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Synergistic therapeutic effect through the intracellular co-delivery of chemotherapy and biomacromolecule drugs is a novel strategy for improving tumor treatment effectiveness. A triblock copolymer, poly(acrylic acid)-poly(N, Ndiisopropylaminoethyl methacrylate)-poly(N-vinylcaprolactam) (PAA-PDPA-PNVCL), was designed and synthesized for the construction of smart responsive drug carriers. The structure of the polymers was verified by nuclear magnetic resonance spectroscopy (¹H-NMR) and fluorescence spectrophotometer (FL). The transmittances of the polymer solutions under different pH values or temperatures were measured by ultraviolet-visible spectroscopy (UV-Vis). Results showed that the polymer had excellent pH responsiveness and a low critical solution temperature (LCST), which could self-assemble into vesicles with PAA as hydrophilic shell, PDPA as hydrophobic intermediate layer and PNVCL as hydrophilic cavity. Then, the PAA shell layer was crosslinked with disulfide bonds through amide reaction, to improve the structural stability of vesicles and meanwhile introduce the reduction sensitivity. The changes of the particle size, Zeta potential, and morphology of the vesicle under different conditions were studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Results showed that the shell-crosslinked vesicles were uniformly sized spherical structure with good pH value and reduction responsiveness. Their drug encapsulation effect and in-vitro release behavior under different pH values and glutathione (GSH) concentrations were studied by UV-Vis and FT-IR. Results showed that the carriers could achieve zoned and co-loading of hydrophobic small molecule drug (doxorubicin (DOX)) and hydrophilic macromolecular protein drug model (bovine serum protein (BSA)). The hydrophobic layer of PDPA and the crosslinked layer of PAA provided dualblockade for drug leakage. The leakage of drugs under normal physiological conditions was low, and the release of DOX and BSA could only be triggered under simulated tumor microenvironment, that is, weak acid and high concentration of GSH conditions. The smart responsive drug carriers constructed in this paper are expected to achieve co-delivery of chemotherapy and biomacromolecule drugs, which have potential application value to the clinical treatment of tumors. [ABSTRACT FROM AUTHOR]

Two novel stigmasterol derivatives as gelators are synthesized，and named as compounds 1 and 2， respectively. The structure and properties of gels are studied by scanning electron microscopy（SEM），Fourier transform infrared spectroscopy（FT-IR）and UV-Vis spectrophotometer. The results of the gelation properties of compounds 1 and 2 show that they could gelate in DMSO and methanol. Compound 1 also forms a stable gel in DMSO/water mixed solvents at a volume ratio of 9∶1，8∶2，and 7∶3，respectively. In addition，when compounds 1 and 2 are gelated at a mass concentration of 12 mg/mL in DMSO，the gel-sol phase transition temperatures（Tgel）of the two compounds are 51 and 46 ℃，respectively，indicating that the thermal stability of their gelation decreases significantly with the increase of steroidal structural units in the gelator. With the increase of steroid structural units in the gelators，the thermal stability of the gel formation decreases significantly. On this basis，the gel prepared by compound 1 is used as the carrier，and its encapsulation and release in rhodamine B and methylene blue，as well as the anticancer drug doxorubicin are studied by UV-Vis spectroscopy. The results show that the prepared gels could be used as a drug carrier，and the maximum release value reaches 84% in water at 240 min. Furthermore，this study may provide a useful idea for the preparation of stigmasterol derivative gels and its application as a drug carrier in drug delivery. [ABSTRACT FROM AUTHOR]

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