Photo-controlled Hierarchical Assembly and Fusion of Coumarin-containing Polydiacetylene Vesicles

Vesicles have been a versatile topic of research in chemistry ever since the discovery that, besides phospholipids, synthetic amphiphiles can also form molecular bilayers enclosing a small aqueous compartment. Non-covalent interactions of receptors and ligands or hosts and guests at vesicle surfaces resemble recognition processes at biological membranes, including cell recognition, adhesion and fusion. Molecular recognition at membranes is often mediated by a multivalent instead of a monovalent interaction. This tutorial review describes the basics as well as the latest developments in biomimetic supramolecular chemistry of bilayer vesicles. We describe how molecular recognition can mediate the interaction between vesicles, and how the biomimetic supramolecular chemistry of vesicles furthers our understanding of biological membranes.

Four systems of nanoparticles of biodegradable polymers were developed in this research for oral delivery of anticancer drugs with Docetaxel used as a model drug, which include the poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs), the poly(lactide)-vitamin E TPGS nanoparticles (PLA-TPGS NPs), the poly(lactic-co-glycolic acid)-montmorillonite nanoparticles (PLGA/MMT NPs) and the poly(lactide)-vitamin E TPGS/montmorillonite nanoparticles (PLA-TPGS/MMT NPs). Vitamin E TPGS stands for d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS), which is a water-soluble derivative of natural vitamin E formed by esterification of vitamin E succinate with polyethylene glycol (PEG) 1000. The design was made to take advantages of TPGS in nanoparticle technology such as high emulsification effects and high drug encapsulation efficiency, and those in drug formulation such as high cellular adhesion and adsorption. MMT of similar effects is also a detoxifier, which may cure some side effects caused by the formulated drug. The drug-loaded NPs were prepared by a modified solvent extraction/evaporation method and then characterized for their MMT content, size and size distribution, surface charge and morphology, physical status and encapsulation efficiency of the drug in the NPs, and in vitro drug release profile. Cellular uptake of the coumarin 6-loaded NPs was investigated. In vitro cancer cell viability experiment showed that judged by IC(50), the PLA-TPGS/MMT NP formulation was found 2.89, 3.98, 2.12-fold more effective and the PLA-TPGS NP formulation could be 1.774, 2.58, 1.58-fold more effective than the Taxotere((R)) after 24, 48, 72h treatment, respectively. In vivo PK experiment with SD rats showed that oral administration of the PLA-TPGS/MMT NP formulation and the PLA-TPGS NP formulation could achieve 26.4 and 20.6 times longer half-life respectively than i.v. administration of Taxotere((R)) at the same 10mg/kg dose. One dose oral administration of the NP formulations could realize almost 3 week sustained chemotherapy in comparison of 22h of i.v. administration of Taxotere((R)). The oral bioavailability can be enhanced from 3.59% for Taxotere((R)) to 78% for the PLA-TPGS/MMT NP formulation and 91% for the PLA-TPGS NP formulation respectively. Oral chemotherapy by nanoparticles of biodegradable polymers is feasible.