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

Abstract

Microbial safety of drinking water constitutes a major concern in countries at all levels of economic development. Thus, rapid, sensitive and cost effective methods of pathogenic bacteria detection, like common like Escherichia coli O157:H7, which can cause important diseases, is highly required. In this work an impedimetric transducer modified with E. coli specific aptamer is studied. To enhance the sensitivity a three-dimensional interdigitated electrode array (3D-IDEA) impedimetric transducer in which the electrodes separated by insulating barriers was used. In this sensor, chemical reactions at the surface of the barrier provoke electrical charge redistribution which causes changes in surface conductivity. A DNA aptamer that recognizes specifically the outer membrane proteins of the E. coli O157:H7 was selected as the biorecognition moiety. Here we report a novel label-free impedance aptasensor for detection and quantification of pathogenic E. coli O157:H7 with a low detection limit, good selectivity and short detection times. The developed sensor shows a linear response (R 2 =0.977), proportional to the logarithm of bacterial concentration present in the sample, with a limit of detection (LOD) of about 10 2 cfu•mL-1. No response was registered when the aptasensor was incubated with other bacterial strains, confirming the selectivity of suggested method. Additionally, the possibility of the sensor regeneration is shown, 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.

Microfluidic based impedance biosensor for pathogens detection in food products

“…Electrospun detection technique combined magnetic separation technique, capillary immunoassay, and direct electrical measurement for rapid and accurate sensing of the E. coli O157:H7 cells, the electrospun biosensor device has a linear detection for E. coli O157:H7 concentration of 10 1 to 10 4 CFU/mL with a low concentration of 67 CFU/mL . The impedimetric biosensor approach was implemented and studied (See Table ) by measuring the change in the impedance of the electrodes which indicates the presence or absence of the pathogen cells. These pathogen cells bind to the receptors such as antibodies that are immobilized on the interdigitated electrode arrays (IDEAs).…”

Polyadenine-mediated Immobilization of Aptamers on a Gold Substrate for the Direct Detection of Bacterial Pathogens

“…[29][30][31] Moreover, several groups had reported on the use of aptamers as probes for the detection of bacteria. [32][33][34] Consequently, in this work, an SPR biosensor for bacterial detection was fabricated simply by attaching polyA-containing aptamers on a planar gold substrate. The aptamers chosen here are specific to Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively.…”

Conjugated Molecule Based Sensor for Microbial Detection in Water with E. coli as a Case Study and Elucidation of Interaction Mechanism

“…The methods such as quartz crystal microbalance , impedance spectroscopy , electrochemical methods , fluorscence spectrometry , have been able to provide rapid detection of E. coli with time of about 5–120 minutes. In these methods, the sensing electrodes are modified with biomolecules such as antibodies , enzymes, peptides , proteins , aptamer that are specific to E. coli . These are multistep detection processes and biomolecules used in the process are expensive and should be carefully handled by experts.…”

“…Conjugated molecules designed for detection of live bacteria are less explored . Most of them are functionalized with biomolecules after which the bacteria are incubated for 30 min to 1 hour . In the present work, amine receptor based conjugated molecule is studied for detection of live E. coli .…”