The Effect of Nanoparticle Size on Cellular Binding Probability

Nanoparticle-based contrast agents are expected to play a major role in the future of molecular imaging due to their many advantages over the conventional contrast agents. These advantages include prolonged blood circulation time, controlled biological clearance pathways, and specific molecular targeting capabilities. Recent studies have provided strong evidence that molecularly targeted nanoparticles can home selectively onto tumors and thereby increase the local accumulation of nanoparticles in tumor sites. However, there are almost no reports regarding the number of nanoparticles that bind per cell, which is a key factor that determines the diagnostic efficiency and sensitivity of the overall molecular imaging techniques. Hence, in this research we have quantitatively investigated the effect of the size of the nanoparticle on its binding probability and on the total amount of material that can selectively target tumors, at a single cell level. We found that 90 nm GNPs is the optimal size for cell targeting in terms of maximal Au mass and surface area per single cancer cell. This finding should accelerate the development of general design principles for the optimal nanoparticle to be used as a targeted imaging contrast agent.