Abstract
Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted considerable attention in detection of biological analytes and bioimaging owing to their superior optical properties, including high photochemical stability, sharp emission bandwidth, large anti-Stokes shifts, and low toxicity. In this work, we fabricated UCNP-linked immunosorbent assay (ULISA) for the sensitive detection of carbohydrate antigen 19-9 (CA19-9). The design is based on amino-functionalized SiO2-coated Gd-doped NaYF4:Yb3+,Er3+ upconversion nanoparticles (UCNPs@SiO2-NH2) as a direct background-free luminescent reporter; a secondary anti-IgG antibody (Ab2) was conjugated to the surface of UCNPs@SiO2-NH2 (UCNP-Ab2), and UCNP-Ab2 was used for specific targeting of CA19-9. The UCNPs were well characterized by TEM, SEM, XRD, FT-IR, and UV-vis. The detection process was similar to enzyme-linked immunosorbent assay (ELISA). UCNPs were used as signal transducer to replace the color compounds for an enzyme-mediated signal amplification step. An anti-CA19-9 primary antibody (Ab1) was fixed for capturing the CA19-9, and the fluorescence signal was obtained from the specific immunoreaction between UCNP-Ab2 and CA19-9. Under optimum conditions, this ULISA shows sensitive detection of CA19-9 with a dynamic range of 5–2,000 U/ml. The ULISA system shows higher detection sensitivity and wider detection range compared with the traditional ELISA for CA19-9 detection. This strategy using UCNPs as signal transducer may pave a new avenue for the exploration of rare doped UCNPs in ELISA assay for clinical applications in the future.
Highlights
Cancer has been the leading cause of global death
The as-prepared upconversion nanoparticles (UCNPs) with oleic acid as a stabilizer were coated with silica shell, which enhance the dispersion of UCNPs and provide a large number of sites for subsequent functional modification
In the presence of carbohydrate antigen 19-9 (CA19-9), the detection signal was obtained by the specific immunoreaction between UCNPs-Ab2
Summary
Cancer has been the leading cause of global death. Among various types of cancers, pancreatic cancer with extremely high mortality and poor prognosis is ranked the 4th leading cause of cancer death in the USA (Wolfgang et al, 2013; Siegel et al, 2019). There are some limitations that hamper its routine application in the clinical detection of cancer biomarkers due to the ELISA tests being mainly based on the spectroscopic detection of a chromogenic substrate that yields a measurable color product during the assay This colorimetric signal readout significantly affects the accurate detection of the target biomolecules as the color intensity is proportional to the concentration of target analytes. This ULISA could achieve sensitive and rapid detection of CA19-9 This design strategy of using UCNPs as the signal transducer to provide fluorescence as an alternative output to color intensity will be extended to wide-range applications in the area of immunodetection and disease diagnosis. The upconversion luminescence signals were recorded under a custom-built upconversion microplate reader equipped with a 980-nm laser transmitter
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
