Effect of Silver Nanoparticles on the Electron Transfer Reactivity and the Catalytic Activity of Myoglobin

Authors

  • Xin Gan,

    1. Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, P. R. China, Fax: (+86) 25-835-92510
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  • Tao Liu,

    1. Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, P. R. China, Fax: (+86) 25-835-92510
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  • Jun Zhong,

    1. Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, P. R. China, Fax: (+86) 25-835-92510
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  • Xinjian Liu,

    1. Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, P. R. China, Fax: (+86) 25-835-92510
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  • Genxi Li Prof. Dr.

    1. Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, P. R. China, Fax: (+86) 25-835-92510
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Abstract

Silver nanoparticles (11±1.5 nm) could greatly enhance the electron-transfer reactivity of myoglobin (Mb) and its catalytic ability toward hydrogen peroxide (H2O2). Direct fast electron transfer between Mb and a pyrolytic graphite (PG) electrode was achieved, and a pair of well-defined, quasireversible redox peaks was obtained. The cathodic and anodic peaks were located at −329 and −281 mV, respectively. Meanwhile, the catalytic ability of the protein toward the reduction of H2O2 was also studied, and a H2O2 biosensor was subsequently fabricated. Its detection limit was 1.0×10−6M with a sensitivity of 0.0205 μA per μM of H2O2. The apparent Michaelis–Menten constant was calculated to be 1303 μM. Flocculation assay showed that the protein maintained plasmon layers surrounding the surface of silver nanoparticles and avoided silver-nanoparticle aggregation. On the other hand, UV-visible spectroscopy studies revealed that silver nanoparticles could induce a small change of the heme-group environment of the protein; this contributed to the enhancement of the electron-transfer reactivity and the catalytic activity.

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