Preference toward nonspecific interaction before his-tag—Ni-NTA interaction demonstrated through increasing ratios of 6×His-rmES protein (μg) to bis-Ni-NTA nanoparticle (mg) A: 10.2, B: 15.3, C: 61.3. (M = Marker, FT = Flow Through, W1 = Wash 1, W2= Wash 2, Wash 3 = W3, E1 = Elution 1, E2 = Elution 2, NP = protein bound nonspecifically to nanoparticle.)