The Effect of Phage Solution Chemistry on the Spore Binding Affinity of Magnetoelastic Biosensors

This paper presents the results of a study that investigates the effect of salt concentration on the immobilization of phages during the fabrication of magnetoelastic (ME) biosensors for the detection of Bacillus anthracis spores. The concentration of salt in the solution used to deposit and immobilize the phage is found to alter phage bundling characteristics and, hence, influence the ability of the biosensor to bind spores. ME biosensors were fabricated using different salt concentrations in the phage solution, and were then exposed to solutions containing known amounts of B. anthracis spores. The frequency response curves of the ME biosensors, were then measured to determine the effects of salt concentration on the sensors´ performance. Scanning electron microscopy (SEM) was used to confirm and quantify the binding of B. anthracis spores to the phage-coated ME biosensors. Transmission electron microscopy (TEM) was used to verify the structure of phage under different salt concentrations. Results showed that moderate concentrations of salt (420 mM NaCl) in the phage solution results in an optimal distribution of immobilized phages on the sensor surface and, hence, better binding of spores to the biosensor.