Detection of prostate-specific antigen utilizing immunomagnetic assay with upconversion nanoparticles
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| Year of publication | 2023 |
| Type | Conference abstract |
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| Description | Prostate cancer is the leading cause of death within the male population worldwide caused by oncologic diseases. The glycoprotein prostate-specific antigen (PSA) produced by the prostate is its most important biomarker. While blood serum concentrations up to 2.5 ng/mL are considered normal and can be generally detected by conventional immunoassays, more sensitive detection schemes are essential for early-stage disease diagnosis. Immunochemical methods, such as the enzyme-linked immunosorbent assay (ELISA), are considered the gold standard for PSA detection. However, there are several limitations that render ELISA insufficient regarding the sensitivity required for early-stage diagnosis.1 Photon-upconversion nanoparticles (UCNPs) are luminescent nanocrystals consisting of an inorganic matrix doped with lanthanide ions. They exhibit anti-Stokes luminescence (the ability to convert low-energy excitation to higher energy emission), thus avoiding optical background interference. When conjugated with biorecognition molecules (e.g., antibodies or streptavidin), UCNPs can be used as a sensitive label in various immunoassay formats, including microtiter plate-based upconversion-linked immunosorbent assay (ULISA).2 Such labels can enhance the assay sensitivity significantly. However, as many biomarkers are extremely low-abundant in body fluids, even ULISA may still not be sensitive enough such that new, even more sensitive assay schemes are needed. Magnetic microparticles (MBs) are a promising alternative solid phase for microtiter plate immunoassays. The superparamagnetic properties of MBs allow for analyte preconcentration and thus improve the assay sensitivity.3 We have developed and optimized a sandwich immunoassay for the detection of PSA based on MBs and UCNP-based labels. We conjugated one type of monoclonal anti-PSA antibody to MBs and the other one to UCNPs via streptavidin-biotin binding, and tested their functionality. Optimal concentrations of MBs and serum were selected, followed by the fully optimized analysis of model real samples of spiked serum. The assay reached an LOD of 11.1 pg/mL, comparable to an ELISA using identical immunoreagents. An additional magnetic preconcentration step further improved the LOD to 0.25 pg/mL, which was 3-fold better compared to the ELISA, and 44-fold better than an MB-based ELISA using identical immunoreagents. These results demonstrate the potential of using MBs combined with UCNPs for the sensitive detection of cancer biomarkers. |
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