Sensitive detection of maltose and glucose based on dual enzyme-displayed bacteria electrochemical biosensor

Glucoamylase-displayed bacteria (GA-bacteria) and glucose dehydrogenase-displayed bacteria (GDH-bacteria) were co-immobilized on multi-walled carbon nanotubes (MWNTs) modified glassy carbon electrode (GCE) to construct GA-bacteria/GDH-bacteria/MWNTs/GCE biosensor. The biosensor was developed by optimizing the loading amount and the ratio of GA-bacteria to GDH-bacteria. The as prepared biosensor exhibited a wide dynamic range of 0.2-10 mM and a low detection limit of 0.1 mM maltose (S/N=3). The biosensor also had a linear response to glucose in the range of 0.1-2.0 mM and a low detection limit of 0.04 mM glucose (S/N=3). Interestingly, at the same concentration, glucose was 3.75-fold sensitive than that of maltose at the proposed biosensor. No interferences were observed for other possible mono- and disaccharides. The biosensor also demonstrated good long-term storage stability and repeatability. Further, using both GDH-bacteria/MWNTs/GCE biosensor and GA-bacteria/GDH-bacteria/MWNTs/GCE biosensor, glucose and maltose in real samples can be detected. Therefore, the proposed biosensor is capable of monitoring the food manufacturing and fermentation process. (C) 2016 Elsevier B.V. All rights reserved.