| Summary: | Bacteria in the genus <i>Brucella</i> are the cause of brucellosis in humans and many domestic and wild animals. A rapid and culture-free detection assay to detect <i>Brucella</i> in clinical samples would be highly valuable. Nanomaterial optical fiber biosensors (NOFS) are capable of recognizing DNA hybridization events or other analyte interactions with high specificity and sensitivity. Therefore, a NOFS assay was developed to detect <i>Brucella</i> DNA from cultures and in tissue samples from infected mice. An ionic self-assembled multilayer (ISAM) film was coupled to a long-period grating optical fiber, and a nucleotide probe complementary to the <i>Brucella</i> IS<i>711</i> region and modified with biotin was bound to the ISAM by covalent conjugation. When the ISAM/probe duplex was exposed to lysate containing ≥100 killed cells of <i>Brucella</i>, or liver or spleen tissue extracts from <i>Brucella-</i>infected mice, substantial attenuation of light transmission occurred, whereas exposure of the complexed fiber to non-<i>Brucella</i> gram-negative bacteria or control tissue samples resulted in negligible attenuation of light transmission. Oligonucleotide probes specific for <i>B. abortus</i>, <i>B. melitensis</i>, and <i>B. suis</i> could also be used to detect and differentiate these three nomenspecies. In summary, the NOFS biosensor assay detected three nomenspecies of <i>Brucella</i> without the use of polymerase chain reaction within 30 min and could specifically detect low numbers of this bacterium in clinical samples.
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