Engineering Inorganic Nanoemulsions/Nanoliposomes by Fluoride-Silica Chemistry for Efficient Delivery/Co-Delivery of Hydrophobic Agents

A novel drug-formulation protocol is developed to solve the delivery problem of hydrophobic drug molecules by using inorganic mesoporous silica nanocapsules (IMNCs) as an alternative to traditional organic emulsions and liposomes while preserving the advantages of inorganic materials. The unique structures of IMNCs are engineered by a novel fluoride-silica chemistry based on a structural difference-based selective etching strategy. The prepared IMNCs combine the functions of organic nanoemulsions or nanoliposomes with the properties of inorganic materials. Various spherical nanostructures can be fabricated simply by varying the synthetic parameters. The drug loading amount of a typical highly hydrophobic anticancer drug-camptothecin (CPT) in IMNCs reaches as high as 35.1 wt%. The intracellular release of CPT from carriers is demonstrated in situ. In addition, IMNCs can play the role of organic nanoliposome (multivesicular liposome) in co-encapsulating and co-delivering hydrophobic (CPT) and hydrophilic (doxorubicin, DOX) anticancer drugs simultaneously. The co-delivery of multi-drugs in the same carrier and the intracellular release of the drug combinations enables a drug delivery system with efficient enhanced chemotherapeutic effect for DOX-resistant MCF-7/ADR cancer cells. The special IMNCs-based inorganic nanoemulsion, as a proof-of-concept, can also be employed successfully to encapsulate and deliver biocompatible hydrophobic perfluorohexane (PFH) molecules for high intensity focused ultrasound (HIFU) synergistic therapy ex vivo and in vivo. Based on this novel design strategy, a wide range of inorganic material systems with similar inorganic nanoemulsion or nanoliposome functions will be developed to satisfy varied clinical requirements.