Extracellular Bacterial Synthesis of Protein-Functionalized Ferromagnetic Co3O4 Nanocrystals and Imaging of Self-Organization of Bacterial Cells under Stress after Exposure to Me

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• 作者：Umesh Kumar ; Ashvini Shete ; Arti S. Harle ; Oksana Kasyutich ; W. Schwarzacher ; Archana Pundle ; Pankaj Poddar
• 刊名：Chemistry of Materials
• 出版年：2008
• 出版时间：February 26, 2008
• 年：2008
• 卷：20
• 期：4
• 页码：1484 - 1491
• 全文大小：1554K
• 年卷期：v.20,no.4(February 26, 2008)
• ISSN：1520-5002

文摘

Co₃O₄, which crystallizes in the spinel phase at temperatures much higher than ambient temperatures, orders antiferromagnetically below its Neel temperature (~40 K). However, in nanosize, it shows ferromagnetic ordering due to surface canting, disorder, imperfect oxygen atom coordination, etc. Here, for the first time, we report the synthesis of single-crystalline, ferromagnetic Co₃O₄ nanoparticles functionalized with proteins (size 5–7 nm) using cobalt acetate as precursor at room temperature in aqueous medium by a metal-tolerant marine bacterium isolated from the coast of the Arabian Sea. Energetically unfavorable change in the oxidation state of Co atoms from (+2 to +3) during synthesis by the bacterial strain was evidenced by X-ray photoelectron spectroscopy. The effect on the morphology of bacterial cells after exposure to the cobalt acetate was imaged by scanning electron microscopy showing cooperative, self-organized, structured colony formation, possibly due to the interbacterial communication under external stress.