nanotehnoloogia, nanoteknologia, nanotechnologija, nanotehnologijas, nanoteknologija,
nanotechnologii, nanotecnologia, nanotehnologijo, nanoteknik
Nano Geneeskunde...Nano Medicína
A rapid method for detecting and identifying very small numbers of diverse
bacteria, from anthrax to E. coli , has been developed by scientists from the
National Cancer Institute (NCI) and National Institute of Standards and Technology
(NIST). Described in the March 28 issue of Proceedings of the National Academy
of Sciences ,* the work could lead to the development of handheld devices for
accelerated identification of biological weapons and antibiotic-resistant or
virulent strains of bacteria—situations where speed is essential.
Traditional ways of identifying infectious bacteria and their possible treatments
can be time consuming and laborious, requiring the isolation and growth of the
bacteria over many hours or even days. The new method speeds up the process by
using fast-replicating viruses (called bacteriophages or phages) that infect
specific bacteria of interest and are genetically engineered to bind to "quantum
dots." Quantum dots are nanoscale semiconductor particles that give off stronger
and more intense signals than conventional fluorescent tags and also are more
stable when exposed to light. The method detects and identifies 10, or fewer,
target bacterial cells per milliliter of sample in only about an hour.
The phages were genetically engineered to produce
a specific protein on their surface. When these phages
infect bacteria and reproduce, the bacteria burst
and release many phage progeny attached to biotin
(vitamin H), which is present in all living cells.
The biotin-capped phages selectively attract specially
treated quantum dots, which absorb light efficiently
over a wide frequency range and re-emit it in a single
color that depends on particle size. The resulting
phage-quantum dot complexes can be detected and counted
using microscopy, spectroscopy or flow cytometry,
and the results used to identify the bacteria. The
new method could be extended to identify multiple
bacterial strains simultaneously by pairing different
phages with quantum dots that have different emission
The new method is more sensitive than conventional optical methods. It can
count how many viruses are infecting a single bacteria cell and how many quantum
dots are attached to a single virus. A provisional patent application was filed
originally through NIST, and a non-provisional patent application was filed
more recently through the National Institutes of Health, the parent agency
of NCI. The NIST contributions to the work include experimental design and
fluorescence imaging. Other authors are from NCI, NIH, SAIC-Frederick Inc.
and the National Cancer Institute at Frederick.
The work was funded by NIH, NCI, NIST, and the Center
for Cancer Research.
* R. Edgar, M. McKinstry, J. Hwang, A.B. Oppenheim,
R.A. Fekete, G. Giulian, C. Merril, K. Nagashima
and S. Adhya. 2006. High sensitivity bacterial detection
using biotin-tagged phage and quantum-dot nanocomplexes.
Proceedings of the National Academy of Sciences .
Laura Ost, firstname.lastname@example.org , (301) 975-4034