Several factors can influence the effectiveness of the EPR effect. These include the size, shape, and surface properties of the nanoparticles, as well as the physiology of the tumor. Generally, nanoparticles in the size range of 10-200 nm show optimal accumulation. Surface modification, such as PEGylation, can improve circulation time and reduce recognition by the immune system, enhancing the EPR effect. Tumor heterogeneity and the extent of vascularization also play critical roles in determining the degree of EPR effect.
