Liu Xiong, Dai Qiu, Austin Lauren, Coutts Janelle, Knowles Genevieve, Zou Jianhua, Chen Hui, Huo Qun
Nanoscience Technology Center, Department of Chemistry, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, Florida 32826, USA.
J Am Chem Soc. 2008 Mar 5;130(9):2780-2. doi: 10.1021/ja711298b. Epub 2008 Feb 8.
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.
利用与动态光散射（DLS）测量相结合的金纳米颗粒探针，开发了一种用于检测前列腺癌生物标志物游离前列腺特异性抗原（f-PSA）的一步均相免疫测定法。首先将核心直径约为37nm的球形金纳米颗粒和尺寸为40×10nm的金纳米棒与两种不同的抗PSA一抗偶联，然后用作免疫测定的光学探针。在溶液中存在抗原f-PSA的情况下，纳米颗粒和纳米棒通过形成夹心型抗体-抗原-抗体连接而聚集在一起形成二聚体和寡聚体。通过DLS测量定量监测纳米颗粒-纳米棒二聚体和寡聚体与单个纳米颗粒的相对比例。可以在该相对比例与溶液中抗原量之间建立相关性。纳米颗粒和纳米颗粒寡聚体的光散射强度比蛋白质和其他典型分子高几个数量级，使得能够在低皮摩尔浓度范围内检测纳米颗粒探针。通过这种一步法且无需洗涤的均相免疫测定法检测了浓度范围为0.1至10ng/mL的f-PSA。
