Multiwall carbon nanotubes (MWCNTs) are often used to modify polymer membranes as additives, however, MWCNTs are easy to agglomerate and entangle in polymer matrix due to their own strong van der Waals force. MWCNTs were doubly modified by bonding octadecylamine (ODA) and SiO2 through the respective amidation and esterification reactions to prepare SiO2-MWCNT-ODA nanocomposites. The amino groups on ODA were amidated with the carboxyl groups on MWCNT-COOH. Then the hydroxyl groups on SiO2 were bonded to MWCNT-COOH through esterification to obtain SiO2-MWCNT-ODA nanocomposites. PES/SiO2-MWCNT-ODA composite ultrafiltration (UF) membrane was prepared by non-solvent induced phase separation (NIPS) method. SiO2-MWCNT-ODA nanocomposites and PES/SiO2-MWCNT-ODA membrane were characterized by FTIR, XRD, TGA, and SEM, etc. The results showed that PES/SiO2-MWCNT-ODA membrane had significantly improved permeability, rejection, and antifouling properties for comparison with PES membrane. The pure water flux of PES/Nano.2-0.5 reached 212.5 L m−2 h−1, which was approximately 2.6 times than that of PES membrane, and the rejection of BSA protein for composite membrane was as high as 94.2%. PES/SiO2-MWCNT-ODA composite membrane had excellent antifouling performance and the flux recovery rate (FRR) of PES/Nano.2-0.5 membrane could still maintain at higher value of 84.82% after two cycles in the antifouling test.
Due to significant pH difference among the healthy tissue, tumor tissue as well as intracellular endo/lysosome, constructing pH‐responsive biodegradable nanodrug delivery systems has received more and more attention. Herein, double‐end alkenylated acetal monomer (based on cinnamaldehyde (CA)) and double‐end sulfhydrylation Schiff base monomer were designed and synthesized, and three pH‐responsive biodegradable block copolymer mPEG‐b‐poly(Schiff base‐acetal) (P1), mPEG‐b‐poly(acetal) (P2), and mPEG‐b‐poly(Schiff base) (P3) were obtained by Michael addition reaction. All these polymers could be self‐assembled with gemcitabine (GEM) to form GEM‐loaded micelles. Proton nuclear magnetic resonance (1H NMR) and dynamic light scattering (DLS) experiments proved that these polymer micelles have good pH responsiveness. The size and morphology of both blank and GEM‐loaded micelles were characterized by DLS and scanning electron microscope (SEM). The GEM/P1, GEM/P2, and GEM/P3 micelles exhibited pH‐sensitive drug release properties and the GEM/P1 micelles has the relatively fastest drug release rate. Containing multiple acetal and Schiff base moieties GEM/P1 micelles showed fastest cellular internalized rate and best in vitro antitumor activity among all GEM‐loaded micelles.
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