli- to micromolar kanamycin concentrations.

Conclusions:

• Successfully fabricated and miniaturized electrochemical aptamer-based sensors on ultramicroelectrodes.
• Developed an optimized method for EABS fabrication without requiring electrode surface area enhancement.
• This approach facilitates real-time monitoring of small molecules in micro- and nanoscale systems.