Plasmonic Coupling on an Optical Microfiber Surface: Enabling Single-Molecule and Noninvasive Dopamine Detection.

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• Optical fibers offer potential for biosensing in point-of-care devices due to reduced molecular interference.
• Current limitations in optical biosensor sensitivity hinder real-world applications, particularly for small-molecule detection.

Purpose of the Study:

• To develop a highly sensitive optical microfiber biosensor for dopamine (DA) detection.
• To overcome the sensitivity limitations of optical devices for single-molecule detection of small molecules.

Main Methods:

• Utilized an optical microfiber biosensor incorporating a double-amplified nanointerface with plasmonic coupling sites.
• Employed DA-binding-induced aptamer conformational transitions for signal transduction.
• Implemented selective energy enhancement and signal amplification at binding sites to prevent nonspecific amplification.

Main Results:

• Achieved ultrahigh sensitivity for dopamine detection at the single-molecule level.
• Demonstrated the ability to detect single-molecule DA signals in biological fluids.
• Showcased the sensor's capacity to monitor extracellular DA levels and oxidation processes.

Conclusions:

• The developed biosensor overcomes optical device sensitivity limits for small molecule detection.
• This technology enables noninvasive early-stage diagnostics and flexible single-molecule detection.
• Aptamer modification allows for versatile detection of various small molecules and ions.