Development of self-assembled nanoparticles (NPs) can be considered to target specific cancer therapy and gene delivery. Currently, self-assembled nanoparticles of layer-by-layer structure with targeting properties have been applied for therapy and gene delivery. In this thesis, PLGA (poly lactic-co-glycolic acid) based cationic nanoparticles with PEI (polyethyleneimine) were prepared by electrostatic interaction and HA (hyaluronic acid)-Zein nanogels (NGs) were further developed to deliver pH1N1 DNA vaccine, CRC (curcumin) anticancer agents or Akt-1 siRNA.
In chapter 2, intradermal pH1N1 DNA vaccine delivery platform using microneedles coated PLGA/PEI nanoparticles was prepared to enhance humoral immune response. The hydrophilicity of the stainless steel MNs was enhanced by immobilizing the MN surface by silanization to improve the coating efficiency. MNs coated with the polyplex encapsulating DNA vaccine were prepared by optimizing the 6:1 N/P ratio which showed the highest transfection efficiency in mammalian cells. They were well coated onto the MNs without severe aggregation of the polyplex at drying forms. The coated polyplex rapidly dissolved in porcine skin within 5 min. and induced a higher humoral immune response than that of intramuscular polyplex delivery and naked pH1N1 DNA vaccine delivery by a microneedle. These results show that the delivery of intradermal DNA vaccines with cationic polyplex coated MNs has potential in skin immunization of DNA vaccine.
In chapter 3, we developed novel hyaluronic acid cross-linked zein nanogels (HA-Zein NGs) to deliver the potential anticancer agent curcumin, a naturally occurring phytochemical drug. In vitro studies to analyze their size, stability and cytocompatibility showed that they are highly compatible with the tested cell lines. The in vitro studies of the CD44+ve CT26 cell line clearly showed that the HA-Zein NGs are selectively taken up by more than by the preinhibited CD44 receptor CT26 cells. The curcumin encapsulated HA-zein NGs (HA-Zein-CRC NGs) were found to exert a specific toxicity against CT26 sparing healthy normal fibroblast cells in vitro. The apoptotic effects were further confirmed with flow cytometry showing that the HA-Zein-CRC NGs exhibit a high anticancer activity against the CT26 cells. The in vitro stability tests in serum showed they are highly stable compared to non-cross-linked Zein NGs. The in vivo biodistribution with a CT26 tumor model showed their high circulation and consequently improved antitumor efficacy with a reduced amount of CRC, which is significant compared to a previous report. Thus, the preclinical studies clearly show that these novel HA-Zein NGs would be highly beneficial in encapsulating hydrophobic drugs and improving the pharmacokinetics of the encapsulated drugs thereby enhancing the therapeutic outcomes.
In chapter 4, PLGA/ssPEI/HA triple layered nanoparticles (TLNPs) were prepared for co-delivery CRC and Akt-1 siRNA to enhance anticancer efficiency. PLGA/PEI double-layered nanoparticles have been reported as effective non-viral vectors for gene delivery to enhance cell viability and transfection efficiency. However, bPEI(25kDa) was not able to remove from animal body because they have high molecular weight compared to renal filter and cause cell toxicity via high positive surface charge density. Therefore, disulfide bond crosslinked PEI (ssPEI) has been considered alternatives against bPEI(25kDa). CRC and Akt-1 siRNA were able to be loaded in TLNPs and particle characterization was conducted to confirm specific targeting ability and stimulus-responsive drug release of TLNPs.