Sequential drug release via chemical diffusion and physical barriers enabled by hollow multishelled structures

Hollow multishelled structures (HoMSs), with relatively isolated cavities and hierarchal pores in the shells, are structurally similar to cells. Functionally inspired by the different transmission forms in living cells, we studied the mass transport process in HoMSs in detail. In the present work, after introducing the antibacterial agent methylisothiazolinone (MIT) as model molecules into HoMSs, we discover three sequential release stages, i.e., burst release, sustained release and stimulus-responsive release, in one system. The triple-shelled structure can provide a long sterility period in a bacteria-rich environment that is nearly 8 times longer than that of the pure antimicrobial agent under the same conditions. More importantly, the HoMS system provides a smart responsive release mechanism that can be triggered by environmental changes. All these advantages could be attributed to chemical diffusion- and physical barrier-driven temporally-spatially ordered drug release, providing a route for the design of intelligent nanomaterials.

Platelet-derived porous nanomotor for thrombus therapy

The treatment difficulties of venous thrombosis include short half-life, low utilization, and poor penetration of drugs at thrombus site. Here, we develop one kind of mesoporous/macroporous silica/platinum nanomotors with platelet membrane (PM) modification (MMNM/PM) for sequentially targeting delivery of thrombolytic and anticoagulant drugs for thrombus treatment. Regulated by the special proteins on PM, the nanomotors target the thrombus site and then PM can be ruptured under near-infrared (NIR) irradiation to achieve desirable sequential drug release, including rapid release of thrombolytic urokinase (3 hours) and slow release of anticoagulant heparin (>20 days). Meantime, the motion ability of nanomotors under NIR irradiation can effectively promote them to penetrate deeply in thrombus site to enhance retention ratio. The in vitro and in vivo evaluation results confirm that the synergistic effect of targeting ability from PM and motion ability from nanomotors can notably enhance the thrombolysis effect in both static/dynamic thrombus and rat model.