Prostate-specific antigen (PSA) is an intercellular glycoprotein produced primarily by the prostate gland, which is commonly chosen as the initial target for the early diagnosis of prostate cancer. In this work, we demonstrate a simple yet sensitive sandwich-type single-particle enumeration (SPE) immunoassay for the quantitative detection of PSA in a flow chamber. The design is based on the luminescence resonance energy transfer (LRET) between upconversion nanoparticles (UCNPs) and gold nanoparticles (GNPs). The carboxyl group-functionalized UCNPs are conjugated with anti-PSA detection antibodies (Ab1) and serve as the luminescence energy donor, while GNPs are modified with anti-PSA capture antibodies (Ab2) and act as the energy acceptor. In the presence of target antigen (i.e., PSA), the specific immnuoreaction brings the donor and acceptor into close proximity, resulting in quenched luminescence. Through statistical counting of the target-dependent fluorescent particles on the glass slide surface, the quantity of antigens in the solution is accurately determined. The dynamic range for PSA detection in Tris-buffered saline (TBS) is 0-500 pM and the limit-of-detection (LOD) is 1.0 pM, which is much lower than the cutoff level in patients' serum samples. In the serum sample assay, comparable LOD was also achieved (i.e., 2.3 pM). As a consequence, this method will find promising applications for the selective detection of cancer biomarkers in clinical diagnosis.
Analytical chemistry. 2018 Mar 23 [Epub ahead of print]
Xue Li, Lin Wei, Lanlan Pan, Zunyan Yi, Xiao Wang, Zhongju Ye, Lehui Xiao, Hung-Wing Li, Jianfang Wang
State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry , Nankai University , Tianjin 300071 , China., Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research, Ministry of Education, Key Laboratory of Phytochemical R&D of Hunan Province, College of Chemistry and Chemical Engineering , Hunan Normal University , Changsha 410081 , China., Department of Chemistry , Hong Kong Baptist University , Kowloon Tong , Hong Kong, SAR China., Department of Physics , The Chinese University of Hong Kong , Shatin , Hong Kong, SAR China.