High-sensitivity bacterial detection using biotin-tagged phage and quantum-dot nanocomplexes

doi:10.1073/pnas.0601211103

High-sensitivity bacterial detection using biotin-tagged phage and quantum-dot nanocomplexes

*National Cancer Institute,
^¶National Institutes of Health, Bethesda, MD 20892;
^†Optical Technology Division, Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899;
^‡Department of Molecular Genetics and Biotechnology, Hebrew University–Hadassah Medical School, Jerusalem 91120, Israel;
^§Ambion, Inc., Austin, TX 78744-1832; and
^‖SAIC Frederick, National Cancer Institute, Frederick, MD 21702

Contributed by Sankar Adhya, February 13, 2006

Abstract

With current concerns of antibiotic-resistant bacteria and biodefense, it has become important to rapidly identify infectious bacteria. Traditional technologies involving isolation and amplification of the pathogenic bacteria are time-consuming. We report a rapid and simple method that combines in vivo biotinylation of engineered host-specific bacteriophage and conjugation of the phage to streptavidin-coated quantum dots. The method provides specific detection of as few as 10 bacterial cells per milliliter in experimental samples, with an ≈100-fold amplification of the signal over background in 1 h. We believe that the method can be applied to any bacteria susceptible to specific phages and would be particularly useful for detection of bacterial strains that are slow growing, e.g., Mycobacterium, or are highly infectious, e.g., Bacillus anthracis. The potential for simultaneous detection of different bacterial species in a single sample and applications in the study of phage biology are discussed.

Footnotes

**To whom correspondence should be addressed at:
Laboratory of Molecular Biology, National Cancer Institute, 37 Convent Drive, Building 37, Room 5138, Bethesda, MD 20892-4264.
E-mail: sadhya{at}helix.nih.gov
Author contributions: R.E., M.M., J.H., A.B.O., G.G., C.M., and S.A. designed research; R.E., M.M., J.H., and K.N. performed research; R.E., M.M., J.H., A.B.O., R.A.F., G.G., C.M., and S.A. analyzed data; and M.M. and J.H. wrote the paper.
Conflict of interest statement: No conflicts declared.
Abbreviations:

QD,

quantum dots;

BLP,

biotin–ligase protein;

TEM,

transmission electron microscope/microscopy.