title: Aptamer-modified gold nanoparticles for colorimetric determination of platelet-derived growth factors and their receptors.
abstract: We have developed a highly specific sensing system for platelet-derived growth factors (PDGFs) and platelet-derived growth factor receptors (PDGFR) that uses gold nanoparticles (GNPs). We synthesized GNPs modified with an aptamer (Apt-GNPs) that is specific to PDGFs and used them to detect PDGFs by monitoring the changes in the color and extinction of the Apt-GNPs that occur as a result of aggregation. The color of the Apt-GNPs changes from red to purple at low concentrations (<400 nM), but changes only slightly at higher concentrations (>400 nM). We found that the sensitivity of the Apt-GNPs for the three PDGFs is highly salt-dependent, with an optimum condition of 200 mM NaCl. We obtained biphasic curves when plotting of the ratios of the extinction coefficients of the Apt-GNPs at 650 and 530 nm against the concentrations of PDGF-AA at various concentrations of Apt-GNPs. The linear ranges of the increases and decreases in this extinction ratio are 2.5-10 and 10-20 nM, respectively, for 0.42 nM Apt-GNPs and 25-75 and 75-200 nM, respectively, for 8.4 nM Apt-GNPs. When using 8.4 nM Apt-GNPs, the corresponding linear ranges of the increases and decreases in this extinction ratio are 15-100 and 100-400 nM, respectively, for PDGF-AB and 35-150 and 150-400 nM, respectively, for PDGF-BB. In addition, we have developed a homogeneous assay to detect the PDGF receptor-beta (PDGFR-beta) at concentrations as low as 3.2 nM, on the basis of the competition between the Apt-GNPs and PDGFR-beta for PDGF-BB. The results we present in this paper imply that there are practical applications of Apt-GNPs in protein analysis and cancer diagnosis.
authors.affiliation: Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei, Taiwan.
authors.forename: Chih-Ching
authors.initials: CC
authors.lastname: Huang
authors.forename: Yu-Fen
authors.initials: YF
authors.lastname: Huang
authors.forename: Zehui
authors.initials: Z
authors.lastname: Cao
authors.forename: Weihong
authors.initials: W
authors.lastname: Tan
authors.forename: Huan-Tsung
authors.initials: HT
authors.lastname: Chang
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001483:Base Sequence; D003124:Colorimetry / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010982:Platelet-Derived Growth Factor / Q000032:analysis* / Q000737:chemistry; D017479:Receptors, Platelet-Derived Growth Factor / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism
chemical_list: D052157:Aptamers, Nucleotide; D010982:Platelet-Derived Growth Factor; D006046:Gold; D017479:Receptors, Platelet-Derived Growth Factor