Table 1.

The table summarizes few selected examples that we discuss in Section 2.2 of observations reported in literature on the effect of nanoparticle properties on the mechanism of uptake by cells. References to literature with supporting as well as opposing observations are included (also discussed in Section 2.2). We emphasize that the table is far from complete and includes only a few examples, selected solely to illustrate the complexity of outcomes. In fact, we consider the observations listed still as preliminary, as also illustrated by apparently contrasting results in the opposing studies included (in most cases performed using different conditions and systems).

reported observation or preliminary statement	supporting studies	opposing studies
nanoparticles uptake efficiency decreases with increasing size	[107–109]	[112]
nanoparticles up to 100 nm in diameter enter through clathrin-dependent endocytosis	[107,113]	[114–116]
non-phagocytic cells can only internalize materials up to 200 nm	[8]	[107,114]
positively charged nanoparticles are internalized more efficiently than negatively charged or neutral nanoparticles	[114,124–125,128,130]	[126–127,129]
positively charged nanoparticles enter (at least partially) through clathrin-dependent endocytosis	[21,128,130]	[129]
nano-sized objects with small aspect ratios are internalized more efficiently	[112,133–134]	[114,136]
more rigid nanoparticles enter more efficiently than softer nanoparticles	[139,141,143]	[142]