br The morphology of MSNs was
The morphology of MSNs was characterized by TEM. As shown in Fig. 1A, MSNs presented a uniform size around 100 nm, a spherical shape, a well particle monodispersity, as well as an obvious mesoporous structure. For DOX/[email protected], a clear thin layer surrounded MSNs in Fig. 1B demonstrated the successful capping of CaCO3 as gate-keeper. Meanwhile, this figure revealed that DOX loading had no obvious
influence on the morphology of the MSNs, as nearly the same mor-phology, size distribution and dispersity in comparison with the bare MSNs. Meanwhile, DLS results (Fig. 1 C) also demonstrate the negli-gible change of size distribution after DOX loading. UV–vis spectra were used to confirm the DOX loading into MSNs. As shown in Fig. 1D, the characteristic Haloperidol peak located at 480 nm could be also observed in the absorption curves of DOX/MSN and DOX/[email protected], while MSN and [email protected] didn’t exhibit this absorption peak. In addition, the N2adsorption-desorption isotherms curves of MSN and DOX/MSN were also recorded to verify the loading of DOX into MSNs (Fig. 1E and 1 F), as the BET surface area decreased from 1542 m2/g to 1046 m2/g. To improve the stability of DOX/[email protected], the cell membrane fragments (CM) was adsorbed onto these nanoparticles. TEM revealed the successful coating of CM layer on the surface and the well-disper-sion of obtained DOX/[email protected]@CM (Fig. 2A). The intermediates at each step and the final product of DOX/[email protected]@CM were characterized by fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). As shown in Figure S1, the FT-IR spectra of DOX/MSN showed both the typical peaks at 1578 cm−1 (assigned to C]O stretching vibration of DOX) and 1093 cm−1 (as-signed to the Si-O-Si bond stretching of MSN). Compared with DOX/ MSN, a new peak around 1420 cm−1 was found in the spectrum of DOX/[email protected], which is mainly resulted from carbonate vibration of CaCO3. After further coated with cancer cell membranes (CM), the PO43- (from phospholipid molecules in CM) characteristic absorption located at 1257 cm−1 appeared in the spectrum of DOX/[email protected]@CM. Furthermore, compared with other intermediates, the final product of DOX/[email protected]@CM showed most significant weight loss at high temperature (Figure S2). These results confirmed the suc-cessful preparation of DOX/[email protected]@CM. In order to further verify the coating layer is resulted from the LNCaP-AI cells, the protein ingredient of DOX/[email protected]@CM was analysed by using gel elec-trophoresis. As shown in Fig. 2B, DOX/[email protected]@CM showed the same electrophoresis patterns as cancer cell lysate and cancer cell membrane. Furthermore, western blot analysis also demonstrated the well retention of the membrane proteins on our nanoparticles, as the specific marker of claudin-1 belonging to the membrane proteins also appeared in the pattern of DOX/[email protected]@CM in comparison with
Fig. 2. Characterization of DOX/
[email protected]@CM. (A) TEM of DOX/ [email protected]@CM. (B) SDS-PAGE analysis of cell lysate (i), cell membrane (ii), and DOX/ [email protected]@CM (iii). Samples were stained with Coomassie blue. (C) Western blot analysis of membrane-specific protein (claudin-1) in cell lysate (i), cell membrane (ii), and DOX/ [email protected]@CM (iii). (D, E) Size distribu-tion of DOX/[email protected] (D) and DOX/ [email protected]@CM (E) in water or PBS with 10% FBS measured by DLS (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article).
the source of cancer cell lysate and cancer cell membrane (Fig. 2C). The zeta potential of DOX/[email protected] was determined to be -9.6 mV. After further cloaked with the negative charged cell membrane, the zeta potential of these nanoparticles further decreased to -19.8 mV (Figure S3). Furthermore, to demonstrate the enhanced colloid stability of na-noparticles after CM cloaking, the hydrodynamic sizes of DOX/ [email protected] and DOX/[email protected]@CM in water or mimic physio-logical environment (PBS + 10% FBS) were measured by dynamic light scanning (DLS). As shown in Fig. 2D and E, the size of DOX/ [email protected] dramatically increased from 130.6 nm (in water) to 942.1 nm (in PBS + 10% FBS), while the diameter of DOX/[email protected]@CM only slightly increased from 154.1 nm to 160.1 nm. Mean-while, no significant aggregation or obvious size alteration of DOX/ [email protected]@CM was observed during storage in RPMI-1640 medium even for 8 days (Figure S4). These results indicated that DOX/ [email protected]@CM have good stability for biological application.