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The Study on Preparation and Properties of Lanthanum Doped Nano-hydroxyapatite

Author: LiuTianJian
Tutor: WangYouFa
School: Wuhan University of Technology
Course: Biomaterial
Keywords: La doped nano-hydroxyapatite Ion adulteration Crystal lattice parameters Hemocompatibility Biological properties
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 96
Quote: 0
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Abstract


HAP particles have unique biological properties when their size maintained in nano scale.Many rare elements,which existed in natural apatite mineral,could change the crystal structure and bring new biological effects.Among rare elements, La3+ ion has similar radius to Ca2+ ion.And recent studies showed that La/HAP had more excellent thermal stability and acid resistance compared to pure HAP.So,the study on n-La/HAP prepared by nano-technology and its unique biological properties was a potential research orientation.However,due to inferior dispersion of HAP sol combined with the influence on balance of the sol as La entered into the lattice of HAP,this paper focused on three points:the study on dispersion and stability of n-La/HAP sol,the mechanism of La3+ entering into the lattice of HAP and biocompatibility and biological characteristics of n-La/HAP.In this paper,n-La/HAP sol was prepared by chemical precipitation using Ca（OH）2 and Ca（H2PO4）2·H2O as raw materials At the end of this process,the n-La/HAP powders were abtained by freeze drying which could prevent n-La/HAP particles from further aggregation and growth.In paper,the average size analysis and Zeta potential were used to study the influence of ultrasonic treatment,dispersant and pH values on the stability of n-La/HAP.The results showed:appropriate ultrasonic treatment could enhance the stability of sol and its effect reached optimal point when treatment lasted for 5 days. Heparin sodium,sodium hexameta phosphate and sodium polyacrylate chosen as dispersants in experiments reflected different dipersion effects on n-La/HAP sol. Among these three dispersants,sodium polyacrylate had relatively good effect without large fluctuation when preparation situation changed.On the contrary,the effects of heparin sodium and sodium hexameta phosphate changed largely as the change of experimental situation.However,heparin sodium had specific dispersion effect when adjusting pH value to 9.8.Under this situation,the smallest particle size reached about 80nm.With the increase of pH value and amount of dispersants,the average particle size and Zeta potential of n-La/HAP sol decreased continuously at the beginning.After the optimal points of pH value and amount of dispersants,the stability ofn-La/HAP sol turned worse.XRD,FT-IR and ICP were respectively applied to analyze the crystal structure, chemical bond and composition of n-La/HAP powder.Otherwise,particle size analysis,Zeta potential and TEM were respectively used to observe the stability and morphology of n-La/HAP sol.The results showed:because the radius of La3+ was slightly larger than radius of Ca2+,the crystal plane spacing and lattice volume increased when La3+ entered into the lattice of n-La/HAP.A part of OH- transformed into O2- for keeping the balance of charge.And La could improve the stability of crystal when the particle size kept in some scale.With the method of TEM,we observed long rod-shaped n-La/HAP crystals which ratio of length to diameter increased with the increase of amount of La3+.Erythrocyte hemolytic test in vitro and Bel-7402 cells growth inhibition experiment were respectively chosen to evaluate hemocompatibility and biological property of n-La/HAP sol.La3+ could inhibit the growth of BeL-7402 cells to some degree.And hemocompatibility and biological property of n-La/HAP sol were affected by the dispersion and concentration of sol largely Compared with pure HAP and n-La/HAP containing 20%,30%La,n-HAP doped with 10%La had more excellent hemocompatibility and tumor inhibition.

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