Materials Research and Education Center, Auburn University, Auburn, AL 36849, USA.
J Food Prot. 2012 Apr;75(4):631-6. doi: 10.4315/0362-028X.JFP-11-339.
This article presents rapid, sensitive, direct detection of Salmonella Typhimurium on eggshells by using wireless magnetoelastic (ME) biosensors. The biosensor consists of a freestanding, strip-shaped ME resonator as the signal transducer and the E2 phage as the biomolecular recognition element that selectively binds with Salmonella Typhimurium. This ME biosensor is a type of mass-sensitive biosensor that can be wirelessly actuated into mechanical resonance by an externally applied timevarying magnetic field. When the biosensor binds with Salmonella Typhimurium, the mass of the sensor increases, resulting in a decrease in the sensor's resonant frequency. Multiple E2 phage-coated biosensors (measurement sensors) were placed on eggshells spiked with Salmonella Typhimurium of various concentrations (1.6 to 1.6 × 10(7) CFU/cm(2)). Control sensors without phage were also used to compensate for environmental effects and nonspecific binding. After 20 min in a humidity-controlled chamber (95%) to allow binding of the bacteria to the sensors to occur, the resonant frequency of the sensors was wirelessly measured and compared with their initial resonant frequency. The resonant frequency change of the measurement sensors was found to be statistically different from that of the control sensors down to 1.6 × 10(2) CFU/cm(2), the detection limit for this work. In addition, scanning electron microscopy imaging verified that the measured resonant frequency changes were directly related to the number of bound cells on the sensor surface. The total assay time of the presented methodology was approximately 30 min, facilitating rapid detection of Salmonella Typhimurium without any preceding sampling procedures.
本文提出了一种利用无线磁弹性（ME）生物传感器快速、灵敏、直接检测鸡蛋壳表面沙门氏菌 Typhimurium 的方法。生物传感器由独立的、条状 ME 谐振器作为信号转换器和 E2 噬菌体作为生物分子识别元件组成，E2 噬菌体选择性地与沙门氏菌 Typhimurium 结合。这种 ME 生物传感器是一种质量敏感型生物传感器，可以通过外部施加的时变磁场无线驱动进入机械共振。当生物传感器与沙门氏菌 Typhimurium 结合时，传感器的质量增加，导致传感器的共振频率降低。多个涂有 E2 噬菌体的生物传感器（测量传感器）被放置在涂有不同浓度沙门氏菌 Typhimurium 的鸡蛋壳上（1.6 到 1.6×10(7)CFU/cm(2)）。还使用了没有噬菌体的对照传感器来补偿环境影响和非特异性结合。在湿度控制的腔室（95%）中放置 20 分钟，以允许细菌与传感器结合，然后无线测量传感器的共振频率，并将其与初始共振频率进行比较。发现测量传感器的共振频率变化与对照传感器的共振频率变化在 1.6×10(2)CFU/cm(2)以下具有统计学差异，这是该工作的检测限。此外，扫描电子显微镜成像证实了所测量的共振频率变化与传感器表面结合的细胞数量直接相关。所提出的方法的总测定时间约为 30 分钟，便于在无需任何预先采样程序的情况下快速检测沙门氏菌 Typhimurium。
