Ultra-sensitive detection of Fusobacterium nucleatum with magnetic nanoparticle probe in dark-field

Abstract:

[Background] Fusobacterium nucleatum, an opportunistic pathogen causing infectious diseases, is a risk factor for the occurrence of colorectal cancer. Simple and rapid techniques are urgently needed for the detection of F. nucleatum in clinical practice. [Objective] In this study, we established a direct observation and counting method to count F. nucleatum cells in samples with magnetic nanoparticle (MNP) probe under dark-field microscopy. [Methods] We prepared the MNP probe by modifying MNPs with the homemade polyclonal antibodies against F. nucleatum, which can bind to F. nucleatum specifically. Furthermore, we compared the sensitivity of our method with that of real-time fluorescence quantitative PCR (qPCR) for detection of F. nucleatum. [Results] The method established in this study showed the limit of detection as low as 3.42×10¹ copies/μL and the sensitivity 5 times higher than that of qPCR. For detection of the real samples, the results of ounting F. nucleatum by our method are consistent with that by qPCR. [Conclusion] The established method is simple, rapid (within about 30 min), sensitive, and economical for detecting F. nucleatum, which has the potential to serve the detection of clinical samples.