Application of europium(III) chelates-bonded silica nanoparticle in time-resolved immunofluorometric detection assay for human thyroid stimulating hormone

Eu(III) chelate-bonded silica nanoparticle was used as a fluorescent label to develop a highly sensitive time-resolved immunofluorometric assay (TrlFA) for human thyroid stimulating hormone (hT:SH). The limit of detection of the assay calculated according to the 2SD method was 0.0007 mlU L-1 and became 0.003 mlU L-1 when serum-based matrix was used for calibrators, indicating that this TrlFA is comparable with the most sensitive assays. The linear range was from 0.005 to 100 mIU L-1 of hTSH with coefficient of variation between 1.9% and 8.3%. The correlation study using 204 blood spot samples from newborns showed that the results from this new method were coincident with that of the commercial dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA) system, with a correlation coefficient of 0.938. The fluorescent nanoparticle label allows directly reading the fluorescent signal, omitting the signal development step required for the DELFIA system, and the whole procedure of this assay is fulfilled within 2 h. Thus, we developed a novel, sensitive, quantitative and simple nanoparticle label-based TrlFA assay, suitable for routine application in hTSH screening of neonatal hypothyroidism. (c) 2012 Elsevier B.V. All rights reserved.