pH-Responsive expandable polycarbonate–doxorubicin conjugate nanoparticles for fast intracellular drug release

Nanoparticles with tertiary amines were prepared, which are pH-responsive, expanding to expose the acid-sensitive chemical bond and accelerating drug release.

Construction and Biocompatibility of Three-Dimensional Composite Polyurethane Scaffolds in Liquid Crystal State

Liquid crystal (LC), a characteristic substance of biofilms, has been reported to positively affect cell affinity. To better combine and utilize the properties of an LC and the advantages of polyurethane (PU) elastomers, the three-dimensional printing (3DP) molding technology and the simple soaking-swelling blending technology were used to construct PU/LC 3D composite scaffolds, and the compressive strength, porosity, hydrophilicity, and in vitro cell experiments of the scaffolds were initially discussed. The results indicated that the newly developed PU/LC 3D composite scaffolds exhibited an LC state; the addition of an LC did not change the porosity after swelling while maintaining a high porosity; the compressive strength of the composite scaffolds decreased while still maintaining high mechanical properties and enhancing hydrophilicity. At the same time, it could improve the cell affinity on the surface of the material, which was beneficial to increase the cell adhesion rate and cell activity, promote the osteogenic differentiation of human mesenchymal stem cells grown on the materials, and improve the alkaline phosphatase activity, calcium nodules, and the expression of related osteogenic genes and proteins. These results demonstrated potential applications of PU/LC composite scaffolds in repairing or regeneration of bone tissue engineering.

New liquid crystal polycarbonate micelles for intracellular delivery of anticancer drugs

To construct pH/temperature dual sensitive micelles as novel drug delivery carriers, the synthesis of two diblock copolymers mPEG₁₁₃-PMCC₉-(PMCC-DBO)₂₇ and mPEG₄₃-PMCC₂₅-(PMCC-DHO)₁₅ based on mPEG and polycarbonate modified by acid and liquid crystal groups is described. In aqueous solution, mPEG₁₁₃-PMCC₉-(PMCC-DBO)₂₇ and mPEG₄₃-PMCC₂₅-(PMCC-DHO)₁₅ could self-assemble to form nanospheres and vesicles at very low critical micelle concentration, respectively. Both nanospheres and vesicles were less than 100 nm in diameter and demonstrated high loading capacity of doxorubicin (DOX) through ionic interaction between the free carboxyl groups in PMCC segments and the amine groups in DOX. In vitro release studies indicated that the two copolymer micelles were capable of pH/temperature-triggered release of doxorubicin and without a significant initial burst release. Furthermore, MTT assays showed that the blank copolymer micelles were nontoxic, while the drug-loaded micelles exhibited potent cytotoxic activity towards HeLa cells. These pH/temperature responsive copolymer micelles provided a new strategy for constructing stimuli-responsive drug delivery carriers in chemotherapy.