Dipyrrylmetheneboron difluorides as labels in two-photon excited fluorometry. Part I--Immunometric assays.
Seven different two-photon excitable dipyrrylmetheneboron difluoride labels (dipyrrylmethene-BF(2) labels) and a frequently used TAMRA label were conjugated to mouse IgG against alpha-fetoprotein in variable substitution degrees. Altogether 40 IgG conjugates were prepared, and studied with respect to one-photon absorption and emission properties, and two-photon fluorescence efficiency using 1064 nm laser as illumination source. Performance of the IgG conjugates as tracers in a separation-free immunometric assay of alpha-fetoprotein was evaluated using two-photon excitation assay technology, ArcDia TPX. The results show that the dipyrrylmethene-BF(2) labels provide subpicomolar sensitivity, which is an order of magnitude better than that of TAMRA label. The effect of chromophore structure and substitution degree of IgG-label conjugates on the assay performance is discussed.
Laboratory of Biophysics, Institute of Biomedicine, University of Turku, P.O. Box 123, 20521 Turku, Finland. niko.meltola@utu.fi
Niko J
NJ
Meltola
Mika J
MJ
Kettunen
Aleksi E
AE
Soini