Construction of hollow polydopamine nanoparticle based drug sustainable release system and its application in bone regeneration

Nanomaterial-based drug sustainable release systems have been tentatively applied to bone regeneration. They, however, still face disadvantages of high toxicity, low biocompatibility, and low drug-load capacity. In view of the low toxicity and high biocompatibility of polymer nanomaterials and the excellent load capacity of hollow nanomaterials with high specific surface area, we evaluated the hollow polydopamine nanoparticles (HPDA NPs), in order to find an optimal system to effectively deliver the osteogenic drugs to improve treatment of bone defect. Data demonstrated that the HPDA NPs synthesized herein could efficiently load four types of osteogenic drugs and the drugs can effectively release from the HPDA NPs for a relatively longer time in vitro and in vivo with low toxicity and high biocompatibility. Results of qRT-PCR, ALP, and alizarin red S staining showed that drugs released from the HPDA NPs could promote osteogenic differentiation and proliferation of rat bone marrow mesenchymal stem cells (rBMSCs) in vitro. Image data from micro-CT and H&E staining showed that all four osteogenic drugs released from the HPDA NPs effectively promoted bone regeneration in the defect of tooth extraction fossa in vivo, especially tacrolimus. These results suggest that the HPDA NPs, the biodegradable hollow polymer nanoparticles with high drug load rate and sustainable release ability, have good prospect to treat the bone defect in future clinical practice.

Hollow Polypyrrole Nanospindles for Highly Effective Cancer Therapy

Polypyrrole (PPy) hollow nanostructures continue to attract the interest researchers because of their good biocompatibility, high photothermal conversion efficiency, and excellent stability. The preparation of PPy hollow nanostructures by the hard templating method without complicated post-synthetic treatment and additional oxidizing agents remains a challenge. In this work, we report a facile and novel hard templating method to fabricate hollow PPy nanospindles in which MIL-88(Fe) serves as the template. Fe³⁺ centers in MIL-88(Fe) could induce the polymerization of pyrrole to construct the shell, and MIL-88(Fe) would be decomposed by solvent water. This method did not require any extra oxidizing agents and post-synthetic treatment. Hollow PPy nanospindles exhibit excellent photothermal and drug loading ability, and the therapy effect of cancer was significant. This method provides a new hard templating approach for the synthesis of polymer hollow nanostructures.