Rapid and sensitive biosensor for Salmonella

Abstract

The rapid and sensitive detection of Salmonella typhymurium based on the use of a polyclonal antibody immobilized by the Langmuir-Blodgett method on the surface of a quartz crystal acoustic wave device was demonstrated. The binding of bacteria to the surface changed the crystal resonance parameters; these were quantified by the output voltage of the sensor instrumentation. The sensor had a lower detection limit of a few hundred cells/ml, and a response time of B 100 s over the range of 10 2 -10 10 cells/ml. The sensor response was linear between bacterial concentrations of 10 2 -10 7 cells/ml, with a sensitivity of 18 mV/decade. The binding of bacteria was specific with two binding sites needed to bind a single cell. The sensors preserve 75% of their sensitivity over a period of 32 days.

Immunoassay for troponin I using a glassy carbon electrode modified with a hybrid film consisting of graphene and multiwalled carbon nanotubes and decorated with platinum nanoparticles

“…If n = 1, no cooperativity is observed and each binding site functions independently [35]. The n = 0.23 found in the present case corresponds to a negative cooperativity, which indicates the binding of cTnI to more than one anti-cTnI at the bioelectrode surface [36]. This may be due to the inhibition of multiple cTnI molecules binding to small aggregates or clusters of anti-cTnI due to steric hindrance [37].…”

Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria

“…Prepare phage monolayer onto LB subphase solution by allowing 300 μl aliquot of phage 12600 aqueous suspension (10 11 PFU/ml) to run down an inclined wettable glass rod that is partially submersed into the subphase 22,23 . 7.…”

Recognition of cell-specific binding of phage display derived peptides using an acoustic wave sensor

“…Biotinylated peptide (ASSLNIAGGGSK-Biotin) was coupled with the phospholipid via streptavidin/biotin binding. The stable LB film [5] of biotinylated monolayers was treated for 2 h with streptavidin, diluted to a final concentration of 0.01 mg/ml in the subphase solution [5], rinsed with distilled water, and dried for 2 min in ambient air. Then, the film was treated with the biotinylated peptide (0.001 mg/ml) in subphase solution for 2 h, rinsed and dried again as above.…”

“…Measurements were carried out using a PM-700 Maxtek plating monitor as previously described [5]. One ml PBS was delivered to the dry sensor surface and voltage was recorded for 4-8 min.…”

“…For each vesicle concentration the sensor signal approaches a steady-state value, corresponding to that concentration within 100 s (~2= 70 9 20 s). The response curves are distinguished by the fast reaction, the attainment of a steady state, and low non-specific binding [5].…”