A) Atomic force microscope images demonstrate uniformity of the spherical poly (NIPAm/RBB) nanoparticles. B) Nanoparticle-Immulite GH assay has a within run CV = 9% (over ten replicates) and virtually 100% yield. Mean +/− CV. IS = initial solution, S = Supernatant, E = nanoparticle eluate, C100% = calculated GH concentration based on 100% yield. C) And D) Linearity of the immunoassay (9 calibrator values, range 0.750-0.05 ng/mL) with and without nanoparticle preprocessing, respectively. Nanoparticle preprocessing maintains the linearity of the immunoassay (R2=0.986, 0.982, with and without the nanoparticles, respectively).