Web Release Date: February 1,
Bioconjugated Gold Nanodots and Nanoparticles for Protein Assays Based on Photoluminescence Quenching
Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 106, Taiwan
Received for review September 22, 2007. Accepted December 10, 2007.
Abstract:
This study describes the first instance of the use of two
differently sized Au nanoparticles (Au NPs), acting separately as donor and acceptor, in homogeneous photoluminescence quenching assays developed for the analysis
of proteins. Introduction of a breast cancer marker
protein, platelet-derived growth factor AA (PDGF AA), to
a solution of 11-mercaptoundecanoic acid-protected, 2.0-nm photoluminescent Au nanodots (LAuND) led to the
preparation of PDGF AA-LAuND as the donor. Thiol-derivative PDGF binding aptamers (Apt) and 13-nm
spherical Au NPs were used to synthesize the Apt-QAuNP
acceptor. The photoluminescence of PDGF AA-LAuND at
520 nm decreased when photoluminescence quenching
occurred between Apt-QAuNP and PDGF AA-LAuND. We
used the PDGF AA-LAuND/Apt-QAuNP-based molecular
light switching system to analyze PDGFs and PDGF
-receptor in separate homogeneous solutions. In the
presence of PDGFs, the interaction between Apt-QAuNP
and PDGF AA-LAuND decreased as a result of competitive
reactions between the PDGFs and Apt-QAuNP. Similarly,
the interaction between Apt-QAuNP and PDGF AA-LAuND
reduced as a result of competitive reactions between
PDGF -receptor and PDGF AA-LAuND. The limits of
detection (LODs) for PDGF AA and PDGF -receptor were
80 pM and 0.25 nM, respectively, resulting from a low
background photoluminescence signal. When using the
Apt-QAuNP as selectors for (a) the enrichment of PDGF
AA and (b) the removal of matrixes possessing intense
background fluorescence from cell media and urine
samples, the LOD for PDGF AA decreased to 10 pM.
Unlike quantum dots, the LAuND provide the advantages
of biocompatibility, ease of bioconjugation, and minimal
toxicity.
Download the full text: PDF | HTML
