title: Diazonium-based impedimetric aptasensor for the rapid label-free detection of Salmonella typhimurium in food sample.
abstract: Fast and accurate detection of microorganisms is of key importance in clinical analysis and in food and water quality monitoring. Salmonella typhimurium is responsible for about a third of all cases of foodborne diseases and consequently, its fast detection is of great importance for ensuring the safety of foodstuffs. We report the development of a label-free impedimetric aptamer-based biosensor for S. typhimurium detection. The aptamer biosensor was fabricated by grafting a diazonium-supporting layer onto screen-printed carbon electrodes (SPEs), via electrochemical or chemical approaches, followed by chemical immobilisation of aminated-aptamer. FTIR-ATR, contact angle and electrochemical measurements were used to monitor the fabrication process. Results showed that electrochemical immobilisation of the diazonium-grafting layer allowed the formation of a denser aptamer layer, which resulted in higher sensitivity. The developed aptamer-biosensor responded linearly, on a logarithm scale, over the concentration range 1 × 10(1) to 1 × 10(8)CFU mL(-1), with a limit of quantification (LOQ) of 1 × 10(1) CFU mL(-1) and a limit of detection (LOD) of 6 CFU mL(-1). Selectivity studies showed that the aptamer biosensor could discriminate S. typhimurium from 6 other model bacteria strains. Finally, recovery studies demonstrated its suitability for the detection of S. typhimurium in spiked (1 × 10(2), 1 × 10(4) and 1 × 10(6) CFU mL(-1)) apple juice samples.
authors.affiliation: Biosensors and Bioelectronics Centre, Department of Physics, Chemistry and Biology (IFM), Linkoping University, 58183 Linkoping, Sweden; Eletroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Bagheryan
authors.affiliation: Eletroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
authors.forename: Jahan-Bakhsh
authors.initials: JB
authors.lastname: Raoof
authors.affiliation: Biosensors and Bioelectronics Centre, Department of Physics, Chemistry and Biology (IFM), Linkoping University, 58183 Linkoping, Sweden.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Golabi
authors.affiliation: Biosensors and Bioelectronics Centre, Department of Physics, Chemistry and Biology (IFM), Linkoping University, 58183 Linkoping, Sweden.
authors.forename: Anthony P F
authors.initials: APF
authors.lastname: Turner
authors.affiliation: Biosensors and Bioelectronics Centre, Department of Physics, Chemistry and Biology (IFM), Linkoping University, 58183 Linkoping, Sweden. Electronic address: valerio.beni@acreo.se.
authors.forename: Valerio
authors.initials: V
authors.lastname: Beni
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry; D015374:Biosensing Techniques; D003979:Diazonium Compounds / Q000737:chemistry; D055664:Electrochemical Techniques; D005516:Food Microbiology; D006801:Humans; D057230:Limit of Detection; D012486:Salmonella typhimurium / Q000302:isolation & purification* / Q000472:pathogenicity
chemical_list: D052157:Aptamers, Nucleotide; D003979:Diazonium Compounds
keywords: Aptamer; Diazonium grafting; Electrochemical impedance spectroscopy; Food analysis; Label-free detection; S. typhimurium