Mg、Fe、Zn三類金屬及其合金是應(yīng)用最多、研究最廣的生物可降解金屬支架材料。其中金屬Fe具有良好的生物相容性和機(jī)械性能，是發(fā)展最早，也是最有潛力替代永久性支架的材料之一，但它相對(duì)較慢的降解速率一直是制約其發(fā)展的關(guān)鍵問題。

為解決這個(gè)問題，大連理工大學(xué)材料學(xué)院王偉強(qiáng)團(tuán)隊(duì)提出將活性更高的Zn與Fe合金化，制備以Fe為基體的Fe-Zn合金，有望滿足降解速率要求，同時(shí)保留鐵的固有機(jī)械性能。而Zn與Fe熔沸點(diǎn)差距大，給材料制備也增加了難度。為獲得質(zhì)量較好的Fe-Zn合金，用電沉積來替代傳統(tǒng)的冶金手段不僅可以獲得熔沸點(diǎn)差距較大的二元合金，同時(shí)這種原子級(jí)的互競共沉積也可以得到亞穩(wěn)態(tài)的Fe-Zn合金，進(jìn)一步提高材料的腐蝕速率。在這份工作中還對(duì)合金進(jìn)行了層狀結(jié)構(gòu)設(shè)計(jì)，通過調(diào)控電參數(shù)，制備了納米晶和超細(xì)柱狀晶組織交替生長的層狀結(jié)構(gòu)。評(píng)估了合金的成分、微觀結(jié)構(gòu)、機(jī)械性能、體外降解性能和生物相容性。

研究結(jié)果顯示，所有合金的基體均為亞穩(wěn)態(tài)的有序固溶體相，其中只有Zn含量提高到11.6%時(shí)才有細(xì)小的第二相析出（室溫下Zn在Fe中的溶解度小于2%）。層狀Fe-Zn合金的屈服強(qiáng)度超過350MPa，延伸率超過20%，并且通過浸泡測(cè)試所得的腐蝕速率高達(dá)0.367mm/y。不僅如此，層狀設(shè)計(jì)還解決了Fe基材料的局部腐蝕問題。在隨后的血液相容性和細(xì)胞相容性測(cè)試中，低Zn含量的單層和多層Fe-Zn合金均表現(xiàn)出良好的生物相容性。該研究以“The enhancement of mechanical properties and uniform degradation of electrodeposited Fe-Zn alloys by multilayered design for biodegradable stent applications”為題發(fā)表在生物材料領(lǐng)域的權(quán)威期刊《Acta Biomaterialia》上。

文章連接：

https://doi.org/10.1016/j.actbio.2023.02.029

文章整體思路

Fig. 1. (a) XRD patterns of the electrodeposited Fe-Zn alloys and the magnification of diffraction peak of (110). (b) Schematic diagram of the microstructure of multilayered alloy. (c) The microstructure of Fe-Zn alloys with monolayered structure and multilayered structure and the enlarged view of areas ⅰ and ⅱ of multilayered alloys.

Fig. 2. The TEM analysis of Fe-Zn alloys. 

Fig. 3. Tensile properties of Fe-Zn alloys. (a)The tensile curves. (b)Fracture morphologies observed by SEM.

Fig. 4. Corrosion assessment of the Fe-Zn alloys. (a) Potentiodynamic polarization curves. (b) The corrosion rate measured by the weight-loss method after immersion test. (c and d) XPS spectra of Fe-11.6Zn alloy after immersion.

Fig. 5. The corrosion morphologies of Fe-Zn alloys. (a) Cross-section morphologies of Fe-Zn alloys after immersion test for 7, 28, 56 d. (b) Surface morphologies of Fe-4.6Zn and layered Fe-4.6Zn after immersion test for 56 d.

Fig. 6. Schematic diagram of corrosion mechanism of monolayered (a, b) and multilayered Fe-Zn alloys (c, d) at the initial (a, c) and later (b, d) stages of immersion test.

Fig. 7. Cytotoxicity assessment of HUVECs on the surfaces and in the extracts of the Fe-Zn alloys. 

Fig. 8. Blood compatibility tests on the Fe-Zn alloys (316L stainless steel as control). (a) Hemolysis rates of stainless steel and Fe-Zn alloys. (b) The whole blood clotting on different surfaces for up to 90 min. (c) The adhesion morphology of platelets on Fe-Zn alloys.

綜合上述分析，電沉積所制備的層狀Fe-Zn合金很有希望能滿足生物可降解支架的應(yīng)用標(biāo)準(zhǔn)，開創(chuàng)鐵基材料在冠心病介入治療領(lǐng)域的新篇章。