Figure 2

PEG-coated and uncoated 23 nm gold nanoparticle behavior in simulated gastric fluid. Dynamic light scattering was used to show the agglomeration behavior of PEG-coated and uncoated 23 nm gold nanoparticles in simulated gastric fluid during 2 hours of incubation at 37°C. Figure 2 A shows both particle types over the 2 hour time course; uncoated gold nanoparticles agglomerate immediately while PEG-coated particles remain well dispersed in simulated gastric fluid. Figure 2 B shows photographs of PEG-coated and uncoated gold particles in water and in simulated gastric fluid after 5 minutes, 2 hour and 24 hours. As seen using DLS, PEG-coated particles remain well dispersed and appear as they do in water while uncoated particles agglomerate extensively. The particle size distributions for the particles in water and in SGF at 5 minutes and 2 hours are also shown for PEG-coated (Figure 2 C) and uncoated particles (Figure 2 D).