Preparation And Study Of Gd,Eu Doped Hydroxyapatite Nanoparticles With Magnetic And Fluorescent Properties

Hydroxyapatite(HAP)is the main inorganic component in human and animal bones and teeth.It has good biocompatibility,bioactivity and bone conduction.Based on its good biocompatibility and enhanced degradation in intracellular acid environment,HAP nanoparticles have good application prospects in drug carrier,imaging agent matrix and inorganic bio-composite materials.Based on its unique crystal structure,Ca²⁺is easy to be replaced by rare earth ions in the crystal cell,so it can be used as a matrix material for rare earth ions.Gadolinium(Gd),with seven uncoordinated 4f orbital electrons,has large spin magnetic moment and high relaxation efficiency.It is an excellent paramagnetic metal ion for MRI contrast agent.It is expected that biocompatible nano MRI contrast agent can be obtained by doping Gd³⁺into nano HAP lattice,combining the good biocompatibility of HAP and the excellent magnetic properties of gadolinium ion.Europium(Eu)ion exhibits good fluorescence performance.By co-doping the rare earth element,a new kind of biocompatible,fluorescent and magnetic nanomaterial can be obtained.Firstly,gadolinium-doped hydroxyapatite nanoparticles were prepared by precipitation method combined with hydrothermal method and polyacrylic acid complexation method.On this basis,Gd/Eu Co doped hydroxyapatite nanoparticles were prepared by coprecipitation method combined with polyacrylic acid complexation method.Combined with ultrasonic effect and dispersant stabilization mechanism,HAP nano particles can be uniformly dispersed in water and maintain stable.The effects of rare earth doping amount,reaction temperature and high temperature calcination heat treatment on the phase composition,grain size,morphology,crystallinity,fluorescence and magnetic response of Gd/Eu co-doped HAP were studied.The research contents and results of this paper are as follows:(1)Based on the combination of precipitation method and hydrothermal method and polyacrylic acid complexation method,nano hydroxyapatite with different gadolinium ion content was synthesized at different temperatures,and some samples were calcined at high temperature.The results show that the doping of gadolinium ion does not change the crystal phase composition of HAP,and the product is rod-shaped nanoparticles,which can be uniformly and stably dispersed in aqueous solution through PAA dispersant.With the increase of reaction temperature,crystallinity and grain size,magnetic properties increased slightly.With the increase of gadolinium doping content,the crystallinity decreased,the grain size changed little,and the magnetic properties increased linearly.After high temperature calcination heat treatment,the crystallinity is greatly improved,the grain size is obviously larger,and the magnetic properties are not obviously changed.The crystallinity of the nanoparticles prepared by PAA complex method is decreased,and the grain size is small,which has little effect on the magnetic properties.(2)Gd/Eu nanoparticles with different doping ratio were synthesized by coprecipitation method.The results show that the addition of europium ion does not change the crystal composition of HAP,the morphology of the product changes to needle shape,the powder is easy to agglomerate,and the product can be evenly dispersed in aqueous solution.With the increase of europium ion content,the fluorescence intensity increases,but the magnetic properties are less affected.