The shape effect of PEGylated mesoporous silica nanoparticles on cellular uptake pathway in Hela cells

The shape of nanoparticles plays an important role in the interaction between cells and particles. However, the shape effect of mesoporous silica nanoparticles on the cellular uptake pathway and mechanism has not been reported. Herein, three different kinds of fluorescent mesoporous silica nanoparticles (FMSN, aspect ratio = 1, 2, and 4, ca. 100 nm in diameter) with similar fluorescent intensity at equivalent concentration were fabricated by a co-condensation strategy. In simulated body fluid (SBF), the PEGylated FMSN (FMSN-PEG) have higher dispersity and stability than the naked counterparts. So we chose the FMSN-PEG to research of shape effect on the cellular uptake pathway in Hela cells. We found that the uptake kinetics and pathway of three different shaped FMSN-PEG were obviously shape-dependent. The long-rod FMSN-PEG (NLR-PEG) showed higher intracellular retention amount than the short-rod FMSN-PEG (NSR-PEG) and the sphere FMSN-PEG (NS-PEG) almost over 8 h. The NSR-PEG showed the lowest intracellular amount especially with prolonged incubation time. We also found that the cellular entry pathway of NS-PEG, NSR-PEG, and NLR-PEG into Hela cells was regulated by particle shape. Spherical particles preferred to be internalized via the clathrin-mediated pathway, whereas MSN with larger aspect ratios (ARs) favored to be internalized via caveolae-mediated pathway, which could explain their different uptake kinetics. Our findings may provide useful information for optimizing the nano-based drug delivery and bio-imaging systems.