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Mesoporous solids have been widely used in various biomedical areas such as drug delivery and tumor therapy. Although deformability has been recognized as a prime important characteristic influencing cellular uptake, the synthesis of deformable mesoporous solids is still a great challenge. Herein, deformable thioether-, benzene-, and ethane-bridged hollow periodic mesoporous organosilica (HPMO) nanocapsules have successfully been synthesized for the first time by a preferential etching approach. The prepared HPMO nanocapsules possess uniform diameters (240–310 nm), high surface areas (up to 878 m 2 ·g –1 ), well-defined mesopores (2.6–3.2 nm), and large pore volumes (0.33–0.75 m 3 ·g –1 ). Most importantly, the HPMO nanocapsules simultaneously have large hollow cavities (164–270 nm), thin shell thicknesses (20–38 nm), and abundant organic moiety in the shells, which endow a lower Young’s modulus ( E Y ) of 3.95 MPa than that of solid PMO nanoparticles (251 MPa). The HPMOs with low E Y are intrinsically flexible and deformable in the solution, which has been well-characterized by liquid cell electron microscopy. More interestingly, it is found that the deformable HPMOs can easily enter into human breast cancer MCF-7 cells via a spherical-to-oval morphology change, resulting in a 26-fold enhancement in cellular uptake (43.1% cells internalized with nanocapsules versus 1.65% cells with solid counterparts). The deformable HPMO nanocapsules were further loaded with anticancer drug doxorubicin (DOX), which shows high killing effects for MCF-7 cells, demonstrating the promise for biomedical applications.
Teng et al. (Wed,) studied this question.