| Summary: | 碩士 === 靜宜大學 === 化粧品科學系 === 106 === In recent years, small interfering RNA (siRNA) has attracted increasing attention in the field of gene therapy. Due to their instability, successful delivery of siRNAs to target cells has been pursued. Nanoparticles are extensively studied for the delivery of siRNA. Among the various nanocarriers, zein has excellent biocompatibility, biodegradability, and easy chemical or physical modification. Block copolymer micelles of average nanometer size are straightforward to design and modify.
In this study, we observed that lower PD-L1 expressed in CT-26, B16-F1 and B16-F10 cell line without treating interferon-γ (IFN-γ).However, higher PD-L1 expression in the cell lines of CT-26, B16-F1 and B16-F10 were in a concentration-dependent manner with interferon-γ (IFN-γ) treating. In addition, B16-F1 and B16-F10 cells showed high performance only at low concentrations of interferon-γ (IFN-γ).
In order to achieve efficient siRNA delivery to tumors, we designed novel biodegradable block copolymer micelles by grafting polyethylene glycol monomethyl ether (mPEG) on zein. The synthesized derivatives were characterized by Fourier transform infrared spectroscopy (FT-IR) and confirmed that the mPEG provided functional group NHS ester disappeared at 1740 cm-1. Furthermore, the chemical structure and the grafting rate were determined by nuclear magnetic resonance (1H NMR). Using a differential scanning calorimetry (DSC), the melting point change of the block copolymer micelles were observed to 50°C.
The physiochemical properties of micelles were evaluated by using a dynamic light scattering (DLS), zeta potential analyzer, and a transmission electron microscope (TEM). The results of the mPEG-zein 2 kDa micelles showed that the particle sizes were about 450 nm, PDI were 0.2, and the zeta potential were 4.92±1.62 mV. The mPEG-zein 5 kDa micelles showed that the particle sizes were about 65 nm, PDI were 0.15, and the zeta potential were 9.57±0.301 mV. The morphology was observed using a transmission electron microscope (TEM), both of which were spherical.Moreover, the cytotoxicity and cellular uptake of micelles were also evaluated systematically. The results showed high cell viability in CT-26, B16-F1 and B16-F10 cells. The results showed that as the concentration increased, the fluorescence performance also increased significantly in cellular uptake assay.
The successful development of water-soluble nanocarriers to reduce the use of organic solvents and provide steric hindrance during blood circulation in the body so that the carrier will not be rapidly swallowed and degraded by biological enzymes, but also increase the cellular uptake of the target cells to improve the bioavailability of the drug. These results demonstrated that mPEG-zein modified micelles were promising carriers for siRNA delivery to tumors.
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