Multiple Fluorescent Labeling of Silica Nanoparticles with Lanthanide Chelates for Highly Sensitive Time-Resolved Immunofluorometric Assays

Abstract

Background: Time-resolved immunofluorometric assays (TrIFA) using lanthanide-labeled nanoparticles have greatly increased the sensitivity of immunoassays. Current labeling strategies, however, use either physical doping of lanthanide chelates into preformed nanoparticles or covalent linking of lanthanide chelates to precursors used for making nanoparticles; both these strategies have drawbacks.

Lateral Flow Immunoassay Using Europium Chelate-Loaded Silica Nanoparticles as Labels

“…Such an observation is expected because the test line captures more labeled anti-HBsAg monoclonal antibodies along with the bound antigens in these samples than in weakly positive and negative samples, reducing the amount of anti-HBsAg monoclonal antibodies that can further migrate to the control line for capture by the goat antimouse IgG immobilized there through "sandwichtype" antigen-antibody interactions. The Eu(III) nanoparticles were basically free from background fluorescence interference owing to their unique fluorescence property (large Stokes shift, long emission wavelength) (13,16,17 ). The concordance between LFIA and ELISA results indicates that fluorescence quenching did not occur in our assay.…”

“…In contrast, with the same pair of monoclonal antibodies, the colloidal gold-based LFIA had a detection limit of 3.51 g/L, which is similar to the previously reported detection limit (1 ). The ELISA method, with the same pair of antibodies used in the LFIA mentioned above, had a detection limit of 0.2 g/L, as described in our previous work (13,15 ). We further investigated the relationship between our LFIA and ELISA.…”

Silica-coated dimers of silver nanospheres as surface-enhanced Raman scattering tags for imaging cancer cells

“…Finally, antibodies were covalently conjugated to the aminated surface by using oxidized dextran 500 as a linker (figure 1d), with which the silica shell and antibodies were coupled through the Schiff reaction (figure 1e). We decided to use oxidized dextran 500 for two reasons: (i) it offers a large number of active groups for antibody conjugation and (ii) it can help increase hydrophilicity of the resultant dimer tags, rendering it more easily dispersible in aqueous solution [34,38]. Figure 2a shows a TEM image of the as-prepared dimer tags with a uniform size and shape.…”

Lanthanide Nanoparticules as Photoluminescent Reporters

“…Covalent linkage of 3-aminopropyl(triethoxy) silane and the chelate on silica nanoparticles in the presence of precisely controlled ratio of Eu(III) and Tb(III) formed luminescent particles, which could be excited by a single wavelength and having two distinctive emission wavelengths [47]. In a similar fashion, the Eu(III) complex with 4,4-bis(1,1,2,2,3,3-heptafluoro-4,6-hexanedion-6-yl)chlorosulfo-o-terphenyl (BHHCT) or Tb(III) chelate with N,N, N 1 ,N 1 -[2,6-bis(3-aminomethyl-1-pyrazolyl)-phenylpyridine] (BPTA) were covalently coupled on aminated silica nanoparticles [48].…”