Studies On Targeted Aptamer Coupling Fe₃O₄ Nanoparticles

Purpose:The aptamer(an oligonucleotide target in AS)cross-coupling Ultrasmall Superpa-ramagnetic Iron Oxide(USPIO)nanoparticles,synthesize a new targeted USPIO nanop-articles in atherosclerosis.At the same time we discuss the feasibility of preparation and the effect of preparation used on AS diagnosis.Methods:Firstly,taking the particle size as the main indicators,investigated the process o f preparation of Fe3O4 magnetic nanoparticles and determine the process of preparat ion,later on,the 3-ami-nopropyl-triethoxysilane though silane reaction in the form of chemical bonds combine the Fe3O4 nanoparticles and conduct the Fe3O4 magnetic n-anoparticles modified by silane.the particle size,crystal structure,chemical structur e and magnetic properties were characterized by particle size instrument,XRD,IR and magnetism performance testing.Then aptamer was cross-linked with the particles,an-d then identified the conjugation of COOH-apt and particles though HPLC and IR.Furthermore,used the freeze-drying technology to improve the stability of USPIO.Finally,we injected the USPIO nanoparticles agents into the ApoE-/-mice,then thr o-ugh the pathological section of different organs of mice to evaluate if the MR1 co nt-rast agents reach AS plaque.Results:1.The preparation and surface chemical structure of material-coated USPIO:1.1?XRD result confirmed that this particles is the inverse spinel structure.according to TEM measurement and grain-size instrument,The diameter is about 30nm.1.2?Adsorption of functional groups on the surface of USPIO which coated wi th(3-aminopropyl)triethoxysilane in FT-IR.All the figures indicated that the couple a gent had been introduced onto the Fe3O4 surface.And aptamer were successfully cou pled with the nanoparticles which surfaced amino functionlization.1.3?According to the DNA content determination of supernatant,as the reaction time,the content decrease.The result indicated that aptamer were successfully coupled with the nanoparticles.2.Discoveries found in vivo and vitro of USPIO:2.1?In 6 hole cell culture plate,the foam cells can phagocytose the nanoparticles.2.2?Conduct the USPIO to be the targeted agent injection.Injected it into the ApoE-/-mice,observe the distribution of the nanoparticles of different organs in m ice,the nanoparticles appear in the lesions of atherosclerosis plaques.Conclusion:We conduct Fe3O4 magnetic nanoparticles by chemical coprecipitation and modif-ied it by silane.In addition,COOH-apt were successfully coupled with the nanoparti-cles modified silane and conduct a new targeted USPIO nanoparticles.The result of ApoE-/-mice MRI indicated the new targeted nanoparticles agents reach the lesion s of atherosclerosis plaques.It has the potential to be a new type of MRI contrast a gent of AS.