الفهرس 
General Introduction TheOnly 14 pages are availabe for public view
 |  | from | 250 |  |  |
| | | from | 250 | | |
Abstract
The field of targeted drug delivery systems is emerging due to the crucial need of selective transport of drugs to the tissue or organ of concern to improve the efficacy and reduce side effects. Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer that predominates in patients with underlying chronic liver diseases and cirrhosis. The concept of targeting drugs to the liver can be a suitable approach to overcome the associated problems of conventional systemic chemotherapy. This requires the combination of three components: the carrier, the targeting moiety and the therapeutic agent.
Objective: The aim of this study was to target a nutraceutical agent; ferulic acid to the liver using a biocompatible and an in vivo stable chitosan nanoparticles either passively or actively using glycyrrhizin moiety.
Methodology: Chitosan was grafted using a hydrophobic valeric group at different reaction times. The modified polymers were characterized by 1H NMR spectroscopy, FTIR spectroscopy, X-ray diffraction and differential scanning colorimetry (DSC) techniques. The fabricated NPs were assessed for particle size (PS), polydispersity index (PDI) and zeta potential (ZP). Also, NPs were incubated with the blood serum to investigate their stability. A D-optimal design was utilized to study different variables that might influence the ferulic acid-loaded valerate chitosan nanoparticles fabricated using ionic gelation method. Conjugation of valerate chitosan and ferulic acid (polymer-drug conjugate), using carbodiimide chemistry, was conducted to increase drug loading. Glycyrrhizin was attached for active targeting purpose and this was confirmed by1H NMR and ninhydrin assay. Freeze drying using trehalose was performed and sterilization of the selected formulations was implemented using gamma radiation. selected formulations were investigated for cytotoxicity by sulforhodamine B assay (SRB). In vivo biodistribution study was conducted on formulations (M1-P and M1-PG) where the radioactivity of the 125I-ferulic acid was recorded in different mice organs.
Results: The degree of substitution of the polymers was affected by the duration of the reaction. characterization of the synthesized polymers confirmed the successful substitution of chitosan by the valeric molecule. The particle size and PDI values of the plain nanoparticles decreased significantly with the increase in valeric content. The valerate chitosan naoparticles showed better serum stability.
The D-optimal design generated three statistical models for EE%, PDI and ZP responses which were significant with a good fit of data.
Drug loaded NPs exhibited an EE% ranging from 3.15% to 26.65%. The prepared formulations had a minimum particle diameter of 140.45 nm and a maximum diameter of 261.4 nm with polydispersity indices ranging from 0.140 to 0.477. The ZP varied between +3.8 mV and +15.2 mV.
Regarding the polymer-drug conjugate study, the maximum conjugation between ferulic acid and valerate chitosan NPs occurred at pH 5 reaching a value of 69.1%. Addition of poloxamer 407 (0.3%w/v) resulted in a significant reduction in particles size and zeta potential. Nanoparticles successfully decorated with glycyrrhizin (M1-PG) were spherical in shape and well dispersed and exhibited significant decrease in particle size. After 6 months storage at 4 ºC, poloxamer modified formulions (M1-P and M1-PG) showed slight change in particle size, PDI and ZP contrary to non-poloxamer treated formula (M1). M1 and M1-PG formulae showed minimal increase in particle size while M1-P succeeded in preserving its size after freeze-drying. Gamma radiation proved to be a suitable method for sterilization.
M1-PG scored the highest cytotoxicity followed by M1-P then M1. The in vivo biodistribution study showed that the liver scored the highest accumulation of the glycyrrhizin containing nanoparticles after 6 hours reaching a value of 13.34% injected dose per gram tissue (ID/g) of the total injected dose of labeled drug. Meanwhile the drug solution and glycyrrhizin free nanoparticles accumulation percent didn’t exceed 4.19% ID/g and 4.26% ID/g, respectively. It is worth noting that M1-P exhibited non-specific uptake by the liver, kidney and spleen 6 hours post injection.
Conclusion: In light of the above, a serum-stable hydrophobically modified chitosan was successfully prepared. The polymer-drug conjugate approach was beneficial in increasing drug loading. The glycyrrhizin decorated nanoparticles were efficient in delivering ferulic acid to the liver. To conclude up, glycyrrhizin decorated valerate chitosan nanoparticles is a promising platform for liver targeting with notable stability making it suitable for intravenous administration.
Keywords: valerate chitosan nanoparticles, ferulic acid, liver targeting, D-optimal design, glycyrrhizin.