Bio-inorganic Synthesis of ZnO Powders Using Recombinant His-tagged ZnO Binding Peptide as a Promoter
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Inorganic-binding peptides termed as genetically engineered polypeptides for inorganics (GEPIs), are small peptide sequences selected via combinatorial biology-based protocols of phage or cell surface display technologies. Recent advances in nanotechnology and molecular biology allow the engineering of these peptides with specific affinity to inorganics, often used as molecular linkers or assemblers, to facilitate materials synthesis, which provides a new insight into the material science and engineering field. As a case study on this biomimetic application, here we report a novel biosynthetic ZnO binding protein and its application in promoting bio-inorganic materials synthesis. In brief, the gene encoding a ZnO binding peptide(ZBP) was genetically fused with His6-tag and GST-tag using E.coli expression vector pET-28a (+) and pGEX-4T-3. The recombinant protein GST-His-ZBP was expressed, purified with Ni–NTA system, identified by SDS–PAGE electrophoresis and Western blot analysis and confirmed by liquid chromatography-mass spectrometry/mass spectrometry (LC–MS/MS) analysis. Affinity adsorption test demonstrated that the fusion protein had a specific avidity for ZnO nanoparticles (NPs). Results from the bio-inorganic synthesis experiment indicated that the new protein played a promoting part in grain refinement and accelerated precipitation during the formation of the ultra-fine precursor powders in the Zn(OH)2 sol. X-ray diffraction (XRD) analysis on the final products after calcining the precursor powders showed that hexagonal wurtzite ZnO crystals were obtained. Our work suggested a novel approach to the application about the organic–inorganic interactions.
KeywordsRecombinant technology Expression and purification Specific binding protein Biosorption Precursor precipitates Bio-inorganic synthesis
Genetically engineered polypeptide for inorganics
Transmission electron microscopy
Liquid chromatography-mass spectrometry/mass spectrometry
The authors thank Dr. Naomi Furnish Yamada for careful review of this manuscript. We appreciate unselfish assistance of Researcher Qi Lian Qin, Dr. Huan Zhang, and Dr. Qing Yang from the Institute of Zoology, Chinese Academy of Sciences. We are truly grateful to Dr. Peng Hu from Institute of Process Engineering for the generous presents of nanomateirals. We thank Mr. Xiaoming Li from the Institute of Zoology, Chinese Academy of Sciences for analysis of mass spectrometry. We would like to express our most sincere gratitude to research team of Professor Jianguo Chen for enormous guidance and help.