A Magnetic Nanoparticle-Based Immunoassay Using a Microfluidic Device

Take a microfluidic device affixed to a microscope stage, comprising an inlet for dispensing reagents, interconnected channels for fluid flow, and outlets for purging the fluids.

The main channel contains a central staggered restriction with trapped aggregated iron microparticles.

The channels are incubated with a blocking solution to prevent non-specific antibody binding.

Flow a wash buffer, removing excess blocking solution.

Introduce an immunocomplex suspension at a defined flow rate. The immunocomplex consists of magnetic nanoparticles, coated with antigens bound to primary antibodies, which are further bound to peroxidase-conjugated secondary antibodies.

Apply an external magnetic field, magnetizing the aggregated microparticles and transforming them into a magnetic trap for capturing the immunocomplexes.

Introduce a fluorogenic substrate that is converted by the peroxidase into a fluorescent product and flows through the trap.

Using the microscope, compare the fluorescence before and after the trap, confirming the capture of immunocomplexes.