【摘要】：作為可降解生物金屬材料,鎂及鎂合金與自然骨的抗拉強度、抗壓強度、彈性模量和密度均比較相似,力學(xué)相容性以及生物相容性好,因此,鎂及鎂合金逐漸成為最具有開發(fā)潛力的可降解生物材料。本文采用熱擠壓變形和時效處理等工藝方法制備生物Mg-8Gd-4Y-xZn-0.5Zr(x=1,2 wt%)合金,利用電化學(xué)腐蝕實驗和浸泡腐蝕降解實驗,對比研究不同狀態(tài)合金在Hank's模擬體液中的腐蝕降解速率;通過采用OM, SEM,XRD等技術(shù)手段對腐蝕后的試樣表面及腐蝕產(chǎn)物形貌進行分析,探究其腐蝕類型和腐蝕程度及腐蝕機理;借助MTT法考察不同Mg-8Gd-4Y-xZn(x=0, 1,2, 3 wt%)合金對小鼠預(yù)成骨細胞(MC3T3-E1)、人骨肉瘤細胞(Saos-2)、骨髓間充質(zhì)干細胞(hTMSC)的細胞毒性。得到以下結(jié)論:(1)時效處理后Mg-8Gd-4Y-1Zn-0.5Zr合金析氫量從28 ml降至20 ml,腐蝕速率從7.247 mm/a 降至 5.691 mm/a,而 Mg-8Gd-4Y-2Zn-0.5Zr 的析氫量從 30 ml 降至 23ml,腐蝕速率從8.748 mm/a降至7.164 mm/a。由此可見,時效處理減輕了合金的腐蝕。(2)SEM形貌顯示腐蝕產(chǎn)物均為片層狀龜裂結(jié)構(gòu),大部分比較平整,出現(xiàn)了典型的點蝕坑。時效過程中,合金發(fā)生了靜態(tài)回復(fù),空位數(shù)量、位錯密度降低,殘余應(yīng)力得以釋放,有利于合金耐蝕性能的提高。XRD結(jié)果表明,腐蝕產(chǎn)物主要由Mg(OH)2組成,并摻雜有MgO、Mg3(PO4)2、Ca(PO3)2等物質(zhì)。時效后合金的開路電位、極化曲線趨于向正移動,腐蝕電流減小,高頻容抗弧也隨之增大,合金耐蝕性都有所增強,腐蝕速率有所降低。(3)合金在SBF溶液腐蝕過程中,合金表面會發(fā)生反應(yīng)析出大量的H2,隨著溶液不斷的被堿化,浸泡10 h后溶液pH達到10.5左右。擠壓態(tài)合金在SBF溶液中的腐蝕速度高于時效態(tài)合金的腐蝕速度。試樣的離子濃度在SBF和培養(yǎng)液中規(guī)律基本一致,在時效態(tài)合金中的析出量較擠壓態(tài)合金的低。(4) MC3T3-E1 細胞、hTMSC 細胞在 Mg-8Gd-4Y-xZn(x=0, 1,2, 3 wt%)浸提液中培養(yǎng)1天和3天后,當(dāng)浸提液濃度為100 %時,合金的細胞毒性均屬于無毒或微毒范疇,當(dāng)浸提液濃度為50 %和25 %時,細胞增殖率達到80 %以上,細胞毒性均為0級。證明合金的生物性良好,適宜用作生物醫(yī)用植入材料。(5) MC3T3-E1細胞和hTMSC細胞經(jīng)過25%浸提液培養(yǎng)24 h后,大部分細胞呈梭形,幾乎無任何異常狀態(tài)出現(xiàn)。隨著Zn含量的增加,細胞的增殖呈現(xiàn)出先增加后降低的趨勢。掃描電鏡觀察hTMSC細胞的生長狀態(tài),細胞多為長梭形,時效態(tài)合金浸提液培養(yǎng)過后的伸展?fàn)顟B(tài)良好,并且細胞長出偽足與臨近細胞交聯(lián)呈網(wǎng)狀。
[Abstract]:As biodegradable biomaterials, magnesium and magnesium alloys have similar tensile strength, compressive strength, elastic modulus and density with natural bone. Magnesium and magnesium alloys are becoming the most promising biodegradable biomaterials. In this paper, the biological Mg-8Gd-4Y-xZn-0.5Zr (x1 + 2 wt%) alloy was prepared by hot extrusion deformation and aging treatment. The corrosion degradation rate of different state alloys in simulated body fluid of Hank's was studied comparatively by electrochemical corrosion test and immersion corrosion degradation experiment. The corrosion types, corrosion degree and corrosion mechanism of the samples after corrosion were analyzed by means of OM, SEM,XRD and other techniques. The cytotoxicity of different Mg-8Gd-4Y-xZn (xn0, 1, 2, 3 wt%) alloys to mouse preosteoblasts (MC3T3-E1), human osteosarcoma cells (Saos-2) and bone marrow mesenchymal stem cells (hTMSC) was investigated by MTT assay. The following conclusions are obtained: (1) after aging treatment, the hydrogen evolution rate of Mg-8Gd-4Y-1Zn-0.5Zr alloy decreases from 28 ml to 20 ml, from 7.247 mm/a to 5.691 mm/a, while that of Mg-8Gd-4Y-2Zn-0.5Zr decreases from 30 ml to 23 ml, and the corrosion rate decreases from 8.748 mm/a to 7.164 mm/a.. It can be seen that aging treatment alleviates the corrosion of the alloy. (2) SEM morphology shows that the corrosion products are lamellar crack structure, most of them are flat, and typical pitting pits appear. During aging, static recovery occurs, the number of vacancies and dislocation density decrease, and the residual stress is released. The XRD results show that the corrosion products are mainly composed of Mg (OH) _ 2 and doped with MgO,Mg3 (PO4) _ 2Ca (PO3) _ 2. After aging, the open circuit potential and polarization curve tend to move positively, the corrosion current decreases, the high frequency capacitance arc resistance increases, the corrosion resistance of the alloy increases and the corrosion rate decreases. (3) during the corrosion process of SBF solution, the corrosion resistance of the alloy increases. A large amount of H _ 2 was precipitated on the surface of the alloy, and the pH of the solution reached about 10.5 after 10 h immersion with the solution continuously alkalized. The corrosion rate of extruded alloy in SBF solution is higher than that of aged alloy. The ion concentration of the sample was basically consistent with that of the culture medium, and the precipitation amount in the aging alloy was lower than that in the extruded alloy. (4) MC3T3-E1 cells and hTMSC cells were cultured in the Mg-8Gd-4Y-xZn (x0, 1, 2, 3 wt%) extractions for 1 and 3 days, when the concentration of the extracted solution was 100%. The cytotoxicity of the alloy belongs to the category of non-toxic or micro-toxic. When the concentration of extract solution is 50% and 25%, the cell proliferation rate is more than 80%, and the cytotoxicity is 0 grade. The results showed that the alloy had good biological properties and was suitable for biomedical implantation. (5) after 24 h culture of MC3T3-E1 cells and hTMSC cells, most of the cells were fusiform and had almost no abnormal state. With the increase of Zn content, cell proliferation increased first and then decreased. The growth state of hTMSC cells was observed by scanning electron microscope. Most of the cells were fusiform, the extended state of aging alloy extract was good, and the pseudopodia grew into a network of adjacent cells.
【學(xué)位授予單位】：西安理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG172;TG379;TG166.4

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