title: Rapid and sensitive magnetoelastic biosensors for the detection of Salmonella typhimurium in a mixed microbial population.
abstract: In this article, we report the results of an investigation into the performance of a wireless, magnetoelastic biosensor designed to selectively detect Salmonella typhimurium in a mixed microbial population. The Langmuir-Blodgett (LB) monolayer technique was employed for antibody (specific to Salmonella sp.) immobilization on rectangular shaped strip magnetoelastic sensors (2 x 0.4 x 0.015 mm). Bacterial binding to the antibody on the sensor surface changes the resonance parameters, and these changes were quantified as a shift in the sensor's resonance frequency. Response of the sensors to increasing concentrations (5 x 10(1) to 5 x 10(8) cfu/ml) of S. typhimurium in a mixture of extraneous foodborne pathogens (Escherichia coli O157:H7 and Listeria monocytogenes) was studied. A detection limit of 5 x 10(3) cfu/ml and a sensitivity of 139 Hz/decade were observed for the 2 x 0.4 x 0.015 mm sensors. Binding kinetics studies have shown that the dissociation constant (K(d)) and the binding valencies for water samples spiked with S. typhimurium was 435 cfu/ml and 2.33 respectively. The presence of extraneous microorganisms in the mixture did not produce an appreciable change in the biosensor's dose response behavior.
authors.affiliation: Materials Research and Education Center, Auburn University, Auburn, AL 36849, USA.
authors.forename: R
authors.initials: R
authors.lastname: Guntupalli
authors.forename: R S
authors.initials: RS
authors.lastname: Lakshmanan
authors.forename: J
authors.initials: J
authors.lastname: Hu
authors.forename: T S
authors.initials: TS
authors.lastname: Huang
authors.forename: J M
authors.initials: JM
authors.lastname: Barbaree
authors.forename: V
authors.initials: V
authors.lastname: Vodyanoy
authors.forename: B A
authors.initials: BA
authors.lastname: Chin
mesh_terms: D000907:Antibodies, Bacterial / Q000378:metabolism; D001431:Bacteriological Techniques / Q000379:methods*; D015374:Biosensing Techniques / Q000379:methods*; D019453:Escherichia coli O157 / Q000302:isolation & purification; D007700:Kinetics; D008089:Listeria monocytogenes / Q000302:isolation & purification; D012486:Salmonella typhimurium / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D000907:Antibodies, Bacterial