Studies On Multi-functionalized Organic/inorganic Hybrid Nano-particles For Drug Delivery And Drug/gene Co-delivery

The purpose of drug delivery is to maximize therapeutic efficacy and minimize the negative side effects by delivering the therapeutics (chemotherapeutic agents, proteins, DNAs and RNAs) to particular organs, tissues and cells. Of the different drug delivery systems, nano-sized delivery systems have attracted great interest because of the convenience in administration through different routes, the possibility to achieve passive targeting when their sizes are in particular ranges, and facilitation to introduce ligands for active targeting due to the high surface/volume ratio of the nanoparticles.The research focus of this thesis has been concentrated on multi-functionalized organic/inorganic hybrid nanoparticles for drug delivery and drug/gene co-delivery.In Chapter1, the recent research progress in drug controlled release technique nano-sized drug delivery systems is reviewed, with the emphasis on targeting delivery systems and stimuli-responsive delivery systems.In Chapter2, we reported a facile method to prepare inorganic/organic hybrid heparin/CaCO3/CaP (HP/CaCO3/CaP) nanoparticles for drug delivery was developed. The HP/CaCO3/CaP nanoparticles were prepared by the co-precipitation of Ca2+ions with carbonate and phosphate ions in the presence of heparin. The effects of ion concentrations on the particle size and properties of the nanoparticles were investigated. The dynamic light scattering (DLS) particle size analysis and scanning electron microscopy (SEM) observation showed that the mean size of the hybrid nanoparticles could be controlled at less than50nm in the dried state through adjusting the concentrations of the inorganic ions. Fourier transform infrared (FTIR) spectroscopy indicated that the crystallization of CaCO3could be suppressed with the presence of phosphate ions in the co-precipitation system. X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) showed that the heparin content in HP/CaCO3/CaP hybrid nanoparticles decreased with the increasing ion concentrations during the nanoparticle preparation. The drug loading and release properties of the hybrid nanoparticles with different sizes and different compositions were studied. The in vitro cellular cytotoxicity indicated that blank hybrid nanoparticles had good biocompatibility, whereas doxorubicin hydrochloride (DOX) loaded nanoparticles exhibited a strong cell inhibition effect, indicating that the HP/CaCO3/CaP hybrid nanoparticles could be promising carriers for drug delivery.In Chapter3, heparin-biotin/heparin/CaCO3/CaP/DNA/DOX (HPB/HP/CaCO3/CaP/DNA/DOX) hybrid nanoparticles for co-delivery of therapeutic gene (p53plasmid) and antitumor drug (DOX) were prepared. For comparison, HPB/HP/CaCO3/CaP/DNA hybrid nanoparticles and HPB/HP/CaCO3/CaP/DOX hybrid nanoparticles were also fabricated. The cell inhibition effects of these nanoparticles on Hela cells were evaluated by MTT assay. The in vitro study showed that HPB/HP/CaCO3/CaP/DNA/DOX nanoparticles showed a strong cell inhibition effect, indicating that HPB/HP/CaCO3/CaP/DNA/DOX hybrid nanoparticles could effectively mediate gene transfection and deliver the drug to the Hela cells. Compared with the drug and gene co-delivery system (HPB/HP/CaCO3/CaP/DNA/DOX), the treatments by gene delivery system (HPB/HP/CaCO3/CaP/DNA) and drug delivery system (HPB/HP/CaCO3/CaP/DOX) separately led to much lower cell inhibition rates.In Chapter4, cell penetrating peptide (KALA) decorated hybrid nanoparticles, KALA/heparin-biotin/heparin/chitosan/CaCO3(KALA/HPB/HP/CTS/CaCO3), with pH sensitivity, active targeting property and cell penetrating ability were prepared. All the functional components were introduced to the nanoparticles by self-assembly. The usage of the hybrid nanoparticles as an anti-cancer drug delivery platform was investigated. For comparison, HP/CTS, HP/CTS/CaCO3and HPB/HP/CTS/CaCO3hybrid nanoparticles were also prepared. The size and size distribution of the nanoparticles were determined by DLS. The structure and morphology of the nanoparticles were characterized by XPS, TEM, FTIR and TGA. DOX was loaded in the hybrid nanoparticles and the in vitro release study showed that the CaCO3containing nanoparticles exhibited pH sensitive release behavior and could efficiently sustain the drug release. In vitro cellular cytotoxicity indicated the blank hybrid nanoparticles had good biocompatibility. DOX loaded KALA/HPB/HP/CTS/CaCO3hybrid nanoparticles exhibited the strongest cell inhibition effect as compared with free DOX and other DOX loaded nanoparticles because of the enhanced cell uptake caused by the cell penetrating peptide and the biotin moiety in the nanoparticles. All those results indicated that KALA/HPB/HP/CTS/CaCO3hybrid nanoparticles could be promising carriers for drug delivery.Based on our previous studies on HPB/HP/CTS/CaCO3nanoparticles, we found that HPB/HP/CTS/CaCO3nanoparticles exhibited a good stability and pH sensitivity. So we further studied the drug and gene co-delivery efficiency of these nanoparticles. In Chapter5, HPB/HP/CTS/CaCO3/DNA/DOX hybrid nanoparticles loaded with therapeutic gene (p53plasmid) and antitumor drug (DOX) were fabricated by co-precipitation. The results showed that DOX and p53plasmid could be effectively encapsulated in the hybrid nanoparticles. In vitro cell cytotoxicity study by MTT assay showed that HPB/HP/CTS/CaCO3/DNA/DOX hybrid nanoparticles had the strongest cell growth inhibition effect to Hela cells, which was caused by the synergistic effect of DNA and DOX. The presence of p53plasmid can enhance the chemosensitivity of the tumor cells to DOX, and leading to cell apoptosis.