A fluidic device for continuous on-line inductive sensing of proteolytic cleavages

Area of Science:

• Biomedical Engineering
• Biosensor Technology
• Enzyme Activity Monitoring

Background:

• Proteases are crucial enzymes for biological processes, and their activity measurement is vital for diagnostics and industrial applications.
• Existing protease sensors often rely on expensive consumables or are limited by sample optical properties.
• Magnetic particle-based assays offer advantages for continuous sensing due to magnetic capture and optical insensitivity.

Purpose of the Study:

• To develop a simpler, cost-effective protease sensor utilizing inductive detection of magnetic particle release.
• To enable mass production of sensor components through 3D printing and printed circuit board integration.
• To demonstrate sensitive detection of protease activity with reduced non-specific binding.

Main Methods:

• A novel sensor design integrating pulse and gradiometer coils on a printed circuit board for inductive detection.
• Fabrication of fluidic chips using 3D printed molds for mass production.
• Surface functionalization with zwitterionic polymers and PEG co-polymers to minimize albumin non-specific binding.
• Layer-by-layer covalent linking of magnetic nanoparticles via cleavable peptide substrates.
• Detection of magnetic particle release using pulsed magnetic fields and inductive signal changes.

Main Results:

• Achieved a limit of detection below 1 μg of iron using pulsed magnetic fields up to 10 mT.
• Demonstrated a 7.8-fold reduction in albumin non-specific binding through surface modifications.
• Successfully detected chymotrypsin activity in the hundreds of nM range by measuring magnetic particle release.

Conclusions:

• The developed protease sensor is simpler, more cost-effective, and easier to mass-produce compared to existing technologies.
• The sensor design minimizes non-specific binding and demonstrates sensitive detection of enzymatic activity.
• This technology holds potential for disposable fluidic chips and inexpensive detection devices for ubiquitous protease monitoring.