System and method for monitoring molecular agents in vivo by estimating magnetic nanoparticle aggregation

A system for isolating magnetic nanoparticle-nanoparticle (NP-NP) binding/aggregation using coated magnetic NPs that bind selectively to at least one discrete compound associated with a biological process comprising:

• a spectrometer adapted to:
• scan a sample containing the at least one discrete compound associated with the biological process and infused with the coated magnetic NPs that bind selectively thereto;
• apply magnetic fields from at least one drive coil that varies the magnetic fields in frequency and amplitude thereacross,
• the frequency and amplitude varies independently for at least a portion of the magnetic fields causing viscosity changes in the sample to be distinguishable from bindings between coated magnetic NPs and causing non-specific bindings in the sample distinguishable from bindings between coated magnetic NPs;
• and
• receive a signal indicative of a response spectra of the sample to the frequency and amplitude variations of the magnetic fields, the signal received from a first pickup coil having an axis that is at least one of (a) inline with and (b) perpendicular to a plane of the at least one drive coil,
• wherein the response spectra includes a plurality of dimensions and the response spectra distinguishes coated magnetic NP-NP bindings from viscosity changes and from non-specific bindings;
• and
• a computing device configured for determining whether NP-NP bindings in the sample response spectra is consistent with core size distribution and hydrodynamic size distribution estimates that are based on an initial size distribution of the NPs for the sample.