Detection of Escherichia coli and Salmonella typhimurium Using Interdigitated Microelectrode Capacitive Immunosensors: The Importance of Transducer Geometry

Abstract

This paper presents an immunosensing system to detect Escherichia coli and Salmonella based on electrochemical impedance spectroscopy at interdigitated electrode structures. Our results show the importance of good electrode design in the final detection limit. Four different structures have been fabricated and functionalized. Biotinylated polyclonal antibodies have been immobilized on neutravidin-coated chips, and BSA has been used to avoid nonspecific adsorption. The immunosensor may be said to be capacitive since it is that part of the impedance used to monitor the presence of bacteria in phosphate buffer solution samples. Detection limits around 10(4)-10(5) cells mL(-1) have been reached using chips featuring interdigitated structures of less than 10 microm wide and 1.5 mm long. In both cases, the detection limits of the corresponding ELISA assays, using the same antibodies, was 1 order of magnitude higher (10(5)-10(6) cells mL(-1)). The analysis time, including sensor preparation was less than 5 h.

Amperometric detection of Enterobacteriaceae in river water by measuring β-galactosidase activity at interdigitated microelectrode arrays

“…Nevertheless, there is still room for performance improvements. For example, optimizing the geometry of the electrodes, such as reduction of the size of the fingers and/or gaps between them in the interdigitated electrodes, could contribute to improving the detection limit further [45]. Also, lower detection limits are possible if the incubation period is extended.…”

An Immunosensor for Pathogenic Staphylococcus aureus Based on Antibody Modified Aminophenyl-Au Electrode

“…Foods that are frequently incriminated in staphylococcal poisoning include meat and meat products, milk, and water. The toxic chemical released by S. aureus is enterotoxin that has been found to be produced at a hazardous level for 10 8 cells per kg of food [2]. Therefore rapid, sensitive, and reliable methods to detect foodborne pathogens are increasingly necessary in health care today.…”

“…Among biosensors, immunosensors are widely investigated for bacteria detection due to their specific advantages, such as high affinity and simple fabrication [6,7]. In the literature, many recent studies focus on E. coli and Salmonella bacteria detection with different transducing techniques: QCM [8], SPR [9], electrochemical techniques: capacitive [10] and amperometric measurements [11]. Although several electrochemical immunosensors for the detection of foodborne pathogenic bacteria have been reported in the literature, 2 ISRN Electrochemistry only a few of them have been used for the quantification of S. aureus [12][13][14].…”

An Electrochemical Enzyme Immunochip Based on Capacitance Measurement for the Detection of IgG

“…The degree of electrode membrane activation by enzyme can be estimated from the electrode signal in the presence of substrate. There have been, however, limited studies on this type of immunosensor coupled with capacitance or impedance measurement, [8][9][10] which may be due to difficulties in linking an enzyme reaction to a method for changing the impedance or capacitance of an electrode. McNeil et al introduced ability of sensor based on the measurement of impedance change by using polymer coatings on electrodes and analysis the antigen-antibody reaction qualitatively by immunostrips and quantitatively by EIS.…”