Tethered Split-Aptamer Biosensor for Plasmon-Enhanced Fluorescence-Based Continuous Monitoring of Vancomycin.

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Molecular Diagnostics

Background:

• Continuous monitoring of low-molecular-weight analytes is crucial for diagnostics.
• Existing methods may lack sensitivity or real-time capabilities.
• Split aptamer assays offer a versatile platform for molecular recognition.

Purpose of the Study:

• To develop a split aptamer assay with plasmon-enhanced fluorescence for continuous analyte monitoring.
• To demonstrate the tunability of assay characteristics by controlling surface concentrations.
• To validate the sensor's performance for detecting the antibiotic vancomycin.

Main Methods:

• Utilized a biointerface with split aptamer segments (S1 and S2) on a metal sensor surface.
• Employed a DNA-based flexible polymer linker (FPL) to anchor S1 and a fluorophore.
• Modulated analyte-induced distance changes between the surface and fluorophore to alter fluorescence intensity via plasmonic effects.

Main Results:

• The assay demonstrated tunable affinity interactions, varying the dissociation constant for vancomycin over two orders of magnitude (nM to μM).
• Achieved a tunable limit of detection in the low nM range, suitable for continuous monitoring.
• Showcased the ability to modulate key assay characteristics by controlling surface concentrations.

Conclusions:

• The developed split aptamer assay provides a sensitive and adaptable platform for continuous analyte monitoring.
• The plasmon-enhanced fluorescence readout enables precise control over assay performance.
• This approach is readily adaptable for various analytes utilizing reversible affinity interactions with surface-confined split aptamers.