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 manyadvantages over the conventional contrast agents. These advantages include prolonged blood circulation time, controlled biologicalclearance pathways, and specific molecular targeting capabilities. Recent studies have provided strong evidence that molecularlytargeted nanoparticles can home selectively onto tumors and thereby increase the local accumulation of nanoparticles in tumorsites. However, there are almost no reports regarding the number of nanoparticles that bind per cell, which is a key factor thatdetermines the diagnostic efficiency and sensitivity of the overall molecular imaging techniques. Hence, in this research we havequantitatively investigated the effect of the size of the nanoparticle on its binding probability and on the total amount of materialthat can selectively target tumors, at a single cell level. We found that 90 nm GNPs is the optimal size for cell targeting in termsof maximal Au mass and surface area per single cancer cell. This finding should accelerate the development of general designprinciples for the optimal nanoparticle to be used as a targeted imaging contrast agent.