Fig. 4

a Determining the ideal size of GNP. Among 10, 15, and 80 nm, 15 and 80 nm showed similar results. Fifteen nanometers was used to determine the limit of detection with FIX. b A control experiment for the detection of FIX. Three different control experiments (C1—without FIX antibody; C2—without anti-mouse IgG; C3—without FIX) were conducted. No significant signal was found in any of the control experiments. Figure insets display the visual results