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Encapsulation and release of water-insoluble drugs has been a challenge. In this paper, a pH/glutathione (GSH) dual-responsive self-assembly based on graphene oxide (GO) was designed and fabricated for the effective delivery of the anti-cancer drug, quercetin (QU). The pH-sensitive poly(2-(diisopropylamino ethylmethacrylate) (PDPA) was synthesized and grafted onto GOvia a disulfide bond (GO–PDPA). Then, the hydrophobic QU was loaded onto GO–PDPA followed by coating with chitosan (CHI) to obtain a biological medium-stable GO-based self-assembly (GO–PDPA–CHI). Dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) were used to investigate their size and zeta-potential, morphology, and chemical structures. The coating of chitosan on GO–PDPA not only increased the pH sensitivity of the carrier but also reduced its drug leakage from 60% to 40% at a pH of 7.4. Drug release experiments also showed that under the stimulus of pH and GSH, the drug cumulative release amount was over 75%. The dual-sensitive GO-based self-assembly exhibits great potential as a drug carrier for hydrophobic drugs in cancer therapy. [ABSTRACT FROM AUTHOR]

Due to the difference of the intracellular microenvironment between tumor and normal cells, many stimuli-responsive drug carriers have been developed for precise drug delivery and improved treatment effect. In this paper, a multi responsive drug delivery system based on mesoporous silica nanoparticle (MSN) was prepared. A pH/ROS-sensitive polymer was designed and used to attach to the MSN surface, which acted as a smart nano-valve to prevent premature leakage of drugs. The carrier has been proved to release drugs selectively in simulated tumor microenvironment with lower pH and higher ROS content. And, by co-loading a photosensitizer with antitumor drug, the carrier could produce exogenous ROS under the near-infrared light irradiation, resulting in much quicker removing of the polymer and more drug release. Furtherly, the antitumor effect was evaluated by CCK-8 assay using normal and tumor liver cells. In short, the results of drug release and cell experiments both showed that the carriers had excellent anti-tumor cells effects. [Display omitted] [ABSTRACT FROM AUTHOR]

• Design of microgel with double security function. • pH/redox/US multi-controllable drug release of microgel. • Achievement of quick and complete drug release. In this paper, the multi-responsive core-shell microgels were prepared for constructing a double-locked drug delivery system. The pH- sensitive poly(2-(diisopropylamino ethylmethacry-late)-block-poly(ethyleneimine) diblock copolymers (PDPA-b-PEI) were synthesized and used to prepare micelles through their self-assembly in neutral solution. Redox-responsive gel shells were formed by Michael addition of primary amine group of branched PEI using disulfide as a cross-linker, which was specifically cleaved by glutathione (GSH). Anticancer drug doxorubicin DOX and perfluorohexane (PFH) could be encapsulated in the core of microgel. The DOX was released sustainably only under the condition of pH and GSH were both right. For example, under neutral condition with GSH, DOX could not release swimmingly due to the core of microgels was in hydrophobic state and wrapped the DOX firmly, although the gel shells were collapsed by GSH. When exposed to ultrasound, the drug released abruptly and achieved a complete release instantly. Moreover, it was found that the structure of the microgels was not destroyed after the ultrasound stimulus but had undergone an expansion-recovery process. Finally, it was demonstrated that the microgel had a "double security" effect, ensuring the low drug leakage during the normal blood circulation and efficient drug release under the pH/redox/ultrasound stimulus. The multi-responsive microgels designed here, which combines the usage of both endogenous and exogenous stimuli, has the advantages of low side-effect, high spatiotemporal controllability and complete release. [ABSTRACT FROM AUTHOR]