Synthesis Of Multifunctional Nanoparticles System For Imaging And Treatment In Atherosclerosis

Atherosclerosis can cause a series of serious sudden cardiovascular and cerebrovascular diseases, which are the main factors threatening human health. The pathological process and predisposing factors of this chronic disease have reached a uniform conclusion in the world of medicine. At present, the effective means of operation such as vascular stenting and surgery can be performed on it. But the means of detection and treatment can be used in late stage of this disease. This is due to the vascular wall thickening and lesion to the outside of the tube wall rather than lumen the early stage of the disease. Therefore, the current diagnosis and treatment are lagging behind. Diagnosis and treatment of this disease in the early stage is a fundamental way to avoid the effective method of treatment. In order to achieve this goal, nanoparticles diagnosis and treatment system has been widely studied and can be used as a promising alternative solution. In the early stages of atherosclerosis, a variety of biological factors gather in the affected area and further release other biological factors to induce a series of disease, so, these factors can be used as biological targets of the nanoparticles diagnosis and treatment system. In this work, we have selected macrophages and macrophage migration inhibitory factor as the target and designed a variety of multifunctional nanoparticles for the early diagnosis and treatment.First, we use the synthesis method of ATRP to preparing PGMA of different molecular weight from 5000 to 10000. The ring opening reaction by a large excess of EDA was done to get PGMA-EDA which contains a lot of amino terminal. To improve the biological compatibility and targetability, PEG2000 and DS were respectively modified to the PGMA-EDA by amidation reaction and reductive amination. Then, the final product PGMA-EDA-g-PEG-g-DS@IO was synthesized by ligand exchange reaction. In this process, we selects the Mn=5.03×103 PGMA as the best main polymer by the result of TEM. 1H NMR and FTIR were verified for each step of the reaction process. The molecular weights of each product were characterized by GPC. The results proved the successful synthesis of the products. The DLS and TEM results show that the final product particle size was about 15 nm in diameter and has a good dispersion, and showed excellent biocompatibility in the cytotoxicity test. The above results confirmed that PGMA-EDA-g-PEG-g-DS@IO could play an significant role of MRI in the atherosclerosis.Secondly, from the optimization point of before work, we chose the G3.0 PAMAM with better solubility and biodegradability as the main polymer. Dextran sulfate(DS) and Rhodamine B(RB) were grafted to PAMAM-g-PEG continuously through reductive amination and amidation reaction to synthesize PAMAM-g-PEG-g-DS-g-RB. The structure of PAMAM-g-PEG-g-DS-g-RB was characterized through nuclear magnetic resonance(1H NMR) and fourier transform infrared spectroscopy(FTIR). A new water-soluble superparamagnetic iron oxide nanoparticles(IONPs) has been synthesized through simple ligand exchange between the iron oxide nanaparticles and PAMAM-g-PEG-g-DS-g-RB. The analysis of transmission electron microscopy(TEM) indicated that micelles were well dispersed in water and had uniform sizes(about 10nm). The result of thermogravimetric analysis(TGA) proved that about 83%(mass fraction) polymers were coated on the surface of IONPs. The MRI in vitro evaluation demonstrated a high R2 value(130.8 m M-1s-1) to be served as a T2-weighted contrast agent. The cell counting kit(CCK) assay showed no significant toxicity in RAW264.7. The above results confirmed that PAMAM-g-PEG-g-DS-g-RB@IO could play an significant role of MRI and FLI in the atherosclerosis.In the fourth chapter, according to the initiator that there is no obvious specific biological characteristic around atherosclerosis area, we designed and synthesized the light-sensitive drug release system PAMAM-g-ISO-1-g-FS. The drug fluvastatin was modified to the PAMAM through light sensitive switch. The target molecule ISO-1 was also modified to the main polymer by amidation reaction. 1H NMR and mass spectrum were verified for each step of the reaction process. The result of LCMS showed that after 312 nm ultraviolet irradiation, fluvastatin was separated from main polymer, the cumulative drug release rate of 2h was 23%, achieve the purpose of controlled drug release.In conclusion, in this work, we synthesized three kinds of nanoparticles for diagnosis and treatment of atherosclerosis, the excellent properties they exhibited make it possible for future clinical application.