3.3. GNPs-Enzyme Interaction Measurement

Enzymes (pepsin and trypsin) were dissolved in corresponding solution (HCl and NaCl with pH = 1.2 for pepsin and KH₂PO₄ and NaOH with pH = 7.0 for trypsin). GNPs were added into the pepsin solution to 0.5 mg/mL (the same with the concentration in cell assays). After centrifuged at 7000× g and the supernatant was discarded, the GNPs were added into trypsin solution. The aggregations of GNPs were measured and determined by UV-Vis spectrometer.