Figure 2From: The effect of nanoparticle size on the probability to cross the blood-brain barrier: an in-vitro endothelial cell model UV–vis spectroscopy of 20, 50, 70 and 110 nm GNP. Each size exhibits a peak at a different wavelength: 525, 530, 540 and 570, respectively. When the GNPs are enlarged, there is a red shift in the surface plasmon resonance (SPR) peak of the particles, from 525 nm to 570 nm.Back to article page