Structural Design And Functionalization Of Bovine Serum Albumin Nanoparticles Based On Layer-by-layer Assembly

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in China, and general anti-cancer drugs have many drawbacks, such as lackness of targeting tumor cells, high cytotoxicity, and many side effects. It is necessary to develop a drug delivery system (DDS) with targeted ability and stimuli-responsive behavior. Drug controlled delivery systems based on polymeric biodegradable nanoparticles (NPs) are mostly investigated because of the submicro size and ease of targeting. Biodegradable and nontoxic bovine serum albumin (BSA) is one of the commonly used natural polymers for drug delivery. In this thesis, bare BSA NPs were prepared via a desolvation-crosslinking method. By layer-by-layer self-assembly (LBL), the surface of the nanoparticles was coated with polyelectrolyte multilayers and functional polyelectrolytes grafting with PEG or targeting ligand for prolonged circulation or targeting delivery. Release and targeting properties and hemocompatibility of the multilayers covered and aptamer decorated nanoparticles were invastigeted in vitro and preliminary in vivo.Firstly, after the bare BSA NPs were fabricated by a desolvation-crosslinking method, poly(allylamine hydrochloride)(PAH)/poly(sodium4-styrene sulfonate)(PSS) multilayers and poly(allylamine hydrochloride)-graft-poly(ethylene glycol)(PAH-g-PEG) with different grafting ratios were coated on the surface of bare BSA NPs. The influence of the multilayers and PAH-g-PEG coating on stability of bare BSA NPs and loading and release of anticancer drug were assessed. The multilayers and PAH-g-PEG coating did not deter the pH-dependent loading and release properties of BSA NPs, and improved the stability of bare BSA NPs. With more PEG on the surface, the NPs were more stable.Then, a PAH-g-PEG-COOH layer was further adsorbed onto the (PAH/PSS)2multilayers-coated BSA NPs and used to covalently bond the aptamer AS1411, which is known to specifically bind the over-expressed nucleolin on cancer cell membrane. Thus, BSA@(PAH/PSS)2/PAH-g-PEG-CONH-Apt NPs (BNPs-Apt) were obtained. The multilayers and PAH-g-PEH-COOH coating did not bring significant influences on both drug loading and release. In vitro cell culture demonstrated that the mount of as-prepared BSA NPs (BNPs-Apt) uptaken by QGY-7703was higher than the mount of the ones uptaken by Hepli, which means BNPs-Apt could be specifically delivered to liver cancer cells. Comparing with free DOX and BNPs/DOX, BNPs-Apt/DOX led to higher cytotoxicity.Finally, the PAH/PSS systems were substituted by poly (L-lysine)(PLL)/Heparin (Hep) system, which is biodegradable and has more active groups. PLL/Hep multilayers and PLL-g-PEGwith different grafting ratios were coated on the surface of BSA NPs. In vitro measurements demonstrated that PLL/Hep multilayers and PLL-g-PEG coated BSA NPs had good stability and hemocompatibility. Preliminary tests in vivo (blood clearance and biodistribution) showed targeting potential, which is crucial for further study.