A gold nanoparticle/latex microsphere-based colorimetric oligonucleotide
detection method
Robert A. Reynolds III, Chad A. Mirkin*, and Robert L. Letsinger
*Department of Chemistry and Center for Nanofabrication
and Molecular Self-Assembly, Northwestern University, 2145 Sheridan
Road, Evanston, Illinois 60208 USA
Abstract: An exceptionally simple and effective DNA detection
methodology based on latex microsphere and gold nanoparticle probes
has been developed. The latex and gold particle probes, which were functionalized
with separate oligonucleotide sequences, undergo hybridization in the
presence of target strands that are complementary to both of the probes.
Duplex formation thus results in linking of gold nanoparticles to the
latex microspheres and a corresponding white-to-red color change, which,
because of the particularly large extinction coefficient of the gold
nanoparticles, is clearly visible to the naked eye. Background signal
caused by unbound gold nanoparticles is significantly reduced by filtering
the solution containing the sample and probes through a size-selective
cellulose acetate membrane. The unbound gold probes move freely through
this membrane while the larger latex particles are trapped. Therefore,
if the latex and gold nanoparticles are joined together via the target
oligonucleotides, the membrane appears red, indicating a positive test
result. If no hybridization takes place, the membrane appears white,
indicating a negative result. The lower detection limits for this system
are 500 pM for a 24 base single-stranded target and 2.5 nM for a duplex
target oligonucleotide.
Back to Contents for access to full
text
Page last modified 5 May 2000.
Copyright ©2000 International Union of Pure and Applied Chemistry.
Questions or comments about IUPAC, please contact, the Secretariat.
Questions regarding the website, please contact web
manager.