To a 200 µL solution of 40 nm GNPs coated with copoly azide positive 4% (prepared as described in Section 2.8) 30 µL of 2 mg/mL DBCO-modified streptavidin, 70 µL of MQ water and 0.2 µL of Tween 20 were added and the obtained solution was incubated overnight at 25°C under stirring. After the incubation, the sample was centrifuged for 2 minutes at 10,000 x g, the supernatant was removed, and GNPs resuspended in 300 µL of 0.1X PBS + 0.05% Tween 20. Centrifugation was repeated three times to wash GNPs.