Novel impedimetric aptasensor for label-free detection of Escherichia coli O157:H7

Here we report a novel label-free impedimetric aptasensor for detection and quantification of pathogenic E. coli O157:H7 with a low detection limit, good selectivity and short detection time. The developed sensor shows a linear response (R2 = 0.977), proportional to the logarithm of bacterial concentration present in the sample, with the limit of detection (LOD) of about 102 cfu mL−1. No response of the aptasensor was registered in the presence of other bacterial strains (E. coli k12, Salmonella typhimurium, Staphylococcus aureus), which confirms the selectivity of the suggested detection method. Additionally, the methodology of the aptasensor regeneration was developed, so that the detection may be performed several times with the same sensor. Moreover, suitability of the aptasensor for bacteria detection in real samples was demonstrated with a new approach involving bacteria pre-concentration.