title: Effects of surface functionalization on the surface phage coverage and the subsequent performance of phage-immobilized magnetoelastic biosensors.
abstract: One of the important applications for which phage-immobilized magnetoelastic (ME) biosensors are being developed is the wireless, on-site detection of pathogenic bacteria for food safety and bio-security. Until now, such biosensors have been constructed by immobilizing a landscape phage probe on gold-coated ME resonators via physical adsorption. Although the physical adsorption method is simple, the immobilization stability and surface coverage of phage probes on differently functionalized sensor surfaces need to be evaluated as a potential way to enhance the detection capabilities of the biosensors. As a model study, a filamentous fd-tet phage that specifically binds streptavidin was adsorbed on either bare or surface-functionalized gold-coated ME resonators. The surface functionalization was performed through the formation of three self-assembled monolayers with a different terminator, based on the sulfur-gold chemistry: AC (activated carboxy-terminated), ALD (aldehyde-terminated), and MT (methyl-terminated). The results, obtained by atomic force microscopy, showed that surface functionalization has a large effect on the surface phage coverage (46.8%, 49.4%, 4.2%, and 5.2% for bare, AC-, ALD-, and MT-functionalized resonators, respectively). In addition, a direct correlation of the observed surface phage coverage with the quantity of subsequently captured streptavidin-coated microbeads was found by scanning electron microscopy and by resonance frequency measurements of the biosensors. The differences in surface phage coverage on the differently functionalized surfaces may then be used to pattern the phage probe layer onto desired parts of the sensor surface to enhance the detection capabilities of ME biosensors.
authors.affiliation: Materials Engineering Program, Department of Mechanical Engineering, Auburn University, Auburn, AL 36849, USA. horiksh@auburn.edu
authors.forename: Shin
authors.initials: S
authors.lastname: Horikawa
authors.forename: Deepa
authors.initials: D
authors.lastname: Bedi
authors.forename: Suiqiong
authors.initials: S
authors.lastname: Li
authors.forename: Wen
authors.initials: W
authors.lastname: Shen
authors.forename: Shichu
authors.initials: S
authors.lastname: Huang
authors.forename: I-Hsuan
authors.initials: IH
authors.lastname: Chen
authors.forename: Yating
authors.initials: Y
authors.lastname: Chai
authors.forename: Maria L
authors.initials: ML
authors.lastname: Auad
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bozack
authors.forename: James M
authors.initials: JM
authors.lastname: Barbaree
authors.forename: Valery A
authors.initials: VA
authors.lastname: Petrenko
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Chin
mesh_terms: D001435:Bacteriophages / Q000502:physiology* / Q000648:ultrastructure; D001681:Biological Assay / Q000295:instrumentation*; D015374:Biosensing Techniques / Q000295:instrumentation*; D055119:Elastic Modulus; D004867:Equipment Design; D019544:Equipment Failure Analysis; D018189:Immunomagnetic Separation / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation*