Detection of Bacillus Anthracis Spores Using Magnetostrictive Microcantilever-based Biosensor
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0951-E05-04
Detection of Bacillus Anthracis Spores Using Magnetostrictive Microcantilever-Based Biosensor Liling Fu, Suiqiong Li, Kewei Zhang, and Z.-Y. Cheng Materials Research and Education Center, Auburn University, Auburn, AL, 36849 ABSTRACT Recently, the magnetostrictive microcantilever (MSMC) as a high performance biosensor platform was introduced. The MSMC is a wireless acoustic wave (AW) sensor and exhibits a high Q value. More importantly, the MSMC works well in liquid. In this paper, the detection of Bacillus anthracis spores using MSMCs with filamentous phage as the bioprobe is reported. The phage-coated MSMC biosensors were exposed to cultures containing target spores with increasing concentrations ranging from 5 x 104 to 5 x 108 spores/mL. By monitoring the shift in the resonance frequency of the MSMCs, the spores were detected in a real-time manner and a detection limit of 105 spores/mL was obtained for the MSMCs used in this research. Higher sensitivity is expected for the MSMCs with smaller size. INTRODUCTION From last decade, intensive research has been conducted on developing high performance biosensor platforms based on the MEMS-based microcantilevers (MCs) [1-3]. As an AW device, MCs has many advantages over other AW devices, such as compact size and easy integration with analysis circuit and low cost. More importantly, the sensitivity of MCs was superior to that of traditional AW transducers. For example, B. Ilic et.al, demonstrated that silicon MCs are capable to detect a single E.coli bacterium, and to detect a mass in attogram (10-18) [4, 5]. Similar as all the AW devices, the MCs are operated based on the principle that the resonance frequency of the AW device changes with the mass load. For developing a biosensor, a biological receptor layer, such as antibody and phage, is usually immobilized on the AW device surface to react with the target species [6, 7]. The target biological species captured by the recognizers cause a change in the sensor surface, such as the mass or elastic property. The presence of the target species can be detected by monitoring the shift in the resonance frequency. At present, MCs as biosensor platforms focus primarily on two types: silicon-based MCs and piezoelectric MCs [1-5]. Recently, we introduced a novel type of MC, magnetostrictive microcantilever (MSMC), as the biosensor platform [8]. The MSMC employs magnetostrictive materials as the actuating layer. Due to the magnetic and magnetostrictive effects, the MSMC can be driven and sensed wirelessly. This is the principal advantage of MSMCs over other MCs. Moreover, the MSMCs exhibit a high Q value. It has been shown that the MSMCs worked well in both air and liquid [8]. Combined with a biological recognition element, MSMC can provide rapid, sensitive and simple biological detection. Bacillus anthracis spore is a fatal bio-threat agent. Prevention of diseases caused by B. anthracis spores depends on quickly detection and control of the pathogenic spores in the environment. Although conventional method is very se
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