以阴离子多肽为模板合成二氧化硅纳米空心球

摘要

Anionic polypeptide,the poly(sodium L-glutamate),was applied to fabricate microporous silica hollow nanospheres templated by the secondary structures of the polypeptide as porogens.In the synthesis,3-arninopropyltfimethoxysilane(APMS)and tetraethyl orthosilicate(TEOS)were used as the silica sources.and the coassembly followed the mechanism of the aniomc surfactant-templated mesoporous silica(AMS)through a S-N+-I-pathway,where S indicates the anionoc polypeptide,I indicates inorganic precursors(TEOS),and N indicates costructure-directing agent(APMS),which interacted with the negatively charged anionic polypeptide secondary structures electrostatically and cocondensed with silica source to form the silica framework.The product WaS subiected to characterizations of X-ray diffraction(XRD),infrared(tR)spectroscopy,thermogravimetric(TG)analysis,scanning electron microscopy(SEM),transmitted electron microscopy(TEM),and nitrogen adsorption-desorption measurement.It was found that the pH value of the synthesis solution was an important factor to the morphological control of the silica products.Besides the microporous hollow nanospheres,microporous submicron silica solid and hollow spheres were also obtained facilely by changing the synthesis parameters.Our study further implied that anionic polypeptides,which were abk to control mineralization of calcium carbonate and calcium phosphate.could also induce silica condensation in the presence of proper silica precursors.It was also expected that functional calcium carbonate (phosphate)/silica-nanocomposite materials would be fabricated under the control of the anionic polypeptide.%以聚阴离子多肽(聚谷氨酸钠)控制合成了微孔二氧化硅空心球.在合成过程中,以3-氨丙基三甲氧基硅烷(APMS)和正硅酸乙酯(TEOS)为硅源,聚谷氨酸钠为模板.硅源与阴离子多肽模板之间的组装依照以阴离子表面活性剂为模板剂组装合成介孔二氧化硅的机理,即S-N+-I-机理,其中S表示阴离子多肽,I表示TEOS,N表示共结构导向剂APMS.组装过程中质子化的APMS与阴离子多肽之间形成静电相互作用,同时,AMPS和TEOS共同水解聚合形成围绕阴离子多肽模板的二氧化硅骨架,多肽的二级结构为微孔孔道的模板.以阴离子多肽为模板可以在不同的实验条件下控制微孔纳米空心球,微孔亚微米空心球和实心球形貌的合成.在生物矿化过程中,阴离子多肽往往控制碳酸钙或磷酸钙的沉积,而我们的实验结果表明,在适当的硅源存在下,阴离子多肽也可以诱导二氧化硅的沉积.