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Chloroplasts-mediated biosynthesis of nanoscale Au-Ag alloy for 2-butanone assay based on electrochemical sensor

Yixia Zhang1, Guo Gao1, Qirong Qian2 and Daxiang Cui1*

Author Affiliations

1 Department of Bio-Nano-Science and Engineering, National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of Ministry of Education, Institute of Micro-Nano Science and Technology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, People’s Republic of China

2 Department of Orthopaedics, Changzheng Hospital affiliated to Second Military Medical University, 451 Fengyang Road, Shanghai, 20003, People’s Republic of China

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Nanoscale Research Letters 2012, 7:475  doi:10.1186/1556-276X-7-475

Published: 23 August 2012


We reported a one-pot, environmentally friendly method for biosynthesizing nanoscale Au-Ag alloy using chloroplasts as reducers and stabilizers. The prepared nanoscale Au-Ag alloy was characterized by UV–visible spectroscopy, X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM). Fourier transform infrared spectroscopy (FTIR) analysis was further used to identify the possible biomolecules from chloroplasts that are responsible for the formation and stabilization of Au-Ag alloy. The FTIR results showed that chloroplast proteins bound to the nanoscale Au-Ag alloy through free amino groups. The bimetallic Au-Ag nanoparticles have only one plasmon band, indicating the formation of an alloy structure. HR-TEM images showed that the prepared Au-Ag alloy was spherical and 15 to 20 nm in diameter. The high crystallinity of the Au-Ag alloy was confirmed by SAED and XRD patterns. The prepared Au-Ag alloy was dispersed into multiwalled carbon nanotubes (MWNTs) to form a nanosensing film. The nanosensing film exhibited high electrocatalytic activity for 2-butanone oxidation at room temperature. The anodic peak current (Ip) has a linear relationship with the concentrations of 2-butanone over the range of 0.01% to 0.075% (v/v), when analyzed by cyclic voltammetry. The excellent electronic catalytic characteristics might be attributed to the synergistic electron transfer effects of Au-Ag alloy and MWNTs. It can reasonably be expected that this electrochemical biosensor provided a promising platform for developing a breath sensor to screen and pre-warn of early cancer, especially gastric cancer.

Chloroplasts; Au-Ag alloy; Nanosensing film