Photon-upconversion Nanoparticles as a Background-free Label in Single-Molecule Immunosensing and Bioimaging

The rapid detection of low analyte concentrations is of fundamental importance in many fields, including clinical diagnostics, food control, and environmental screening. Among numerous analytical techniques, immunoassays and immunosensors are gaining attention due to the high specificity provided by antibodies and excellent sensitivity provided by different readout techniques. We have employed immunoanalytical techniques to detect a wide range of analytes, from small molecules, through proteins, to bacteria, utilizing various kinds of transducers and labels. Recently, we are focusing especially on photon-upconversion nanoparticles (UCNPs), which are lanthanide-doped nanocrystals that convert near-infrared light to light of shorter wavelengths. We have exploited UCNPs as a label in upconversion-linked immunoassays for the detection of pharmaceutical diclofenac, mycotoxin zearalenone, and honeybee pathogen Melissococcus plutonius. The low background and high photostability make UCNPs a powerful tool for detecting single molecules. We have developed an optical approach for visualizing individual UCNPs and applied it for the sensitive detection of the cancer biomarker prostate-specific antigen. Finally, the unique optical properties make UCNPs suitable for cell imaging, which was demonstrated by labeling HER2 biomarker on breast cancer cells.

Zdeněk Farka

Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
CEITEC MU, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic