Quantitative Detection of Parathyroid Hormone Using Europium Complex Doped Silica Nanoparticles

Parathyroid hormone (PTH) is a hormone that plays a critical role in bone remodeling because it regulates the calcium levels. Either higher or lower than normal range of PTH release can cause serious metabolic disorders such as hyperparathyroidism or hypoparathyroidism. Therefore, the demand of highly sensitive monitoring sensor of PTH is on the rise. However, due to its presence of small size and low concentration in serum, the monitoring of a small change of PTH level is extremely difficult. In this article, we suggested the fabrication of europium complex doped nanoparticles conjugated with PTH antibodies for the sensitive fluorescence monitoring of PTH. For the synthesis of europium complex, 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (NTA) and trioctylphosphine oxide (TOPO) are used to encapsulate europium. The amphiphilic polymer, polyvinylpyrrolidone (PVP), was applied to hydrophobic europium complex, and then silica shell was synthesized on the complex. Using the europium complex doped silica nanoparticles, we could obtain approximately 4.24-fold enhanced fluorescence in low levels of PTH in PBS, when compared to the conventional enzyme-linked immunosorbent assay (ELISA). In addition, we could obtain the sensitive PTH immunoassay in PTH spiked serum with high selectivity.