Study On Preparation And Cell Imaging Of Non-spherical Fluorescent ?-Fe₂O₃ Nanoparticles

Nanoparticles,as carriers of drugs,imaging agents and therapeutic agents,have been the focus of research in nanomedicine in recent years.Compared with spherical nanoparticles,non-spherical nanoparticles have significant different properties in the field of drug delivery,such as longer blood circulation time,lower macrophage uptake rate or higher tumor cell uptake rate.However,up to now,there is still a lack of systematic research on the biological properties of non-spherical nanoparticle carriers,especially the influence of nanoparticles morphology on drug delivery system.The differences in experimental design and nanomaterial properties in various independent studies lead to the diversity of research conclusions.a-Fe₂O₃ have the advantages of relative ease of synthesis,surface modification,controllable morphologies and good biocompatibility.So a-Fe₂O₃ were used as the model system in this paper.Spindle shape,ellipsoidal shape and quasi-spherical shape a-Fe₂O₃nanoparticles were prepared by classical hydrothermal method.Two groups of fluorescent nanoparticles were obtained by post-modification of thin SiO₂ shell containing small molecule fluorescent dyes with aggregation-induced fluorescent enhancement effect.The effect of the morphology of fluorescent nanoparticles on the rate of into cells was preliminarily revealed.The main contents of this paper are as follows:Chapter 1:Introduction.On the basis of reviewing the research progress of nanoparticle carriers and effect of their morphologies on biological behavior,the research topic of this paper is proposed.Chapter 2:Study on preparation and cell imaging of non-spherical fluorescent?-Fe₂O₃nanoparticles?FNP1?.Spindle shape,ellipsoidal shape and quasi-spherical shape a-Fe₂O₃nanoparticles were prepared by hydrothermal method.Polyvinylpyrrolidone?PVP?was used to stabilize a-Fe₂O₃,and the compound of a-Fe₂O₃@PVP was obtained.Tetraphenylethene-functionalized siloxane?AIEgen1?and tetraethylorthosilicate?TEOS?were added to a-Fe₂O₃@PVP system,and three morphologies of FNP1 were prepared by one pot sol-gel reaction?spindle shape,ellipsoidal shape and quasi-spherical shape were recorded as SNP1,ENP1 and QSNP1 respectively?.The effects of the contents of AIEgen1 and TEOS on the particle size and fluorescence emission spectra of SNP1 were investigated by transmission electron microscopy?TEM?and fluorescence spectrometer,respectively.The results show that thickness of SiO₂ shell increased with the increase of TEOS.By adjusting the concentration of these components,the thickness of SiO₂ shell can be controlled in the range of 26-54 nm.The results showed that the more AIEgen1 or TEOS,the stronger the fluorescence of fluorescent nanoparticles,the higher the fluorescence quantum yield.Dynamic light scattering?DLS?experiments show that the Zeta potentials of spindle shape,ellipsoidal shape and quasi-spherical shape nanoparticles are-24.3 mV,-26.1 mV and-29.6mV,respectively,indicating that the surface of FNP2 nanoparticles is negatively charged.In addition,FNP1 has low cytotoxicity and good photostability.Confocal fluorescence microscopy was used to study the effect of morphology of FNP1 on its uptake behavior.The preliminary results show that the rate of spindle shape and ellipsoidal shape nanoparticles entering cells was similar,while the rate of quasi-spherical shape nanoparticles was lower than that of spindle shape and ellipsoidal shape.Chapter 3:Study on preparation and cell imaging of non-spherical fluorescent?-Fe₂O₃nanoparticles?FNP2?.Similar to the chapter 2,tetraphenylethene-functionalized siloxane?AIEgen2?and TEOS were used for sol-gel reaction on the three surface of the a-Fe₂O₃@PVP and three morphologies of FNP2 were obtained?spindle shape,ellipsoidal shape and quasi-spherical shape were recorded as SNP2,ENP2 and QSNP2 respectively?.The effect of AIEgen2 and TEOS on the particle size of FNP2 was investigated by TEM.The results showed that self-spheroidization of SiO₂ appeared gradually with the increase of AIEgen2 in the system.With the increase of TEOS concentration,the thickness of SiO₂ increases gradually.The influence of TEOS on the fluorescence spectrum of FNP2 was investigated by fluorescence spectrometer.The results showed that the more TEOS,the stronger fluorescence and the higher fluorescence quantum yield.Zeta potentials of spindle shape,ellipsoidal shape and quasi-spherical shape FNP2 were measured by dynamic light scattering?DLS?.Zeta potentials were+48.2 mV,+51.3 mV and+50.5 mV,indicating that positive charge on the surface of FNP2.The fluorescence imaging of FNP2 with different morphologies in HeLa cells was preliminarily explored.Chapter 4:Summary of the full text.