Chloroform-Treated Filamentous Phage as a Bioreceptor for Piezoelectric Sensors

摘要

Affinity-selected filamentous bacteriophage was induced to spherical forms ('spheroids') by chloroform treatment and deposited to piezoelectric transducers by Langmuir-Blodgett to prepare biosensors for the detection of streptavidin and S. typhimurium. ELISA confirmed affinity-selected phage specificity for streptavidin. Spheroid induction was optimized to achieve greatest conversion yields as a function of solvent exposure time and concentration. Results from whole-virion agarose gel electrophoresis indicated 27-fold phage aqueous dilutions mixed with equal volumes of chloroform for 60 s at room temperature was adequate. Phage conversion to spheroids with subsequent binding to S. typhimurium was confirmed by transmission electron microscopy. Spheroids for streptavidin and S. typhimurium prepared as either pure monolayers of phage coat proteins or proteins reconstituted with phospholipids were evaluated by isotherm, elasticity, and transfer ratio analysis. Results showed that spheroids combined with phospholipids produced a phage coat monolayer possessing higher elasticity and transfer ratios than monolayers of phage coat proteins alone, resulting in spatially superior deposition to substrates and subsequent firm binding of S. typhimurium that followed mass theory for piezoelectric transducers. Scanning electron microscopy confirmed binding of streptavidin-coated beads and S. typhimurium to prepared biosensors. In summary, spheroid-based sensors could be an effective analytical method for detecting and monitoring quantitative changes of bacterial agents under any conditions that warrant their recognition.