Upconversion-linked immunoassays (ULISA) for food and environmental monitoring and single-molecule (digital) diagnostic assays
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| Year of publication | 2022 |
| Type | Conference abstract |
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| Description | We have developed new protocols for the design and surface-modification of upconversion nanoparticles (UCNP) that are excited by near-infrared light and emit visible light (anti-Stokes emission). The UCNPs were used as background-free optical labels in upconversion-linked immunoassays (ULISA) for the sensitive detection of various analytes. Here, I present our recent research on the detection of mycotoxins and micropollutants in food or environmental samples, respectively, as well as the design of digital assays for diagnostic applications. The sensitive detection of mycotoxins such as zearalenone (ZEA) is important to account for increasing food safety standards. We replaced the toxin-conjugate conventionally used in competitive immunoassays by a non-toxic ZEA-mimicking peptide selected from a phage display library as a tracer for a competitive ULISA (LOD: 20 pg/mL). We also developed a direct and an indirect competitive ULISA for the pharmaceutical micropollutant diclofenac (DCF) in river water using DCF-conjugates as tracers (LOD: 20 pg/mL). Digital immunoassays represent a new approach to analyte measurements. Digital assays rely on counting individual immune complexes and provide the potential to achieve a higher assay sensitivity. We have developed digital immunoassays based on UCNPs for detecting blood-based biomarkers: PSA as a marker for prostate cancer (LOD: 23 fg/mL, 800 aM), and troponin as a marker for cardiac diseases (LOD: 10 pg/mL). |
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