title: A one-step homogeneous immunoassay for cancer biomarker detection using gold nanoparticle probes coupled with dynamic light scattering.
abstract: A one-step homogeneous immunoassay for the detection of a prostate cancer biomarker, free-PSA (prostate specific antigen), was developed using gold nanoparticle probes coupled with dynamic light scattering (DLS) measurements. A spherical gold nanoparticle with a core diameter around 37 nm and a gold nanorod with a dimension of 40 by 10 nm were first conjugated with two different primary anti-PSA antibodies and then used as optical probes for the immunoassay. In the presence of antigen f-PSA in solution, the nanoparticles and nanorods aggregate together into pairs and oligomers through the formation of a sandwich type antibody-antigen-antibody linkage. The relative ratio of nanoparticle-nanorod pairs and oligomers versus individual nanoparticles was quantitatively monitored by DLS measurement. A correlation can be established between this relative ratio and the amount of antigen in solution. The light scattering intensity of nanoparticles and nanoparticle oligomers is several orders of magnitude higher than proteins and other typical molecules, making it possible to detect nanoparticle probes in the low picomolar concentration range. f-PSA in the concentration range from 0.1 to 10 ng/mL was detected by this one-step and washing-free homogeneous immunoassay.
authors.affiliation: Nanoscience Technology Center, Department of Chemistry, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, Florida 32826, USA.
authors.forename: Xiong
authors.initials: X
authors.lastname: Liu
authors.forename: Qiu
authors.initials: Q
authors.lastname: Dai
authors.forename: Lauren
authors.initials: L
authors.lastname: Austin
authors.forename: Janelle
authors.initials: J
authors.lastname: Coutts
authors.forename: Genevieve
authors.initials: G
authors.lastname: Knowles
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zou
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Qun
authors.initials: Q
authors.lastname: Huo
mesh_terms: D000906:Antibodies / Q000737:chemistry; D014408:Biomarkers, Tumor / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D007118:Immunoassay; D008027:Light; D053768:Metal Nanoparticles / Q000737:chemistry*; D015335:Molecular Probes / Q000737:chemistry*; D010316:Particle Size; D017430:Prostate-Specific Antigen / Q000032:analysis*; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity
chemical_list: D000906:Antibodies; D014408:Biomarkers, Tumor; D015335:Molecular Probes; D006046:Gold; D017430:Prostate-Specific Antigen