The dependence of the fluorescence intensity of proteins on their concentrations. Fluorescence intensity (F) at 350 nm in the calibration solutions [L]0 (solid squares) and in the supernatants obtained after centrifugation of the conjugates with gold nanoparticles (open circles). Graphs (A,B) are for bovine serum albumin (BSA) (average of six repetitions); (C,D) are for Kunitz-type soybean trypsin inhibitor (STI) (average of three repetitions); (E,F) are for recombinant streptococcal protein G (protein G) (average of three repetitions); and (G,H) are for human immunoglobulin G (IgG) (average of three repetitions). Graphs B, D, F, H show the initial parts of graphs A, C, E, G.