| ObjectiveBy synthesizing a magnetic nanoparticles ionp-peg-pd-l1 targeting probe with the target of immunotherapy pd-l1,the cross-sectional imaging of two tumor models with different pd-l1 expression was performed by using magnetic resonance to realize the identification of pd-l1 expression in different tumors.MethodsFe3O4 coated with homogeneous oleic acid was prepared by oil phase method,and then modified PEG to convert into aqueous iron oxide nanoparticles.Finally,pd-l1 targeting antibody was coupled to peg-modified iron oxide nanoparticles to prepare a targeted probe,and the physical characterization of the synthesized probe was detected and the imaging effect was observed.Targeted by cytotoxicity experiments to test probe of the cell toxicity,chose two different PD-L1 expression level of cell lines,one is low PD-L1 expression of 4 t1 breast cancer cell line,the other is a kind of PD-L1 expressed higher cell line CT colon cancer cell line-26 building model to carry on the cellular level and the level of animal experiment to observe the probe of the intake and the effect of magnetic resonance imaging.At the cellular level,two different tumor cells were incubated for 6 hours with a targeted probe,and then the cells were stained with Prussian blue and observed with an inverted fluorescence microscope.At the animal level,magnetic resonance imaging was used to observe two tumor models with differential pd-l1 expression.Finally,respectively,to not to probe in mice,and to probe the mice of 24 hours after main tissues after cervical dislocation and HE staining to observe its effect on the bodytissue,this experiment using MRI for the first time based on PD-L1 targeting of ferroferric oxide probe for magnetic resonance imaging,tumor immunotherapy for clinical observation on the curative effect of decision-making and provide a new method.Results1.Physical characterization of IONPs-PEG-PD-L1: the size of IONPs-PEG-PD-L1 is about 10 nm,the particle size is relatively uniform,the dispersity is good,and the shape is square.The dynamic light scattering shows that the hydration particle size is normally distributed around 25 nm,and the point position is about negative 20.Fourier infrared observations showed that the characteristic absorption wavelength of IONPs-PEG-PD-L1 after PEG modification was around1100 nm.2.Cytotoxicity test: the cytotoxicity test of CCK8 showed that ionp-pd-l1 was not toxic to 4T1 and CT26 cell lines.3.Cell uptake experiment: the Prussian blue staining of the targeted probe on the cell lines 4T1 and CT26 with different PD-L1 expression showed that the CT26 with high pd-l1 expression was significantly higher than the 4T1 with low pd-l1 expression.4.Magnetic resonance animal imaging: the ionp-pd-l1 targeting probe has more significant changes in the imaging signal of CT26 tumor model than that of 4T1 tumor model,indicating that it has certain application value in the observation of pd-l1 differences in animal imaging.ConclusionIn this study,a kind of PD-L1 active targeting nanoprobe was synthesized.At the cellular level,it showed good ability of tissue targeting.At the animal level,it was shown that the targeted probe in the CT26 tumor model with high expression of PD-L1 had an obvious imaging effect compared with the 4T1 tumor model with low expression of PD-L1,which provided a new method for the improvement of immunotherapy. |
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