Abstract
A great improvement in food safety and quality controls worldwide has been achieved through the development of biosensing platforms. Foodborne pathogens continue to cause serious outbreaks, due to the ingestion of contaminated food. The development of new, sensitive, portable, high-throughput, and automated platforms is a primary objective to allow detection of pathogens and their toxins in foods. Listeria monocytogenes is one common foodborne pathogen. Major outbreaks of listeriosis have been caused by a variety of foods, including milk, soft cheeses, meat, fermented sausages, poultry, seafood and vegetable products. Due to its high sensitivity and easy setup, electrochemical impedance spectroscopy (EIS) has been extensively applied for biosensor fabrication and in particular in the field of microbiology as a mean to detect and quantify foodborne bacteria. Here we describe a miniaturized, portable EIS platform consisting of a microfluidic device with EIS sensors for the detection of L. monocytogenes in milk samples, connected to a portable impedance analyzer for on-field application in clinical and food diagnostics, but also for biosecurity purposes. To achieve this goal microelectrodes were functionalized with antibodies specific for L. monocytogenes. The binding and detection of L. monocytogenes was achieved in the range 2.2 × 103 cfu/mL to 1 × 102 with a Limit of Detection (LoD) of 5.5 cfu/mL.
Highlights
Foodborne diseases include several illnesses resulting from ingestion of foods contaminated with microorganisms or chemicals
The binding and detection of L. monocytogenes was achieved in the range 2.2 × 103 cfu/mL to 1 × 102 with a Limit of Detection (LoD) of 5.5 cfu/mL
Nyquist related to incubation the incubation of different concentrations of Listeria monocytogenes the sensing layer with antibodies against the bacterium
Summary
Foodborne diseases include several illnesses resulting from ingestion of foods contaminated with microorganisms or chemicals. Outbreaks of listeriosis have been caused by a variety of foods, including milk, soft cheeses, meat, fermented sausages, poultry, seafood and vegetable products [5,6] This pathogen represents a potential risk to human health, since it is able to overcome food preservation and safety barriers, due to the adaptation and survival mechanisms allowing the persistence and growth in different environmental conditions (cold temperatures, low pH and high salt concentration) [7]. In this case impedance spectroscopy allows the characterization of solution/electrode interface and can be used to monitor the attachment of molecules [18,19] and cells [20,21] In this last reference, a gold interdigitated array microelectrode (IDAM) allowed the simultaneous detection of two different food pathogens [19]. Due to the high flexibility, predisposition to further miniaturization, and the possibility to improve the number of analytes and the ease of use, the developed device is competitive with currently used methods and can be used as the point-of-care device for clinical and food diagnostics, as well as for biosecurity purposes
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