ABSTRACT
Effective cancer chemotherapy is usually obstructed mainly by low selectivity of
the anticancer drugs towards the cancer cells. Also, not only do the anticancer
drugs affect the cancer cells, but the normal cells as well, which cause severe
side effects. Targeted drug delivery systems thus are preferred, which have been
studied extensively in the past years [1-3]. Drug-loaded nanoparticles (NPs) of
biodegradable polymers have great potential to provide an ideal solution for
most of major problems encountered in chemotherapy and those of targeting
function have become a focus in this area, which can be realized by “decorating”
the NP surface with specific ligands that can recognize the cancer cells and
mediate the ligand-receptor interaction between the decorated NPs and the
cancer cells [4]. For instance, it has been found that folate-receptor is over-
expressed on the membrane of brain, kidney, breast, ovary and lung cancer cells,
while it is absent from most normal cells instead [2, 5]. Folic acid (FOL), an
oxidized form of folate, has thus widely been used as a targeting ligand due to its
high binding affinity for the folate receptors (K d ∼10−10M) [6]. In the literature, folate decorated liposomes, micelles and NPs of biodegradable polymers such as
DSPE-PEG, PCL-MEPG, poly(lactide-co-glycolide) (PLGA)-PEG (PLGA-PEG), PLGA
have been found to increase the cellular uptake and cell cytotoxicity of the
formulated anticancer drugs [2, 7-11].
