Phage coated magnetoelastic micro-biosensors for real-time detection of Bacillus anthracis spores

A micro-scale, freestanding, magnetoelastic biosensor coated with phage has been developed for the real-time in vitro detection of Bacillus anthracis spores. The sensor exhibits a characteristic resonance frequency upon the application of an alternating external magnetic field. It has a high sensitivity to the change in mass when spores are attached. The frequency versus mass sensitivity increases significantly with a decrease in sensor length. Spore detection is realized by measuring the resonance frequency change due to the change in mass as spores are captured onto the sensor surface. B. anthracis spore suspensions in a range of concentration levels (5 × 101 to 5 × 108 spores/ml) was tested using a 1000 μm × 200 μm × 15 μm sensor in a flowing fluid at a flow rate of 40 μl/min. The binding kinetics was analyzed based on the attachment rate. The specificity of the sensor to B. anthracis spores was examined compared with other Bacillus species.