A sensitive electrochemical aptasensor based on MB-anchored GO for the rapid detection of Cronobacter sakazakii

Abstract

Cronobacter sakazakii (C. sakazakii) can cause extremely high mortality diseases especially in infants, so it is necessary to rapidly and specifically detect C. sakazakii in powdered infant formula (PIF). In this work, the amplification strategy of methylene blue (MB)-anchored graphene oxide (GO) was used to develop an electrochemical aptasensor for detecting C. sakazakii easily and quickly. In the absence of C. sakazakii, GO would be bound to the aptamer of C. sakazakii by π-π interaction, and then adsorbed MB through electrostatic adherence; thus, the electrochemical signal of MB amplified. While in the presence of C. sakazakii, the bacteria would be specifically combined with the aptamer, and hindered the electrostatic adsorption of GO and MB to the aptamer, resulting in the decreasing electrochemical signal of MB. The fabricated electrochemical aptasensor showed a wide linear range from 2 × 101 to 2 × 106 CFU mL−1 of the bacteria concentration, and its limit of detection reached 7 CFU mL−1 (S/N = 3). In addition, the applicability of the aptasensor in PIF for the analysis of C. sakazakii was successfully demonstrated. This aptasensor would provide a new method for the detection of C. sakazakii but also a novel sensing platform for the rapid detection of pathogen bacteria.