Aptagel Plasmonic Fiber Optic Biosensor for In Vivo Continuous Drug Monitoring

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Pharmacology

Background:

• Continuous drug monitoring in living tissue, especially the brain, is challenging due to the blood-brain barrier.
• Existing methods often lack real-time capabilities or require invasive procedures.
• Developing stable, sensitive biosensors for deep tissue applications is crucial for pharmacokinetic studies.

Purpose of the Study:

• To develop and validate an implantable fiber optic surface plasmon resonance (FO-SPR) biosensor for continuous, label-free monitoring of vancomycin in brain tissue.
• To demonstrate the sensor's stability and sensitivity in vitro and in vivo.
• To establish a proof-of-concept for optical pharmacokinetic monitoring in deep tissues.

Main Methods:

• An implantable FO-SPR biosensor coated with aptagel (a split-aptamer-crosslinked hydrogel) was fabricated.
• The sensor was miniaturized for cortical implantation (3 mm length, 300 μm diameter).
• In vitro testing was performed in various biological media, followed by in vivo implantation in rat cortex for vancomycin administration and monitoring.

Main Results:

• The FO-SPR aptagel biosensor demonstrated reversible, label-free detection of vancomycin with high sensitivity (>2000 nm/RIU).
• In vitro detection limits ranged from 1.7-2.5 μM in diverse biological media, including serum.
• The sensor successfully recorded time-resolved drug dynamics in rat cortex after intravenous vancomycin administration, showing absorption and clearance phases.

Conclusions:

• This study presents the first demonstration of plasmonic fiber-based monitoring of a small-molecule drug directly within brain tissue.
• The developed FO-SPR biosensor platform is suitable for continuous optical monitoring in deep tissues.
• The technology holds significant potential for advancing in vivo pharmacokinetic applications and drug development.