Informace o publikaci
Photon-upconversion Nanoparticles for Single-molecule Sensing and Bioimaging
| Autoři | |
|---|---|
| Rok publikování | 2020 |
| Druh | Konferenční abstrakty |
| Fakulta / Pracoviště MU | |
| Citace | |
| Popis | Fluorescence-based detection is a very popular readout method in immunoassays and cell imaging. However, it is limited by autofluorescence and light scattering of the surrounding matrix. This optical background can be elegantly avoided by using photon-upconversion nanoparticles (UCNPs), which emit shorter-wavelength light under near-infrared excitation (anti-Stokes emission). These unique properties enabled us to image single UCNPs by wide-field epiluminescence microscopy and allowed the development of single-molecule (digital) immunoassays. We have synthesized conjugates of polyethylene glycol-coated UCNPs with streptavidin and applied them as a label for the detection of cancer biomarker prostate-specific antigen (PSA). The digital detection based on the counting of individual sandwich immunocomplexes provided a limit of detection (LOD) of 23 fg·ml-1 (800 aM) in 25% human serum, which is 20× more sensitive than the analog readout based on the measurement of output light intensity. The conjugates of UCNPs with streptavidin are also useful as a label in the diagnosis of bacterial diseases. We have developed an immunoassay for the detection of bacterium Melissococcus plutonius, the causative agent of European foulbrood. The assay provided an LOD of 340 CFU·ml-1, and its practical applicability was verified by the analysis of real samples of bees, larvae, and bottom hive debris. Furthermore, the unique optical properties make UCNPs suitable for cell imaging. We have employed PEG-based conjugates for the staining of HER2 biomarker on breast cancer cells. Due to the low optical background, as well as low non-specific binding, the UCNPs provided superior signal-to-background ratio (S/B = 319) compared to the fluorescence-based experiment with the identical immunoreagents (S/B = 6). |
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