Magnetoelastic Biosensors for Real-Time, Wireless Pathogen Detection on Surfaces

Recent outbreaks of Ebola in the United States have brought to the public’s attention the transfer of disease by contact with virus- and bacteria-contaminated surfaces ranging from hospital counters to door knobs to airplane seats. The need for a real-time, on-site technique by which pathogen-contaminated surfaces can be identified is immediate and real. Standard microbiological detection techniques, including enzyme-linked immunosorbent assay (ELSA), polymerase chain reaction (PCR) and plate count, are time-consuming and manpower-intensive. This paper describes research into wireless magnetoelastic (ME) biosensors combined with a surface-scanning coil that can be used to detect both viral and bacterial contamination of surfaces. This detection method takes less than 10 minutes and eliminates time-consuming sample preparation such as enrichment. This paper investigates the use of wireless ME biosensors for the surface-scanning detection of pathogens on surfaces. The ME biosensor consists of an ME resonator as the sensor platform and E2 phage as the bio-recognition element. The E2 phage is genetically engineered to specifically bind with Salmonella Typhimurium. The ME biosensor is actuated into mechanical resonance by an externally applied magnetic field. A microfabricated planar coil was used to measure the resonant frequency of multiple ME biosensors in real time. When this phage-coated ME biosensor comes into contact with Salmonella cells, the bacterial cells are captured and bound to the biosensor’s surface by the phage. The bound bacterial cells then cause the mass of the ME biosensor to increase, resulting in a decrease in the resonant frequency. The change of the resonant frequency is known to be directly proportional to the additional mass of the bacteria attached to the biosensor surface. As a model study, multiple E2 phage-coated biosensors (measurement sensors) were placed on surfaces spiked with Salmonella Typhimurium with various concentrations. Control sensors without phage were also used to compensate for environmental effects and non-specific binding. The limit of detection and repeatability of testing were found to be comparable to standard real-time PCR. In this manner, in-situ, continuous, real-time monitoring of pathogenic surface contamination can be performed on any surfaces.