| Summary: | 碩士 === 國立成功大學 === 分子醫學研究所 === 104 === The advancements in chemical engineering and materials science have contributed to the development of different types of nanomaterials, composed of either inorganic or polymer based nanoparticles that useful for nanotheranostics applications. Magnetic nanoparticles (MNPs) are a major class of nanomaterials. Their unique magnetic properties make them used as magnetic resonance imaging (MRI) contrast agents. Among them, FePt alloy nanoparticles (FePt NPs) have excellent super-paramagetic properties and stability combined with high X-ray absorption ability, making FePt NPs as a potential MRI/CT dual non-invasive imaging contrast agent. In this study our aim is to develop multifunctional FePt NPs for two purposes, that is they should enhance the radiotherapy efficacy and act as dual MRI/CT imaging contrast agent. Nanoprecipitation method was employed to prepare modified FePt@PLGA with synthesized particles sized 152.8 ± 23.9 nm and encapsulated efficiency was 97 ± 2.83%, detected by DLS and ICP-AES. Different cell lines 4T1, AS2, Hep3B, and CL1-5 were treated with modified 6 nmFePt@PLGA NPs (2mg/ml) for 24 hours and then combined with ionizing radiation to evaluate the synergetic effect for radiotherapy. By using clonogenic assay we have found that the 6 nm FePt@PLGA NPs exhibited no enhanced mortality of 4T1 and AS2 cells when compared to that of cells with ionizing radiation alone. Furthermore, to examine functional peptide DG2 that recognizes NRP-1 protein, FePt@PLGA NPs surface was modified to conjugate streptavidin through EDC binding ligand with biotin-DG2 for in vivo study. Therefore, Neuopilin-1 protein was over-expressed in 4T1 cells, and stably colony No. 56 (4T1-56) was selected as a model for further study. According to Western blot result that 4T1-56 cells expressed higher NRP-1 protein levels than the parental 4T1 cells. In vivo study, tumor formation induced by injected 4T1 and 4T1-56 cells in nude mice subcutaneously formed primary tumor within two weeks. FePt@PLGA-DG2 NPs (0, 4, and 24 hours later) was injected into tail vein and detected by IVIS, meanwhile tumor section was treated by iron stain to confirm the presence of Fe ions. As bioluminescent results show mice injected with NPs had lower luminescence compared to that of PBS groups due to the quencher effect. In addition, the result of iron staining indicated NRP-1 expression effect Fe present of the internal part of 4T1-56 tumor and peripheral part of 4T1 tumor. Overall, FePt@PLGA-DG2 NPs was synthesized successfully in this study, with functional surface modification of NPs that exhibited specific binding capability to both DG2 peptide and NRP-1 protein in vivo, so they have high potential as targeted agent for tumor diagnosis.
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