The present disclosure utilizes the aggregation of stimuli-responsive polymers to isolate a diagnostic target (e.g., an antigen) from a solution using magnetophoresis. Isolating the diagnostic target provides a route to identify the presence of the diagnostic target in the solution.

Disclosed are systems, methods, and computer software for determining a conformational change in a structure of a protein. One method includes delivering a magnetic nanoparticle-nanobody (MNP-NB) complex to a sample containing a protein, where the MNP-NB complex will bind to the protein in the sample. An external magnetic field is applied to the sample with a magnetic field generation system. Signals are detected from the MNP-NB complex that reflect a response to the external magnetic field and a conformational change in a structure of the protein in the sample is determined from the signals.