Molecular design of layer-by-layer functionalized liposomes for oral drug delivery.

Liposomes are small spherical vesicles composed mainly of phospholipids and cholesterol. Over the years, a number of liposomal formulations have shown clinical promise, but the use of liposomes in oral drug delivery is still limited. This is partly due to the vulnerability of conventional liposomes to the detrimental effect of gastrointestinal destabilizing factors and also to the poor efficiency in intestinal absorption of liposomes. Some of these issues can be ameliorated using the layer-by-layer (LbL) assembly technology, which has been widely applied in surface modification of various nanoparticulate systems. Discussions on LbL functionalization of liposomes as oral drug carriers, however, are scant in the literature. To fill this gap, this article presents an overview of the roles of LbL functionalization in the development of liposomes, followed by a discussion of major principles of molecular design and engineering of LbL-functionalized liposomes for oral drug delivery. Regarding the versatility offered by LbL assembly, it is anticipated that LbL-functionalized liposomes may emerge as one of the important carriers for oral drug administration in the future.