Figure 1.
Dual nanoparticle magnetic separation scheme. AuNPs coated with biotinylated diblock copolymers bind to streptavidin spiked into 50% human plasma. mNPs coated with homo-pNIPAAm are added, and the temperature is raised above the polymer LCST. Mixed streptavidin-AuNP/mNP aggregates are separated by a magnet. The separated aggregates with gold-labeled target protein are resuspended into a smaller volume of buffer below the LCST, and flowed through an LFIA strip with immobilized capture antibodies. Visualization of the target protein is achieved by AuNP light extinction at the capture line of the LFIA strip, while the non-biofunctional mNPs are rinsed away.