Publication details
Immunosensing of pathogens using piezoelectric, electrochemical and surface plasmon resonance based transducers
| Authors | |
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| Year of publication | 2017 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Rapid detection of low levels of bacteria remains challenging for point-of-care clinical diagnosis, food testing and environmental screening. Our research focused on Salmonella enterica var. Typhimurium, which belongs to leading agents of gastrointestinal diseases; humans become infected particularly by consumption of contaminated food such as meat, eggs and unpasteurized dairy products. A label-free immunosensing employed screen-printed sensors combined with electrochemical impedance spectroscopy, piezoelectric quartz crystal microbalance (QCM) and surface plasmon resonance (SPR / Biacore, BioNavis). Specific antibody was covalently immobilized either directly to gold (cysteamine monolayer and glutaraldehyde) or through carboxymethylated dextran layers (EDC/NHS activation). These approaches provided limits of detection at 1000 CFU/mL within 10-20 min, with negligible interference from other bacteria. To improve sensitivity, signal enhancement was carried out using labelling of the captured microbes with secondary antibody-peroxidase conjugate. Afterwards, substrate mixture consisting of H2O2 and 4-chloro-1-naphthol formed insoluble benzo-4-chlorocyclohexadienone which precipitated on the sensingsurface and provided excellent signal amplification. In this way, 100 CFU/ml of S. Typhimurium were detectable. Several variants of immunosensors were compared, including evaluation on milk samples. Different ways for sample treatment (combinations of heat and sonication) were tested and their impact on the performance was evaluated. Atomic force microscopy was used to study the effect of the treatment on the cell shape and to confirm the specific binding of microbes to the sensing surface, cells were visible even on the rough screen-printed surfaces. AFM images and height profiles also helped to quantify effect of the precipitating product generated by the enzyme label on the improved performance of immunosensors. |
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