title: Comparison of sensing strategies in SPR biosensor for rapid and sensitive enumeration of bacteria.
abstract: Rapid and sensitive detections of microorganisms are very important for biodefence, food safety, medical diagnosis and pharmaceutics. The present study aims to find out the most proper bioactive surface preparation method to develop rapid, sensitive and selective bacteria biosensor, based on surface plasmon resonance (SPR) spectroscopy. Escherichia coli (E. coli) was used as a model bacterium and four sensing strategies in SPR were tested. Three of these strategies are antibody immobilization methods that are non-specific adsorption, specific adsorption via the avidin-biotin interaction, and immobilization of antibodies via self-assembled monolayer formation. The fourth strategy is a novel method for bacteria enumeration based on the combination of the SPR spectroscopy and immunomagnetic separation with using gold-coated magnetic nanoparticles. According to results, the most efficient SPR method is the one based on gold-coated magnetic nanoparticles. This method allows to specifically separate E. coli from the environment and to quantify rapidly without any labeling procedure. The developed method has a linear range between 30 and 3.0 × 10(4)cfu/ml, and a detection limit of 3 cfu/ml. The selectivity of the method was examined with Enterobacter aerogenes and Enterobacter dissolvens, which did not produce any significant response. The usefulness of the method to detect E. coli in real water samples was also investigated, and the results were compared with the results from plate-counting method. There was no significant difference between the methods (p>0.05).
authors.affiliation: Hacettepe University, Faculty of Engineering, Department of Food Engineering, Beytepe 06800 Ankara, Turkey.
authors.forename: Ozlem
authors.initials: O
authors.lastname: Torun
authors.forename: Ismail
authors.initials: I
authors.lastname: Hakkı Boyacı
authors.forename: Erhan
authors.initials: E
authors.lastname: Temür
authors.forename: Uğur
authors.initials: U
authors.lastname: Tamer
mesh_terms: D055910:Antibodies, Immobilized / Q000276:immunology; D004926:Escherichia coli / Q000276:immunology / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000175:diagnosis; D006801:Humans; D018189:Immunomagnetic Separation / Q000379:methods; D012680:Sensitivity and Specificity; D020349:Surface Plasmon Resonance / Q000191:economics / Q000379:methods*; D013997:Time Factors; D014871:Water Microbiology
chemical_list: D055910:Antibodies, Immobilized