Rapid Detection of Bifidobacterium bifidum in Feces Sample by Highly Sensitive Quartz Crystal Microbalance Immunosensor

Abstract

In this work, a quartz crystal microbalance (QCM) sensor has been fabricated using immunoassay for sensitive determination of <i>Bifidobacterium bifidum</i>. Au nanoparticle has been used for amplifying sandwich assays. The proposed immunosensor exhibited a linear detection range between 10³ and 10⁵ CFU/mL with a limit of detection of 2.1 × 10² CFU/mL. The proposed immunosensor exhibited good selectivity for <i>B. bifidum</i> sensing with low cross reactivity for other foodborne pathogens such as <i>Lactobacillus acidophilus, Listeria monocytogenes</i>, and <i>Escherichia coli</i>. In addition, the proposed immunosensor has been successfully used for <i>B. bifidum</i> detection in feces samples and food samples. The frequency decreases of 12, 17, and 10 Hz were observed from the milk samples consisting of the mixtures of <i>L. acidophilus, L. monocytogenes</i>, and <i>E. coli</i>. The frequency decreases of 8, 15, and 7 Hz were observed from the feces samples consisting of the mixtures of <i>L. acidophilus, L. monocytogenes</i>, and <i>E. coli</i>.