Table 1.

Properties-dependent clearance of nanocarriers (NCs).

	Biodistribution Profiles in Clearance Organs
SIZE	Renal excretion is particularly relevant for NCs below the threshold value (ca. 5.5 nm) [25]. MPS clearance is operated by liver>spleen>lung phagocytes. However, the spleen and lung fraction increase with the particle size: NCs > 150 nm are more prone to splenic filtration, while lung accumulation is particularly promoted when the NCs size is close to the micromillimeter range, or they aggregate [26,27].
SURFACE CHARGE	It is generally accepted that positively charged NCs are more rapidly sequestered by MPS than negative and neutral NCs due to the highly-dense coating of serum proteins formed on the administration [27]. However, the surface hydrophobicity, as well as the charge density, strongly influences the elimination rate [28].
SHAPE	NCs’ shape determines the movement in blood circulation and the organ-specific biodistribution [25]. Spherical NCs presented the longest circulation time, while rod-, disc-, cage- particles exhibited an increased splenic and hepatic accumulation compared with spherical counterparts [29].
STIFFNESS	Due to the intrinsic deformability, soft NCs have prolonged circulation lifetimes and reduced splenic accumulation when compared with rigid NCs [30].