Construction Of Three-dimensional Silica Materials And Regulation Of Structures And Properties

Many organisms in nature including diatoms and sponges exhibit high capacity in the construction of biosilica materials.They exhibit sophisticated structures in three-dimensional and special functions,which are formed in mild physiological conditions,such as room temperature,atmospheric pressure and neutral aqueous solution.This attracts great attention and therefore,biomimetic mineralization has become one of the most important methods for the construction of advanced inorganic nanomaterials.At present,the biomimetic synthesis of silica is mainly focused on the construction and regulation of zero-or one-dimensional materials.It is still a challenge to construct multi-scale ordered structure in three-dimensional space.At the same time,the three-dimensional network constituting of nanofibers or nanotubes,is similar to the extracellular matrix and it is conducive to cell proliferation and growth.Therefore,they have great potential in the field of tissue engineering and biomedical.Three-dimensional porous materials are widely used in many fields because of their unique pore structure and corresponding properties.However,there are obvious disadvantages in the control of porous materials'structure and property by current method,such as pore structure distribution,pore size and others.In this paper,we focus on the construction and regulation of three-dimensional silica materials'structural and properties by combining the method of biomimetic mineralization,sol-gel with ice segregation induced self-assembly?ISISA?from one-dimensional silica nanotubes.We also investigated their properties and the possibility in medical dressings,nano-bioreactor and bone repair applications.The peptide I₃K can self-assemble into nanofibers in aqueous solutions in which a large amount of positive charges on the surface.These I₃K assemblies can act as catalyst for the hydrolysis and polycondensation of silica precursors and template for silica deposition.The peptide-silica hydrogel was formed via the control of the process of mineralization and gelation,in which the one-dimensional silica nanotubes were arranged into three-dimensional network structure similar to the extracellular matrix.The effects of the mechanical properties of the hydrogels were investigated by changing the reaction conditions of the samples,including the gelling time,the pH value of the solution,the concentration of the silicon source,the amount of ethanol and the concentration of the peptides.This exploratory work provides sufficient theoretical and experimental instruction for the preparation of organic-inorganic hybrid gel materials.We also explored their potential application in medical dressings from drugs loading and releasing behavior,moisture retention,the cytotoxicity and in vitro cell culture.The introduction of ISISA method makes it possible to prepare hydrogel with controlled three-dimensional structure.Firstly,the prepared hydrogel were pretreated,and then freeze at different cold sources.The ice was used as the template to make the silica nanotubes further arrange during the freezing process and finally three dimensional silica materials with porous structures can be obtained from one dimensional nanotubes.We regulated the pore size and distribution,wall thickness,morphology and orientation of pore by adjusting the freezing temperature,freezing direction,concentration of peptide and TEOS.Finally we explored the possible application as nano-bioreactor and bone tissue repair scaffolds.In this paper,we realized the preparation of three dimensional silica nano-materials from one-dimensional silica nanotubes through the combination of biomimetic mineralization,sol-gel and ISISA.The preparing processes are easy to operate and needn't the addition of other chemical reagents.Furthermore their unique structures and properties make them useful in the field of biocatalysis and tissue engineering.