Preparation, Characterization, and Time-Resolved Fluorometric Application of Silica-Coated Terbium(III) Fluorescent Nanoparticles

Abstract

Novel silica-coated terbium(III) chelate fluorescent nanoparticles have been prepared and characterized as a new type of fluorescence probe for highly sensitive time-resolved fluorescence bioassay. The preparation was carried out in a water-in-oil microemulsion containing a strongly fluorescent Tb(3+) chelate, N,N,N(1),N(1)-[2,6-bis(3'-aminomethyl-1'-pyrazolyl)-phenylpyridine]tetrakis(acetate)-Tb(3+), Triton X-100, hexanol, and cyclohexane by controlling hydrolysis of tetraethyl orthosilicate. The nanoparticles are spherical and uniform in size, 42 +/- 3 nm in diameter, strongly fluorescent, and highly photostable and have enough of a long fluorescence lifetime (1.52 ms) for time-resolved fluorescence measurement. A stable and nontoxic method was developed for the surface modification and protein immobilization of the nanoparticles. As a model of application, the nanoparticle-labeled streptavidin was prepared and used in a sandwich-type time-resolved fluoroimmunoassay of human prostate-specific antigen (PSA) by using a 96-well microtiter plate as the solid-phase carrier. The method gives a detection limit of 7.0 pg/mL for the PSA assay.

Development of functionalized terbium fluorescent nanoparticles for antibody labeling and time-resolved fluoroimmunoassay application

“…Compared to the previous prepared silica-coated BPTATb 3+ chelate nanoparticles (the fluorescence lifetime and quantum yield are 1.52 ms and 5.3%, respectively) [22], the nanoparticles prepared by the present method have longer fluorescence lifetime and higher fluorescence quantum yield. Since the previous nanoparticles were prepared by the polymerization of TEOS, and the new nanoparticles by the copolymerization of TEOS and AEPS, the different preparation methods would result in the different structures of silica networks in two kinds of nanoparticles, thus the fluorescence quenching effect of the silica network-Tb 3+ chelate interaction in two kinds of nanoparticles would be also different.…”

“…Recently, we developed a method to prepare the BPTA-Tb 3+ chelate-doped silica nanoparticles and established a highly sensitive TR-FIA method by using the Tb 3+ chelate nanoparticle-labeled streptavidin [22], in which the advantages using silica-based lanthanide fluorescent nanoparticles as a fluorescence probe for time-resolved fluorescence bioassay have been discussed. However, the tedious surface activation procedure of the nanoparticles before the biolabeling was needed [22].…”

“…However, the tedious surface activation procedure of the nanoparticles before the biolabeling was needed [22]. In the present work, the preparation method of BPTA-Tb 3+ chelate-doped silica nanoparticles was further improved by using a copolymerization method between TEOS and AEPS in a water-in-oil microemulsion consisting of BPTA-Tb 3+ chelate, Triton X-100, octanol, cyclohexane, water, and ammonia water.…”

“…The new nanoparticles are spherical and uniform in size, strongly fluorescent having larger fluorescence quantum yield and a long fluorescence lifetime. Since amino groups have been directly introduced to the nanoparticle's surface by the copolymerization method, the nanoparticles are directly available for biolabeling without tedious surface activation procedure [7,22,23]. By using the nanoparticle-labeled anti-human AFP antibody, a simple TR-FIA method for determination of AFP in human serum samples was established to evaluate the utility of the fluorescent nanoparticles as a new type of fluorescence probe.…”

Demonstration of true‐color high‐contrast microorganism imaging for terbium bioprobes

“…The UV optics match the peak absorption (300-330 nm) for the most biocompatible terbium complexes (9,18,21). A 0.5-mW, 315 nm LED source (UVTOP310 with a hemispherical lens window, Sensor Electronic Technology, Columbia, SC, USA, http://www.s-et.com) replaced the previously reported highpower, 365 nm (UV) LED (1,31); since the typical objective lens and cover slip glass cut-off transmission is below 330 nm, a MicroSpot Focusing UV objective 403, 240-360 nm, and NA 5 0.50 (Thorlabs, LMU-40X-UVB, http://www.thorlabs.…”