Phage Fusion Proteins As Bioselective Receptors For Piezoelectric Sensors

Filamentous phage affinity-selected for streptavidin and Salmonella typhimurium from phage display libraries were transformed with chloroform into spherical forms then deposited as phage coat protein monolayers to quartz crystal microbalances (QCM) by Langmuir-Blodgett (LB) to prepare bioselective sensors. Maximum yield of spheroids was achieved by mixing 8.3 x 10-11 to 2.5 x 10-12 filamentous phage virions/ml with 1 ml chloroform for 60 seconds. Spheroid conversion and binding to S. typhimurium was confirmed by transmission electron microscopy. Phage coat monolayers incorporating phospholipid possessed high elasticity and transference to QCM substrates comparable to antibodies. Sensor responses to increasing concentrations of target analytes were characterized by rapid reaction, steady-state equilibrium, high sensitivity, and linear dose-response that followed mass theory for piezoelectric transducers. Scanning electron microscopy confirmed binding of target analytes to biosensors compared to controls. Phage-based sensors may allow detection of bacterial agents such as S. typhimurium in food safety and security applications.