Preparation Of SDF-1-Targeted Fe₃O₄/PLGA/PFH Nanoparticles And The Study Of Imaging And Targeting Experiments On Tongue Squamous Cell Carcinoma Cells In Vitro

Objective To prepare a targeted polymer contrast agent modified by SDF-1 and coated with Fe₃O₄particles and liquid fluorocarbon PFH and detected its properties of physics and optics.To evaluate ultrasonic and photoacoustic imaging effects in vitro,targeting ability of SDF-1/Fe₃O₄/PLGA/PFH NPs qualitatively and quantitatively.Methods The nanoparticles（NPs）were prepared by double emulsification method.SDF-1 was connected to PLGA shell through thioether bonds,thus polymer contrast agent with targeting effect was prepared.The morphology of NPs was observed by optical microscope and scanning electron microscope and the attachment of SDF-1 to NPs was observed by laser confocal microscope.The particle size,distribution,and zeta potential were assessed.Atomic absorption spectrophotometry（AAS）was used to determine Fe₃O₄concentration loading in NPs.UV-vis spectrophotometry was used to measure the absorption spectra of NPs.The corresponding imaging models were established.The photoacoustic（PA）signalsofSDF-1/Fe₃O₄/PLGA/PFH,Fe₃O₄/PLGA/PFH,SDF-1/PLGA/PFH and blank PLGA NPs at different concentrations under the excitation of 680nm pulse laser were examined.The imaging of targeted NPs at different concentrations and different mechanical coefficients（MI）were observed by ultrasonic apparatus,and echo intensity values（EI）at different MI values and different concentrations were calculated.Proper concentration of SDF-1/Fe₃O₄/PLGA/PFH and blank PLGA NPs were put into a water bath,heating to 65℃from 37℃,recording ultrasonic images of the two groups before heating and when heating to about 56℃by ultrasonic apparatus,calculating EI values of the corresponding two-dimensional grayscale ultrasound imaging and contrast-enhanced ultrasound imaging of SDF-1/Fe₃O₄/PLGA/PFH NPs.And the phase transformation process of the them were recorded under a light microscope.The targeted binding ability to SCC-15 cells of SDF-1/Fe₃O₄/PLGA/PFH NPs were observed by a full-automatic fluorescence microscopy.The targeting ability of SDF-1/Fe₃O₄/PLGA/PFH NPs were detected by flow cytometry quantitatively.Results The solution of prepared targeted NPs was dark brown,and their morphology were regular,well dispersed,round and spherical,with scattered holes formed on the surface under scanning electron microscope（SEM）.The average particle size was（586.48±124.70）nm and average zeta potential was（-21.5±2.17）m V.The concentration of Fe₃O₄in the sample was 35.74μg/m L.The targeted NPs had two stronger absorption peaks in the wavelength range of 300～840nm,which were located near 556nm and623nm respectively.Obvious PA signals were detected of SDF-1/Fe₃O₄/PLGA/PFH NPs and Fe₃O₄/PLGA/PFH NPs,and the mean PA signals increased with the increase concentration of the nanoparticles（P<0.05）.The ultrasonic signals of the SDF-1/Fe₃O₄/PLGA/PFH NPs were increased with the increase of MI value and concentration of the NPs（P<0.05）.The EI values of two-dimensional grayscale ultrasound imaging and contrast-enhanced ultrasound imaging could be enhanced after the phase transformation at 56℃（P<0.05）.A large number of nanoparticles were attached around the membrane and cytoplasm of SCC-15 cells,showing bright green light in fluorescence mode.The binding rate of SDF-1/Fe₃O₄/PLGA/PFH NPs to SCC-15 cells was 84.44%.Conclusion The targeted NPs loaded with Fe₃O₄were successfully prepared,with regular morphology,spherical shape,basically uniform and high encapsulation efficiency.In addition,the targeted NPs had two absorption peaks in the wavelength range of300～840nm and possessed good optical absorption,which laid a foundation of photoacoustic imaging experiment in vitro.The targeted NPs prepared were targeted to SCC-15 cells,which had good multimodal imaging ability of ultrasound and photoacoustic imaging and could lay a preliminary foundation of establishing the procedures and standards for the diagnosis of primary tongue cancer and metastatic lymphoma.