Publication details
Bioconjugates of upconversion nanoparticles for immunochemical detection of tumor biomarkers
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| Year of publication | 2025 |
| Type | Conference abstract |
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| Description | Sensitive detection of clinical biomarkers is crucial for the diagnosis of numerous illnesses. High sensitivity is of the utmost importance especially in the case of tumor diseases, allowing for early-stage cancer diagnosis and monitoring of treatment response. Due to their high specificity conferred by antibodies, immunochemical assays have proven indispensable for biomarker detection. However, conventional immunoassay labels, such as enzymes or fluorophores, often provide insufficient sensitivity for the detection of low-abundance biomarkers. Therefore, various kinds of nanoparticles have been investigated as labels to enhance immunoassay performance. Photon-upconversion nanoparticles (UCNPs) stand out as one of the most promising options. These lanthanide-doped nanocrystals possess the ability to convert near-infrared radiation into light of a shorter wavelength (anti-Stokes emission), significantly reducing the optical background interference. Moreover, their emission spectra can be easily tuned by altering the composition of dopant ions. In the field of immunochemical methods, the heterogeneous assay format is predominant due to its high specificity and sensitivity. However, these desirable properties are ensured by immobilization and washing steps, leading to a prolonged procedure. In contrast, homogeneous immunoassays omit these time-consuming processes, however, at the cost of reduced specificity and sensitivity. To combine the advantages of both the assay formats, we have developed a novel artificial intelligence aided homogeneous immunoassay technique based on massively parallel spectroscopy (MPS). This single-molecule method utilizes two different UCNP antibody labels with distinct emission spectra binding to the analyte molecule, detecting only sandwich immunocomplexes containing the analyte molecule and both labels with distinct emission spectra. The whole mixture is observed by modified upconversion microscopy, where the sandwich immunocomplexes appear as double spots, whose number is assessed by a neural network. We have successfully employed MPS in assays for prostate specific antigen and protein p53, two important cancer biomarkers. Such immunoassay format was utilized for the first time, showing a strong potential to become a fast and high-throughput bioanalytical method. |