ABSTRACT
Nanotechnology has been extensively exploited to improve conventional cancer
therapy in the recent years [1-5]. The designed nanocarriers for achieving
precise drug delivery to cancer cells are expected to be non-cytotoxic, efficiently
load the drugs, enhance the circulation time in bloodstream, and actively target
the cancer cells [6]. The nanocarries currently under intensive investigation
can be divided into two categories in general, i.e. the lipid-based and the
polymer-based with liposomes and polymeric nanoparticle as their typical
representative respectively. Liposomes, the spherical vesicles formed by single or
multiple lipid bilayer, have been widely used due to their high biocompatibility,
favorable pharmacokinetic profile, high delivery efficiency and ease of surface
modification. In the recent years, several liposomal drug formulations have been
approved for clinical use [7]. Limitations of liposomal drug delivery, however,
include insufficient drug loading, fast drug release, and instability in storage
[8]. Nanoparticles of biodegradable polymers (NPs), featured by their small size,
acceptable biocompatibility, high drug encapsulation efficiency especially for
hydrophobic drugs, controlled drug release manner, high cellular internalization,
desired pharmacokinetics and long circulation half-life, are another prospective
platform for drug delivery [5, 6, 9]. Up till now, nanoparticle formulations of
anti-cancer drugs such as taxanes have been intensively investigated [10-13]. It
is thus ideal if any technology could be developed to combine the advantages
and overcome the disadvantages of the two types of drug nanocarriers. One
possibility is to synthesize lipid-shell and polymer-core nanoparticles (LPNPs)
as a drug delivery system. The pioneering work of such a design can be
back to 2001, when phospholipids were used as effective emulsifier, which
stays between the oil-water interface to lower the interfacial tension and thus
facilitate the formulation of colloidal nanoparticles [14]. In this work, the residue
emulsifier was confirmed to form a shell on the PLGA core nanoparticles with
paclitaxel encapsulated as a model anticancer drug. It was also concluded that
phospholipids are much more efficient emulsifiers than the traditional chemical
emulsifiers such as polyvinyl alcohol (PVA) and those of shorter saturated chains
are more appropriate for nanoparticle formulation [14].
