Early detection of foodborne pathogens is significant for ensuring food safety. Nowadays, the detection of pathogens found in food can take up to 72 h and it might take a week to confirm a positive sample. While standardized methods give test results in a shorter period, the reoccurring costs for each measurement are high. Therefore, it is necessary to develop technology that will be low-cost, fast, simple and accurate enough. Biosensors in combination with nucleic acid aptamers offer such possibilities. This work is focused on the development and testing of a biosensor based on DNA aptamers for detection of pathogenic bacteria Listeria innocua using the method of multi-harmonic quartz crystal microbalances (QCM). The aptasensor was prepared on the surface of a piezo crystal, whose frequency was affected by deposited mass. An aptamer specific to the genus Listeria spp. was used for the detection of this pathogen, which includes 16 subspecies, out of which 3 are excluded as their antigen structure differs from other species (L. murrayi, L. grayi, L. ivanovii). We found that addition of the pathogens at the surface of QCM transducer modified by aptamers resulted in the decrease of the resonant frequency in concentration depending manner. We also confirmed the specificity of the aptamer used for Listeria innocua, as neglected response of the sensor took place for E. coli for which Listeria spp. has some partial antigens identical and thus can cause cross-reactions in serological tests. The developed aptasensor showed promising sensitivity and specificity for real-time detection of Listeria innocua, with a detection time of 30 min. The achieved limit of detection was approximately 1.6 × 103 CFU/mL.
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